[Index]
Monthly Global Tropical Cyclone Summary September 2000
[Summaries and Track Data] [Prepared by Gary Padgett]
| Tropical
Cyclones
[Index] |
Monthly Global Tropical Cyclone Summary September 2000 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
SEPTEMBER, 2000
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
***********************************************************************
SOUTHERN HEMISPHERE TROPICAL CYCLONE NAMES
2000 - 2001 SEASON
TROPICAL CYCLONE NAMES for the AUSTRALIAN REGION
The Australian Bureau of Meteorology maintains three Tropical
Cyclone Warning Centres (TCWC): Perth, Western Australia; Darwin,
Northern Territory; and Brisbane, Queensland. Each centre is allotted
a separate list of tropical cyclone names for tropical cyclones forming
within its area of responsibility (AOR). In addition a TCWC located at
Port Moresby, Papua New Guinea (PNG)--a former Australian territory--
maintains a list of native names to assign to the very rare tropical
cyclones which form within its AOR.
The AORs of the respective centres are:
(1) Perth - 125E westward to 90E. Technically, Perth's AOR is south of
10S with Indonesia being responsible for waters north of 10S, but
I believe the plan is that any rare tropical cyclone which might
form north of 10S would be named by Perth.
(2) Darwin - 125E eastward to 138E and extending northward to the
equator. There is a little irregularity with the eastern border
in the Gulf of Carpentaria. The Darwin TCWC issues High Seas
Warnings for the entire Gulf of Carpentaria, but Brisbane issues
Tropical Cyclone Advices and names cyclones in the eastern portion
of the Gulf.
(3) Brisbane - 138E eastward to 160E and generally south of 10S. The
northern border with the Port Moresby AOR is somewhat irregular.
(4) Port Moresby, PNG - immediate vicinity of the island of New Guinea
and eastward to 160E generally north of 10S although the southern
border is somewhat irregular.
Names for the 2000-2001 season (** indicates name has already been
assigned):
Perth Darwin Brisbane Port Moresby
-----------------------------------------------------------------------
Sam ** Winsome Wylva Epi
Terri ** Alistair Abigail Guba
Vincent Bonnie Bernie Ila
Walter Craig Claudia Kama
Alex Debbie Des Matere
Bessi Evan Erica Rowe
Chris Fay Fritz Tako
Dianne George Grace Upia
Errol Harvey
Fiona Ingrid
Graham Jim
Harriet Kate
Inigo Larry
Jana Monica
Ken Nelson
TROPICAL CYCLONE NAMES for the SOUTHWEST INDIAN OCEAN
and the SOUTH PACIFIC OCEAN
The Tropical Cyclone Warning Centre (TCWC) at Nadi, Fiji, has
tropical cyclone warning responsibility for the South Pacific east of
160E and from the equator to 25S. The Meteorological Service of New
Zealand at Wellington has warning responsibility for waters south of
25S, but almost all tropical cyclones in this basin form north of 25S.
When a rare cyclone forms in the Wellington area of responsibility
(AOR), it usually will be assigned a name from the Fiji list (such as
was done for Tropical Cyclone Gita in February, 1999.)
Tropical cyclone warning responsibility for South Indian waters west
of 90E are shared by several TCWCs. The Regional Specialty
Meteorological Centre (RSMC) for the region is the office of Meteo
France on the island of La Reunion. However, following a long-standing
practice, the sub-regional centres at Mauritius and Madagascar share
the responsibility for actually naming tropical storms with Mauritius
naming systems east of 55E and Madagascar covering the area west of
55E. RSMC La Reunion issues warnings for the basin independently of
these sub-regional centres, but only advises regarding when or when not
to assign a name to a developing cyclone. (I included the Southwest
Indian names in the August summary but am repeating them here for
completeness.)
Names for the 2000-2001 season (** indicates name has already been
assigned):
Southwest Indian South Pacific
-----------------------------------------------------------------------
Ando ** Nancy Oma Beni
Bindu ** Oda Paula Cilla
Charly ** Premnath Rita Dovi
Dera Quirin Sose Eseta
Evariste Rakoto Trina Fili
Francois Suzy Vicky Gina
Gaby Tovo Waka Heta
Hans Ursula Yolande Ivy
Idriss Vimla Zoe Judy
Jakoba Wenda Ami Kerry
Kiran Xino
Lanto Yul
Mathieu Zoe
*************************************************************************
SEPTEMBER HIGHLIGHTS
--> Atlantic basin very active with seven named storms
--> Active Northwest Pacific basin features two super typhoons
***********************************************************************
***** Topic of the Month for September *****
SEASONAL STATISTICS FOR THE CENTRAL NORTH PACIFIC
For the Topic of the Month feature in the July summary I presented
some seasonal statistics for the Eastern North Pacific compiled by
John Wallace of San Antonio, Texas. This month I am including a
similar table for the Central North Pacific--that region of the North
Pacific lying between longitudes 180 and 140W. I prefer to consider
the entire North Pacific east of the Dateline as one basin (Northeast
Pacific), but due to the fact that warnings are handled by two
different agencies (TPC/NHC in Miami and CPHC in Honolulu), the areas
east and west of 140W are often considered separately.
A full description of the seven parameters in the table below would
needlessly lengthen this article. Definitions can be found on the
Colorado State University Tropical Meteorology site:
http://typhoon.atmos.colostate.edu/forecasts/2000/august2000/
definitions.html>
I will, however, simply explain the abbreviations:
NS: Named Storms (includes unnamed storms added in post-analysis)
H: Hurricanes
IH: Intense Hurricanes
NSD: Named Storm Days
HD: Hurricane Days
IHD: Intense Hurricane Days
NTC: Net Tropical Cyclone Activity (%)
The statistics given in the following table are based upon all
tropical cyclones of tropical storm intensity or higher which either
formed in or moved through the Central North Pacific. The various
"days" parameters include only the period in which the cyclone was
located between longitudes 180 and 140W. Three storms which formed
west of the Dateline and moved eastward into the Central North Pacific
are not included due to their omission from the Northeast Pacific
Best Track file. These storms are: Virginia (1968), Carmen (1980),
and Skip (1985). The latter two actually formed as tropical
depressions in the Central Pacific, moved westward across the Dateline
and were named by JTWC, then recurved eastward and existed briefly
as tropical cyclones east of longitude 180. However, for Hurricane
John of 1994, the time spent east of the Dateline after it had recurved
and moved northeastward is included in the NSD and HD parameters.
Central North Pacific Seasonal Parameters
1966 - 1999
YEAR NS H IH NSD HD IHD NTC
1966 3 1 0 8.75 2.25 .00 54
1967 3 1 0 11.00 .50 .00 51
1968 0 0 0 .00 .00 .00 0
1969 0 0 0 .00 .00 .00 0
1970 2 1 0 5.50 .50 .00 36
1971 2 1 0 3.25 1.75 .00 37
1972 5 1 1 20.75 9.00 1.75 170
1973 2 1 1 10.50 4.50 .25 92
1974 2 1 1 4.50 3.50 .25 77
1975 1 1 0 3.00 .75 .00 26
1976 1 1 0 8.75 4.75 .00 53
1977 0 0 0 .00 .00 .00 0
1978 6 4 2 30.00 16.25 2.75 301
1979 0 0 0 .00 .00 .00 0
1980 1 1 0 4.50 2.75 .00 37
1981 2 0 0 3.00 .00 .00 17
1982 10 5 1 30.25 6.50 1.50 252
1983 4 1 1 12.00 1.50 1.25 110
1984 4 1 1 10.25 2.75 .25 96
1985 5 4 2 18.25 12.75 2.75 260
1986 2 2 1 6.50 4.25 1.50 116
1987 4 1 0 12.50 4.25 .00 75
1988 4 2 2 14.25 10.75 4.25 238
1989 1 1 0 4.50 2.50 .00 36
1990 3 1 1 10.75 2.75 2.25 123
1991 2 2 0 4.50 1.50 .00 50
1992 7 2 2 16.25 8.50 2.50 223
1993 3 2 1 13.25 8.50 1.50 151
1994 8 5 3 34.00 18.50 12.75 527
1995 0 0 0 .00 .00 .00 0
1996 0 0 0 .00 .00 .00 0
1997 4 0 0 11.50 .00 .00 44
1998 1 1 0 2.00 .25 .00 22
1999 2 2 1 9.00 7.25 .25 112
Avg. 2.8 1.4 0.6 9.5 4.1 1.1 100
In terms of NTC the year 1994 stands head-and-shoulders above all
other years. It is not the year with the highest number of named
storms and ties 1982 for the highest number of hurricanes, but in
terms of HD and IHD it ranks far above all other years. All three
of the intense hurricanes that prowled the waters of the Central
Pacific that summer were Category 5 hurricanes on the Saffir/Simpson
scale--Emilia, Gilma, and John. Hurricane John lasted 31 days and
holds the record as the world's longest-lived tropical cyclone. John
is also the only tropical cyclone on record to travel from the Eastern
North Pacific across the Central North Pacific and enter the Western
North Pacific, and then move back eastward and re-enter the Central
North Pacific.
A majority of the tropical cyclones in the Central North Pacific
are visitors from east of 140W. Of the 98 tropical storms or
hurricanes in the region from 1966-2000 (there were four Central
Pacific storms in 2000), 32 actually formed between 140W and the
Dateline. Those storms are listed below (an asterisk following the
name indicates that the cyclone moved across longitude 180 into the
Northwest Pacific basin):
1967 - Sarah * 1985 - Nele
1970 - Dot 1987 - Oka, Peke *
1972 - June, Ruby * 1988 - Uleki *, Wila
1974 - Olive 1990 - Aka *
1975 - unnamed 1992 - Ekeka *, Hali, Iniki
1976 - Kate 1993 - Keoni *
1978 - Susan 1994 - Li *, Mele, Nona
1982 - Akoni, Ema, Hana, Iwa 1997 - Oliwa *, Paka *
1984 - Keli, Lala, Moke 2000 - Upana ++, Wene &&
++ - Upana weakened and warnings were dropped by CPHC, but the remnant
LOW moved into the NWP basin, redeveloped, and was named Chanchu
by JMA
&& - Wene actually formed as a tropical depression just west of the
Dateline, moved northeastward, and reached tropical storm
intensity near 179W
***********************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for September: 1 tropical depression
2 tropical storms
5 hurricanes
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory. All
references to sustained winds imply a 1-min averaging period unless
otherwise noted.
Atlantic Tropical Activity for September
----------------------------------------
After getting off to a slow start, the month of September became
very active in the latter half. Seven named tropical cyclones formed,
plus one short-lived tropical depression. The only other two years
on record in which seven storms formed in September are 1949 and 1988.
Also, five of the cyclones reached hurricane intensity--above normal,
but not all that uncommon--five hurricanes formed in September, 1998.
Two storms, Gordon and Helene, made landfall along the Gulf Coast of
the U. S. as tropical storms. Hurricane Keith formed at the end of
the month in the northwestern Caribbean and quickly intensified into
a Category 4 hurricane on the Saffir/Simpson scale just off the coast
of the southern Yucatan Peninsula. After stalling just offshore, the
hurricane weakened and made landfall near the Belize/Mexico border as
a strong tropical storm. Keith later re-intensified in the Bay of
Campeche and made a final landfall in eastern Mexico north of Tampico
as a strong Category 1 hurricane. Hurricanes Florence, Isaac, and
Joyce as well as weak Tropical Storm Ernesto all remained at sea.
A short-lived and generally weak tropical depression formed in the
northwestern Gulf of Mexico on 8 September and moved inland the next
day near the mouth of the Sabine River which forms the boundary between
Louisiana and Texas. The depression was spawned by the interaction
between a low-level trough which had persisted over the Gulf and a
convective cluster associated with a tropical wave. Squalls with gusts
to tropical storm force occurred well to the east of the center at some
buoys and a C-MAN station near Southwest Pass. More information on
this system can be found in the official report authored by Jack Beven
on TPC/NHC's website: http://www.nhc.noaa.gov/2000nine.html> .
The official TPC/NHC tropical cyclone reports prepared by the
Hurricane Specialists are now available for most of the 2000 Atlantic
basin tropical cyclones. The reports are very interesting and
informative, and links to them can be found at the following URL:
http://www.nhc.noaa.gov/2000.html> . Since I am running so far
behind schedule, and since I think it highly likely that just about
every person who reads these summaries has access to the internet, I
am going to trim down the amount of material I write about the
remaining Atlantic cyclones--primarily including a few items of
interest which are not mentioned in the official NHC reports.
Tropical Storm Ernesto (TC-08)
2 - 3 September
-------------------------------
The first mention of the tropical wave which ultimately developed
into Tropical Storm Ernesto was in a Tropical Weather Outlook issued
by TPC/NHC early on 29 August. A tropical wave was passing south of
the Cape Verde Islands. Whether or not this was the same wave which
moved off the coast of Africa on 27 August or a second wave on its
heels isn't completely clear. A 1010-mb LOW was noted on the wave
axis at 1800 UTC, and the Tropical Weather Outlook at 2230 UTC on the
30th indicated that convection had become better organized. At the
time upper-level winds in the region a few hundred miles west of the
Cape Verdes were favorable for continued development, but became less
favorable later as the system moved farther to the west. The wave
was given a poor chance for development on 31 August due to hostile
winds aloft, but at 0900 UTC on 1 September a Special Tropical
Disturbance Statement was issued which indicated that strong thunder-
storms had developed overnight near the center of circulation and that
a depression could possibly form during the day if the convection
persisted near the LLCC. However, the system was moving west-
northwestward at 17-22 kts and this rapid translational speed was
judged to be an inhibiting factor for significant strengthening.
The system remained well-organized and by the afternoon of the 1st
it appeared that a depression might be forming. Advisories were
initiated on TD-08 at 0300 UTC on 2 September with the poorly-defined
center estimated to be about 750 nm east of the island of Martinique.
The depression was moving slightly north of due west at about 12 kts.
Deep convection increased significantly overnight near the LLCC and
TAFB assigned a Dvorak rating of T2.5 at 0600 UTC. This, in
conjunction with some 30-kt wind reports from a buoy well north of
the center, was the basis for upgrading the depression to Tropical
Storm Ernesto at 0900 UTC. Outflow had improved somewhat to the
north, but the cyclone was still experiencing the effects of southerly
shear.
Ernesto never intensified beyond minimal tropical storm intensity.
The hostile upper-level environment over the eastern Caribbean which
had sheared Chris and Debby persisted for two or three weeks and
Ernesto became its next victim. Such a highly unfavorable pattern
during the peak of the hurricane season is rather unusual, especially
in a year which was overall quite active. Had this feature not been
present, and Chris, Debby and Ernesto been allowed to have developed
into well-organized hurricanes, things could have been very different
for the U. S. East Coast. Satellite images around 0000 UTC on the 3rd
revealed that the LLCC was located on the edge of the deep convection
but close enough to justify keeping Ernesto as a tropical storm. In
addition a QuikScat pass at 02/2200 UTC showed several places with
tropical storm-force winds to the north of the center.
The weak tropical storm continued to move to the west-northwest
at about 15 kts on 3 September, and the large upper-tropospheric trough
situated about 15 degrees to the west continued to create strong south-
southwesterly shear over the cyclone. During the afternoon the cloud
pattern began to deteriorate rapidly and low-level cloud motions
indicated that a closed circulation no longer existed, so Ernesto was
downgraded to a tropical wave at 2100 UTC. The final advisory position
was roughly 300 nm northeast of Guadeloupe. Interestingly, as was the
case with Debby, some of the numerical models had forecast that Ernesto
would strengthen in spite of the shearing environment. And again, as
with Debby, this failed to materialize.
NOTE: The official report on Tropical Storm Ernesto, authored by
Miles Lawrence, is now available on TPC/NHC's website at the following
URL: http://www.nhc.noaa.gov/2000ernesto.html> .
Hurricane Florence (TC-10)
11 - 18 September
---------------------------
Hurricane Florence was a Category 1 hurricane on the Saffir/Simpson
scale which formed in the subtropics and later brushed the island of
Bermuda as it accelerated to the northeast. The official storm report
on Florence, prepared by James Franklin, can be found at the following
URL: http://www.nhc.noaa.gov/2000florence.html>. I recommend that
interested readers first connect to TPC/NHC's website and read James'
report, which contains a tabular listing and plot of the analyzed
"best track" as well as plots of meteorological information.
Florence serves as a good illustration of the revisions to the
operational track and (especially) intensities that are often made
during the post-storm analysis process. The "best track" indicates
that Florence had reached tropical storm intensity by 1200 UTC on
11 September--this based on a QuikScat pass. The 1030 UTC Tropical
Weather Outlook still referred to the system as a non-tropical LOW but
indicated that convection was becoming better organized and that there
was a potential for tropical cyclone development over the next few
days. The first advisory on the LOW was issued at 11/1500 UTC,
classifying the system as Tropical Depression Ten. The discussion
bulletin mentioned the earlier QuikScat pass and indicated that a
reconnaissance aircraft was on the way to investigate the system.
A special advisory was issued at 1800 UTC, upgrading Florence to
a 50-kt tropical storm. This was based on a reconnaissance report of
winds to 64 kts at 300 m in convection southeast of the center. While
the "best track" indicates that Florence reached hurricane intensity
for a brief period at 1800 UTC, it should be pointed out that in real-
time the storm was not upgraded to a hurricane until 2100 UTC on the
12th. The discussion bulletin issued along with the 11/2100 UTC
advisory contains a good example of the sort of decisions the
forecaster often has to make on the spot, some of which (as in this
case) are later revised after a thorough analysis of all the data.
I quote from Discussion Number 3 (5 PM EDT Mon, Sep 11 2000), written
in fact by James Franklin: "We are reminded once again that there is no
substitute for aircraft reconnaissance observations. While the Dvorak
satellite technique estimated an intensity of 35 kts, the recon found a
large area of winds at the 1000 ft level in excess of 60 kts, and even
a small area of winds in excess of 75 kts on the edge of the
convection. This supports surface winds of 60 to 65 kts. I would like
to see these winds persist a bit before making Florence a hurricane."
Since the convection soon began to wane, the decision was made not
to upgrade Florence to a hurricane at the time, but in post-analysis it
was apparently felt that the observations from the reconnaissance plane
justified upgrading the storm to minimal hurricane status for a 12-hour
period. Eric Blake, who wrote a summary for me of Hurricane Alberto,
researched the "best track" database and concluded that Alberto was the
first known Atlantic hurricane to have reached hurricane intensity
three separate times during its history. Remarkably, the same thing
happened again just a month later with Hurricane Florence.
Florence later passed only 65 nm to the northwest of Bermuda but had
no significant effects on the island. There were three drownings along
the coast of North Carolina due to rip currents likely related to the
storm. In its later stages Florence was headed for the Cape Race,
Newfoundland, area but was absorbed by a large extratropical LOW while
still to the south of the island. The peak intensity of 70 kts was
reached on 16 September when Florence was located about 275 nm north-
east of Bermuda.
Hurricane Gordon (TC-11)
14 - 19 September
-------------------------
Hurricane Gordon was a Category 1 hurricane on the Saffir/Simpson
scale which formed in the northwestern Caribbean Sea near the Yucatan
Peninsula, reached hurricane intensity in the southeastern Gulf of
Mexico, and later weakened to a tropical storm before making landfall
in the Big Bend area of northwestern Florida. The official storm
report on Gordon, prepared by Stacy Stewart, can be found at the
following URL: http://www.nhc.noaa.gov/2000gordon.html>. I recommend
that interested readers first connect to TPC/NHC's website and read
Stacy's report, which contains a tabular listing and plot of the
analyzed "best track" as well as plots of meteorological information.
As the official report points out, Gordon developed from a tropical
wave which left the coast of western Africa on 4 September and traveled
across the Atlantic and Caribbean. This wave was somewhat interesting
in its pre-depression stage in the northwestern Caribbean in that for
a couple of days its appearance in satellite imagery was suggestive of
a tropical depression, but reconnaissance flights on both 12 and 13
September could find no evidence of a low-level circulation, although
a well-defined mid-level circulation was quite apparent. Finally on
the 14th a reconnaissance plane was able to find a small circulation
just off the Yucatan coast, so advisories were initiated on Tropical
Depression Eleven at 1500 UTC.
Immediately after being upgraded to a depression, the system moved
inland over the Yucatan Peninsula. During the morning of 15 September
the low-level center reached the north-central coast of Yucatan while
the mid-level center and deeper convection were farther to the east.
Richard Henning, a meteorologist at Eglin AFB and a member of the
53rd Weather Reconnaissance Squadron, The Hurricane Hunters, was
present on a flight into the depression on the evening of the 15th.
Rich related to me that the low-level center, which had for much of
the day been "wandering along the beach" to the west of the mid-level
center, suddenly seemed to be "sucked into" the deeper convection to
the east or northeast. That flight found 59-kt winds at 450 m just
east of the center, leading to Tropical Storm Gordon's being named at
2100 UTC.
Based on a ship report Gordon was upgraded to a hurricane in a
special update issued at 2145 UTC on the 16th. The storm reached its
estimated peak intensity of 70 kts around 0600 UTC on 17 September.
Operationally, the highest MSW assigned to Gordon was 65 kts, the
slight increase of 5 kts being decided upon during post-storm analysis.
There was another interesting aspect of Gordon which should be pointed
out. The peak flight-level wind found by a reconnaissance aircraft
was 89 kts at 0544 UTC on 17 September. The accompanying minimum
CP found at that time was 992 mb. A little over two hours later, at
0805 UTC, the pressure had fallen 11 mb to 981 mb--the minimum for the
storm--but the maximum flight-level wind found during that pass was
only 80 kts.
Gordon weakened to a 55-kt tropical storm before making landfall
due to the combined effects of southwesterly shearing and entrainment
of drier air into the circulation. The center of the cyclone made
landfall just northwest of Cedar Key, Florida, near the mouth of the
somewhat-famous Suwanee River. Damage from the storm was relatively
light--mainly downed trees and power lines. Some homes along the
Florida west coast between Tampa Bay and Cedar Key had minor roof
damage and some coastal roads were flooded. The damage estimate for
the U. S. is $10.8 million. One death occurred when a surfer
drowned in heavy seas near Pensacola, Florida, as Gordon was making
landfall farther to the east.
There were 23 deaths reported in Guatemala due to flooding from
heavy rains in mountainous areas which may have been due in part to
the depression and pre-depression stages of Gordon in the northwestern
Caribbean and over Mexico's Yucatan Peninsula.
Tropical Storm Helene (TC-12)
15 - 25 September
------------------------------
Tropical Storm Helene was a fairly long-lived and much-traveled
tropical cyclone which reached tropical storm intensity twice and
made landfall along the Florida Panhandle coast near Fort Walton
Beach. The official storm report on Helene, co-authored by Eric
Blake and Lixion Avila, can be found at the following URL:
http://www.nhc.noaa.gov/2000helene.html>. The author recommends that
interested readers first connect to TPC/NHC's website and read Eric's
and Lixion's report, which contains a tabular listing and plot of the
analyzed "best track" as well as plots of meteorological information.
Like Florence, Helene serves as a good illustration of the revisions
that may be made in the "best track" as compared with the real-time
operational warnings. The most notable change was the reclassification
of the system as a tropical storm after it emerged back into the North
Atlantic off the Virginia coast on 24 September. No operational
advisories were issued for this portion of Helene's life--the storm
being carried operationally as a non-tropical system. The global
tropical cyclone tracks file for September, which I disseminated in
late October, indicated that Helene had subtropical characteristics
during this phase of its history. This was based on the opinion of
David Roth, a meteorologist at HPC who has extensively studied hybrid
and subtropical systems. During post-storm analysis it was decided
to treat the system as a tropical storm even though its appearance was
not exactly that of a classic tropical cyclone. Reports from a ship,
the Neptune Olivine, were extremely helpful in determining the
intensity of Helene during its North Atlantic phase. The analyzed
"best track" reports a peak MSW of 60 kts at 25/0600 UTC--the same
as the peak intensity attained by Helene while in the Gulf of Mexico.
Helene developed from a tropical wave which left the African coast
around 10 September. The system was upgraded to Tropical Depression
Twelve on 15 September about 500 nm east of the island of Guadeloupe.
However, the next day the system appeared to be weakening and a
reconnaissance flight discovered that there was no longer a closed
low-level circulation, even though winds to 55 kts at 450 m were found
north and east of the wave. The residual wave continued to move west-
ward through the Caribbean Sea, and on the afternoon of the 19th a
NOAA plane found that the depression had regenerated in the north-
western Caribbean near Grand Cayman and was moving west-northwestward.
All conditions seemed to be on "go" for continued intensification of
the regenerated TD-12, but the system remained very weak with minimal
convection through the 20th. It is possible that an area of convection
in the southwestern Gulf of Mexico, which on 19 September seemed to
be rapidly organizing, may have helped to inhibit the depression from
strengthening further at the time. By the 20th the outflow from
Tropical Storm Norman in the Pacific was streaming across the Bay of
Campeche and the disturbance in that area weakened.
TD-12 moved into the southeastern Gulf of Mexico late on the 20th,
and by the early morning of 21 September the satellite signature had
improved with deep convection forming near the center and enhanced
outflow evident. Buoy reports indicated that the cyclone was
strengthening, and during the morning a reconnaissance flight found
winds of 58 kts at 450 m. An update was issued at 1300 UTC upgrading
the depression to Tropical Storm Helene, and the first regular advisory
was issued at 1500 UTC. The highest MSW reported operationally for
Helene was 55 kts, but in post-analysis this was increased to 60 kts at
1800 and 22/0000 UTC. Increased shear caused the storm to later weaken
and also caused most of the associated active weather to be displaced
well to the east of the center. The center of Helene made landfall
about 7:00 AM locally (1200 UTC) near Fort Walton Beach, Florida, with
winds of only 35 kts and quickly weakened into a depression.
The author spent the night of the 21st in Fort Walton Beach at the
home of a friend and co-worker. We had dinner in a restaurant over-
looking the beach and then walked out to the end of a fishing pier
which extends about 300 ft (~100 m) into the Gulf. We estimated that
the waves breaking on the beach were about 3 ft (1 m) in height. At
one point during the wee hours of the morning I woke up and looked
out the door to see the rain coming down nearly horizontally, but the
next morning there were only a few small twigs and pine needles on my
car. At around 7:00 AM--the time of landfall--I walked outside and
the wind was completely calm.
The only fatality reported in association with Tropical Storm Helene
was a man killed in an F2 tornado in South Carolina as the tropical
depression moved through the region on 23 September. Near Tallahassee,
Florida, the storm dumped almost 230 mm of rain, causing extensive
flooding, but no damage figures are available.
Hurricane Isaac (TC-13)
21 September - 2 October
------------------------
Hurricane Isaac was a classically-forming Cape Verde hurricane which
followed a rather smooth parabolic track over the eastern and central
Atlantic. The storm attained Category 4 status on the Saffir/Simpson
scale as its winds climbed to an estimated peak of 120 kts--tying Isaac
with Hurricane Keith as the most intense hurricanes of the season. The
official storm report on Isaac, prepared by Richard Pasch, can be found
at the following URL: http://www.nhc.noaa.gov/2000isaac.html>. I
recommend that interested readers first connect to TPC/NHC's website
and read Richard's report, which contains a tabular listing and plot of
the analyzed "best track" as well as plots of meteorological
information.
Since my purpose here is to complement the storm report already
available on NHC's website, and since Isaac remained far from any
populated shores, there is not a whole lot to write. A few slight
modifications to the operational MSW values were made in the "best
track". Operationally, Isaac was not upgraded to a hurricane until
23/1800 UTC, but the "best track" shows it reaching hurricane intensity
six hours earlier. Between its two periods of Category 3 intensity,
when the hurricane underwent some shearing, the operational MSW did
not drop any lower than 80 kts, but in the post-storm review the MSW
was decreased to 75 kts for a twelve-hour period on 26 September.
Isaac's initial intensification to Category 3 status in the far
eastern Atlantic on 24 September was quite unusual, especially
considering that its winds climbed to 105 kts over SSTs less than
27 C. Another very interesting aspect of the storm becomes evident
when perusing a tracking map of all the Atlantic tropical cyclones for
the season. Hurricane Isaac's track was amazingly close to the track
of earlier Hurricane Alberto. Both cyclones began in almost the
same location, and the two tracks veritably lie on top of each other
in several spots. Isaac passed about 200 nm farther east of Bermuda
than did Alberto, but the storm's tracks cross again near 50W. At
this point Alberto's track begins the huge week-long clockwise loop
whereas Isaac's continues on a straight shot toward the British Isles.
Although Isaac remained far from U. S. shores, passing about 450 nm
east of Bermuda, swells generated by the large, powerful hurricane
were responsible for the capsizing of a boat off Long Island. One man
on board the boat reportedly drowned before he could be rescued.
Hurricane Joyce (TC-14)
25 September - 2 October
------------------------
Joyce was another Cape Verde hurricane which formed on the heels of
Isaac. However, in stark contrast to the earlier hurricane, which
recurved and intensified into a Category 4 storm on the Saffir/Simpson
scale, Joyce followed a slightly oscillating westward track at low
latitudes--always remaining south of 13N--and peaked at only 80 kts.
The official storm report on Joyce, prepared by Miles Lawrence, can be
found at the following URL: http://www.nhc.noaa.gov/2000joyce.html>.
I recommend that interested readers first connect to TPC/NHC's website
and read Miles' report, which contains a tabular listing and plot of
the analyzed "best track" as well as plots of meteorological
information.
After Joyce had formed in the eastern Atlantic on 26 September not
all that far away from Hurricane Isaac--at 26/1200 UTC Joyce was only
about 700 nm southeast of the hurricane--it seemed logical to think
that the new storm would follow a track similar to Isaac's. However,
a mid-level ridge which had built in behind the earlier storm kept
Joyce moving on a westward track throughout its entire life.
Probably the biggest question which has been raised regarding Joyce
is: What caused the storm to dissipate in an environment where shear
was not particularly great and there were plenty of warm SSTs? There
seems to be a fairly good consensus of opinion that dry air entrainment
was the major factor in Joyce's weakening when other factors seemed
to be favorable for a major hurricane to approach the Lesser Antilles.
Roger Edson argues that a lack of southwesterlies to the south of the
cyclone, and hence a lack of tropical moisture from the equatorial
region, was the major reason for the drier-than-normal environment
surrounding Joyce.
Hurricane Joyce was very similar in many regards to Hurricane Cora
of August, 1978. Both storms formed in the same general area, reached
an estimated peak intensity of 80 kts, weakened as they approached the
Windward Islands, and dissipated in the southeastern Caribbean Sea.
The annual seasonal summary article for 1978, as published in _Monthly
Weather Review_ (April, 1979, Vol. 107, No. 4), coincidentally was also
written by Miles Lawrence. To quote from that article: "Rapid
dissipation as Cora moved into the southeast Caribbean is not an
unexpected event in this area. The entrainment of continental air from
South America limits convective processes in the storm and strong
tradewind easterlies produced by the geographic heat low disrupt the
low-level circulation. Large-scale criteria were generally favorable
otherwise for intensification, and yet the circulation completely
disappeared within 24 hrs, which indicates the significance of
continental influences."
Another interesting tidbit from Miles' earlier report was the state-
ment that Cora was only the third Atlantic tropical cyclone to be
upgraded to hurricane status solely on the basis of satellite pictures.
Prior to 1978 the only Atlantic hurricanes so classified on the basis
of satellite imagery alone were Doris and Gladys of 1975. It's rather
interesting to realize that what is nowadays a routine occurrence was,
less than a quarter-century ago, considered a new and novel thing.
Hurricane Keith (TC-15)
28 September - 6 October
------------------------
Hurricane Keith was one of the two most intense hurricanes of the
season, the other being Hurricane Isaac. Both hurricanes reached
Category 4 status on the Saffir/Simpson scale with the MSWs peaking
at 120 kts. While Isaac remained far out in the mid-Atlantic, Keith
wandered slowly around the extreme northwestern Caribbean Sea, brushing
coastal regions of Mexico's Yucatan Peninsula and Belize as well as
some offshore islands before weakening and making landfall as a strong
tropical storm. The storm later re-intensified over the Bay of
Campeche and made a second landfall in northeastern Mexico as a strong
Category 1 hurricane. The official storm report on Keith, prepared
by Jack Beven, can be found at the following URL:
http://www.nhc.noaa.gov/2000keith.html>. I recommend that
interested readers first connect to TPC/NHC's website and read Jack's
report, which contains a tabular listing and plot of the analyzed
"best track" as well as plots of meteorological information.
Several months ago I asked Eric Blake if he would consider writing
a report on Keith for me. Eric agreed to do so, and the remainder of
the discussion of this hurricane is Eric's report basically as he sent
it with only minimal editing by myself. I'd like to extend a very
special thanks to Eric for writing the summary for Hurricane Keith.
Keith's origins can be traced to a tropical wave that emerged off
the west coast of Africa on 16 September. The wave continued moving
slowly westward without development as it encountered strong vertical
shear. The first signs of significant development were on 27 September
when convection flared near the center of the system in the western
Caribbean Sea. Aircraft reconnaissance found a 1004-mb tropical
depression on 28 September just east-northeast of the Honduran coast-
line, moving slowly in a general northwesterly direction. The
depression was under a well-defined upper anticyclone and it
intensified into a tropical storm the next day.
Keith then began a period of unexpected rapid intensification
shortly after 1800 UTC on the 29th when it was only about 125 nm from
land. Well-defined banding features were noted and it became a
hurricane on the 30th. Its pressure fell from 1000 mb to 939 mb in
about 36 hours and the storm reached its estimated maximum intensity
of 120 kts on 1 October. During this intensification a large area of
cloud tops with temperatures colder than -80 C were noted and a
circular, 15-20 nm wide eye emerged. The hurricane continued to drift
slowly to the west during this time, very near the coast of Belize with
its dangerous eyewall over the coastal islands. There were also
reports of the shallow Bay of Chetumal emptying with the constant north
to northwest winds.
The cyclone meandered for about two days off the Belize coast,
drifting slowly and erratically in a general westward direction. The
hurricane weakened gradually due to increasing easterly shear, some
mixing of cooler water from well below the surface of the northwest
Caribbean Sea, and increasing interactions of the inner core with land.
Keith made a first landfall as a Category 1 hurricane on Ambergris Cay
near 2300 UTC on the 2nd. However, this island likely received winds
of Category 3 strength or higher as it was in the hurricane's powerful
eyewall for about 24 hours before the hurricane weakened. Keith
diminished further into a tropical storm as it drifted westward,
crossing the Belize coastline with a MSW of 60 kts around 0300 UTC on
the 3rd between Belize City and Chetumal, Mexico.
The system continued to weaken as it headed inland, becoming a
tropical depression at 1200 UTC on the 3rd. It changed direction
slightly, moving more to the west-northwest. A ridge over the northern
Gulf of Mexico was providing a stronger steering current, and a gradual
acceleration took place over the next two days. The environment was
favorable for re-intensification over the Gulf of Mexico, and Keith
intensified into a strong Category 1 hurricane before landfall.
Weather radar from Tampico indicated that the system was well-developed
when it made landfall, with a pronounced eye and well-defined spiral
bands. The hurricane moved ashore about 40 km north of Tampico,
Mexico, around 1800 UTC on the 5th with maximum sustained winds near
80 kts.
Media reports indicate that 19 people died as a result of the storm,
with most of the deaths occurring in Belize and Nicaragua due to
flooding. Keith's slow motion led to incredibly large rainfall
totals, most notably over 813 mm at the Phillip Goodson International
Airport in Belize City. It is likely that higher amounts fell to the
east and north closer to the core of the stalled-out hurricane.
The maximum intensity of Keith is not an easy thing to determine.
Aircraft reconnaissance were only flying twelve-hour missions near the
probable time of maximum intensity, common practice in the northwestern
Caribbean. The Hurricane Hunter nearest the time of maximum intensity
only recorded a flight level wind of 118 kts at 700 mb, which normally
would not support an intensity of 120 kts in the best-track. However,
a dropsonde indicated peak winds of 153 kts in the southeastern eyewall
at a level of about 883 mb. This dropsonde did not report winds below
904 mb, though. In addition another sonde in the southwestern eyewall
recorded a wind of 122 kts about 30 m off the surface, and a wind of
140 kts at a level of about 70 m. Unfortunately, neither of these
dropsondes recorded winds near the surface. However, Keith's
convection was very intense and it seems plausible that the strong
winds at 30 m could have easily been transported to the surface.
The maximum flight-level wind at 850 mb was 133 kts, which would
reduce to about 115 kts at the surface. However, this maximum wind was
recorded more than 16 hours AFTER the minimum pressure was recorded in
Keith. It appears that the winds were actually increasing more at the
surface than at the 700-mb level and the normal flight-level-to-surface
reduction factors do not apply well to this hurricane, or perhaps any
rapidly-developing storm. Another interesting point is that objective
T-numbers on Keith exceeded 7.0 for a number of hours, equating to an
intensity of 140 kts or higher. This seems unlikely given twelve-hour
Air Force reconnaissance and is another example of the benefit of
having some ground truth observations.
The minimum pressure estimation of Keith requires some further
explanation. The lowest central pressure reported by a dropsonde was
942 mb, but this sonde reported a surface wind exceeding 40 kts. This
indicates that the sonde likely did not hit the area of lowest
pressure, and the National Hurricane Center has estimated a minimum
central pressure of 939 mb for the best-track database.
It is also worth noting that this storm gave forecasters a hard time
at the National Hurricane Center, especially while it was still in the
Caribbean Sea. Most of the forecasts issued had an error in both
intensity and track that were well above the ten-year mean. There does
appear to be some similarities with Hurricane Mitch in 1998, which was
in the same general location at the same basic time of year. A
comparison between the two storms shows that forecasts for both storms
were trying to take the storms too quickly to the north whereas both
hurricanes were generally stationary in the northwestern Caribbean for
a number of days, and neither was forecast to rapidly intensify.
***********************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for September: 3 tropical storms
1 hurricane
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory (CPHC
for locations west of 140W.) All references to sustained winds imply
a 1-min averaging period unless otherwise noted.
Northeast Pacific Tropical Activity for September
-------------------------------------------------
The average number of tropical storms forming in the Northeast
Pacific basin in September is about three with two reaching hurricane
intensity. This year four tropical cyclones formed during the month
but only one became a hurricane, the other three systems being short-
lived, minimal tropical storms. The hurricane, Lane, remained offshore
but did, in its later stages, move somewhat farther north than usual,
dissipating well to the west of San Diego, California. Tropical
Storms Miriam and Norman, although weak, did produce some slight
effects along portions of the Mexican coastline. Kristy was a very
brief storm which was a minimal tropical storm for only about 18 hours
on 2 September about halfway between Mexico and Hawaii.
Tropical Storm Kristy (TC-13E)
31 August - 3 September
-------------------------------
Tropical Storm Kristy was a short-lived, minimal tropical storm
which blossomed briefly about halfway between Hawaii and Mexico. The
storm was the easternmost developing disturbance associated with an
outbreak of enhanced convective activity in the Central and Eastern
North Pacific regions in late August, the others being Tropical Storm
John and an unnamed system south of Hawaii for which no warnings were
issued (which I dubbed "Mu" based on an opinion from Mark Lander that
tropical storm intensity was likely reached). (See the August summary
for discussions of those two systems.) The earliest mention by TPC/NHC
of the pre-Kristy disturbance seems to have been in a Tropical Weather
Outlook issued at 1700 UTC on 29 August. The system was located over
1100 nm southwest of Cabo San Lucas and contained minimal thunderstorm
activity.
Over the next couple of days the disturbance drifted slowly westward
and gradually became better organized. Advisories were initiated on
TD-13E at 2100 UTC on 31 August with the center located roughly 1425 nm
west-southwest of Cabo San Lucas or about 1325 nm east-southeast of
Hilo, Hawaii. The depression was sheared with the LLCC located to the
northeast of the main area of convection, and the initial intensity
was set at 25 kts. TD-13E remained essentially stationary for the
next day or so, being embedded in a large col region in the subtropical
ridge axis, and was slow to intensify. Last visible images on
31 August as well as a SSM/I overpass at 0605 UTC on 1 September showed
a good mid-level circulation, but at the lower levels the circulation
was broad with possible multiple vortices and little deep convection
near the main circulation center. A large convective burst developed
over the center around 01/0800 UTC which led to the MSW being bumped
up to 30 kts. This burst soon faded away, but a second burst occurred
during the morning and was a little better organized than the first
with a weak banding pattern around the center.
By 02/0000 UTC satellite intensity estimates from both TAFB and SAB
had reached 35 kts, so the depression was upgraded to Tropical Storm
Kristy at 0300 UTC. However, overnight the storm lost most of its
deep convection and did not intensify beyond minimal tropical storm
intensity. Convection fluctuated and remained somewhat disorganized,
but by 02/1800 UTC the low-level center was completely exposed and
Kristy was downgraded to a depression. The warning positions had
suggested a slow westward drift, but visible images warranted a
relocation of the center back eastward to near its point of origin.
By 0000 UTC on 3 September the LLCC had become elongated and separated
from a few spots of deep convection. The system appeared to be
embedded in the ITCZ, and the final advisory was issued at 0300 UTC.
Hurricane Lane (TC-14E)
5 - 14 September
------------------------
The final hurricane in the NEP basin this season formed from a
tropical wave which left the coast of Africa around 19 August. The
wave propagated westward across the Atlantic and Caribbean, reaching
the Eastern Pacific by the 30th. A 1008-mb LOW had formed by
3 September southwest of the Gulf of Tehuantepec. Ship reports early
on the 3rd indicated winds as high as 35 kts in squalls, but the low-
level center appeared to be displaced well to the southeast of the
strongest convection. The disturbance continued to move to the west-
northwest off the southern Mexican coast, and by the afternoon of the
4th showers and thunderstorms had become more concentrated near the
LOW which was located a couple hundred miles south-southeast of
Manzanillo. Advisories on TD-14E were begun at 1500 UTC on
5 September as the system exhibited some banding features and strong
convection near the estimated center which was located approximately
200 nm south-southwest of Manzanillo, Mexico. The depression was
upgraded to Tropical Storm Lane on the next advisory with satellite
intensity estimates solidly supporting tropical storm intensity;
however, a ship with call sign VRUZ9 had recently reported winds of
only 12 kts near the center, thereby casting some doubt upon the
Dvorak intensity estimates.
Lane continued to intensify in the near-term. Winds were up to
45 kts by 06/0300 UTC and were further increased to 50 kts at 0900 UTC.
Ship VRUZ9 reported winds of 27 kts about 70 nm north of the center at
0000 UTC, so the strongest winds were confined to a very small area
near the center. There was little evidence of any banding features,
and Lane's center early on 6 September appeared to be near the northern
side of a convective burst. Around 1200 UTC vessel ELX27 reported west
winds of 30 kts and a pressure of 1003 mb about 80 nm south of the
estimated position of the center. Some evidence of northeasterly
shear was beginning to be seen over the storm which put a halt for the
moment to the intensification process. Lane was embedded in a broad
low- to mid-level tropospheric trough which extended westward from the
coast of Mexico to near 120W. This steering environment caused the
cyclone's westward progress to slow and come to a halt. Visible
pictures around 1800 UTC revealed that the partially-exposed LLCC was
located to the southeast of the previous position estimates.
Tropical Storm Lane's appearance continued to deteriorate as it
became trapped in a large ITCZ-like band of low-level cyclonic flow and
convergence which competed with the storm's inflow. The northeasterly
shear also was detrimental to the storm, and the MSW was lowered to
40 kts at 0300 UTC on the 7th as the convection near the center had
become increasingly ragged. On infrared imagery Lane appeared as a
broad circulation with several clusters of deep convection but without
an inner core. Dvorak T-numbers had decreased to T2.5 from TAFB and
SAB by 1200 UTC, so the MSW was lowered to 35 kts in the 1500 UTC
advisory. Six hours later a banding feature west and south of the
center had developed so the intensity was increased to 40 kts; however,
at 0300 UTC on 8 September Lane was downgraded to a depression about
325 nm southwest of Manzanillo. The LLCC that was being followed
had popped out from under the convection during the afternoon and
progressively became less defined, eventually losing its identity
within the broad area of low pressure. NHC decided to hang on to
Lane as a tropical depression in the interest of avoiding potential
confusion in case the larger LOW should consolidate into a tropical
cyclone.
That decision proved to be a good one as by 0600 UTC Dvorak numbers
had jumped into the 45-55 kt range, based on the development of a
large, cold CDO-feature. It was impossible to determine from infrared
imagery if a LLCC had formed beneath the convection, but the CDO was
impressive enough that Lane was re-upgraded to a 35-kt tropical storm.
During the 48 hours from around 1200 UTC on 6 September through 1200
UTC on the 8th, Lane had described a somewhat erratically-shaped
counterclockwise loop. By 08/1200 UTC the tropical cyclone was moving
slowly northwestward under the steering influence of a large mid- and
upper-level ridge over northwestern Mexico. The MSW was increased to
55 kts at 2100 UTC based on unanimous Dvorak estimates of T3.5 from
the three agencies, and six hours later Lane was upgraded to a 65-kt
hurricane about 350 nm south of Cabo San Lucas on the tip of the Baja
California peninsula. A 25-nm cloud-filled eye had become visible
on satellite images. The storm at this time was moving northwestward
at 8 kts. The hurricane-force winds were confined to a very small
area near the center, but based upon 0000 UTC ship reports from waters
west of Manzanillo, the zone of gale-force winds was expanded out to
275 nm to the northeast--the coastal gales likely due to funneling
effects of the high terrain. Lane at this time was a large storm in
terms of gales: winds 34 kts or higher covered an area exceeding 500 nm
in diameter.
The rapid intensification trend which brought Lane up to hurricane
force leveled off some. By 1200 UTC on 9 September the MSW was raised
to 70 kts as the storm with its banding-type eye passed very near or
over Socorro Island where a minimum pressure of 973.7 mb was reported.
The hurricane reached its peak estimated intensity of 85 kts at 0000
UTC on 10 September when it was located approximately 200 nm southwest
of Cabo San Lucas. The minimum estimated CP was 970 mb, and Lane at
this time was sporting an eye 60 nm in diameter. Due to the large
size of Hurricane Lane, squalls with strong gusty winds, heavy rain,
high seas and pounding surf were forecast to occur along both coasts
of the Baja and along the Mexican west coast north of Manzanillo.
The peak intensity of 85 kts was maintained for 18 hours and then Lane
began to slowly weaken as it began to approach and move over cooler
SSTs. The MSW was dropped to 80 kts at 10/2100 UTC even though the
storm's convective pattern had become more symmetric. The cloud tops
were beginning to warm and Dvorak T-numbers were beginning to come
down. Lane continued to slowly spin down as it moved on its north-
westerly track well to the west of Baja California.
The storm was downgraded to a 60-kt tropical storm at 1800 UTC on
the 11th, and by 12/0000 UTC very little convection remained near the
system's center. The MSW was lowered to 55 kts on the 0300 UTC
advisory and continued to drop with each new advisory. The outflow
pattern became increasingly asymmetric and northward-oriented--evidence
of increased vertical shear over the system. A trough to the northwest
of the storm caused Lane to recurve to the north and northeast. During
the evening of the 12th a burst of convection occurred near the center
of Lane despite its being located over 21 C waters. Water vapor
imagery indicated that the burst was likely due to interaction with a
negatively-tilted upper-level shortwave trough passing just southwest
of the storm. Lane had weakened into a minimal tropical storm by
0600 UTC on the 13th when it reached the westernmost point of its track
about 450 nm west of Punta Eugenia, Mexico. The system was downgraded
to a depression at 1200 UTC, and the final warning on Lane was issued
at 0300 UTC on 14 September with the center of the swirl of low clouds
located about 250 nm west-southwest of San Diego, California. Moisture
from Lane spread over portions of California, Nevada, and Oregon.
Tropical Storm Miriam (TC-15E)
15 - 17 September
-------------------------------
Tropical Storm Miriam was a short-lived, minimal tropical storm
which brushed the tip of the Baja California peninsula. The Tropical
Wave log prepared by John Wallace does not connect Miriam with a wave
of African origin. The first mention of the pre-Miriam disturbance
in a TWO from TPC/NHC was at 1700 UTC on 8 September. An area of
disturbed weather was then located a few hundred miles south-southeast
of the Gulf of Tehuantepec, so it seems very possible that a tropical
wave from the Caribbean which had crossed Central America was the
precursor of Miriam. The disturbance moved slowly westward for the
next several days off the southern Mexican coast. On the 8th and 9th
the system seemed to be getting better organized, but it ran into a
less favorable environment on the 10th which put further development
on hold for a few days. As late as 14 September upper-level winds
were still somewhat hostile, but by the 15th conditions were becoming
more favorable for development and convection had become more
concentrated near the center. The first advisory on TD-15E was issued
at 15/2100 UTC placing the center about 175 nm west of Manzanillo,
Mexico--south of the mouth of the Gulf of California.
Convection associated with the depression disappeared during the
diurnal minimum but had begun to make a comeback early on the 16th.
Satellite intensity estimates were 35 kts at 0600 UTC, but ship C6LF9,
located near the center, reported only 20-kt winds and 1007.1 mb, so
the depression was not upgraded at 0900 UTC. The system was upgraded
to Tropical Storm Miriam at 1500 UTC with 35-kt winds although the
appearance in satellite imagery was not much improved over that of the
previous day. Miriam was located about 225 nm west-northwest of
Manzanillo moving slowly north-northwestward in the general direction
of Cabo San Lucas. Visible satellite images during the day showed an
unimpressive-looking system with ragged convection. An upper-level
cyclone over the central Baja was producing some southwesterly shear
over the storm. The last visible pictures of the day revealed an
exposed LLCC south of the previous position and southwest of the deep
convection. Nonetheless, Dvorak classifications were slightly higher
due to the certainty of the center, and Miriam's MSW was bumped up to
40 kts--the peak for the storm. The cyclone was centered about
125 nm southeast of Cabo San Lucas at this time and was moving north-
westward at only 5 kts.
Six hours later satellite intensity estimates were still 40 kts but
the MSW was dropped back to 35 kts based on a QuikScat wind analysis.
By 17/1200 UTC QuikScat data indicated no winds of tropical storm
force associated with the system and Miriam was downgraded to a
tropical depression near the tip of the Baja peninsula. Satellite
imagery during the afternoon revealed that the circulation had
dissipated in the southern Gulf of California and the final advisory
on Miriam was issued at 2100 UTC. The remnants of the depression were
still generating intermittent convection over the southern Gulf and
adjacent land areas. Heavy rains in association with Miriam likely
fell over portions of the Baja peninsula, but the author has learned
of no damage or casualties resulting from this tropical cyclone.
Tropical Storm Norman (TC-16E)
20 - 22 September
-------------------------------
Like Miriam, Tropical Storm Norman was a minimal tropical storm
which had a short career, but unlike the earlier storm, did make
landfall in Mexico--twice, in fact. Again, as was the case with
Miriam, I am unable, based on the information available to me, to
say with certainty whether or not Norman developed from a tropical
wave of African origin. The first mention of the pre-Norman system
in a TWO from TPC/NHC (1100 UTC on 16 September) indicated that a
westward-moving area of disturbed weather was located just southwest
of the Gulf of Tehuantepec. This suggests that the disturbance
likely did originate on the Caribbean side of Central America. By
very early on the 19th disturbed weather extended along and just off-
shore from an extensive area of the Mexican coastline: from the Gulf
of Tehuantepec to Cabo Corrientes. A weak LOW was embedded in the
disturbed area about 200 nm south of Manzanillo but was showing no
imminent signs of development. However, during the morning convection
began to increase and by afternoon was becoming fairly well-organized.
The 4:00 PM PDT Tropical Weather Outlook indicated that a tropical
depression could form within the next day or two.
The first advisory on TD-16E was issued at 0300 UTC on 20 September.
The initial location was roughly 150 nm south-southeast of Manzanillo.
Outflow had improved and central deep convection had increased with
a large area of very cold cloud tops of -85 to -88 C on the western
side of the center. Embedded in a weak steering flow pattern, the
depression was drifting northward at only 2 kts. At 1200 UTC ship
3ESU8 reported 38-kt winds and a SLP of 1001.5 mb, and at 1300 UTC
ship LADQ4 reported winds to 39 kts and a SLP of 1003.0 mb. Therefore,
TD-16E was upgraded to Tropical Storm Norman at 1500 UTC with the MSW
estimated at 40 kts. The center of Norman was just south of the
coast about 115 nm southeast of Manzanillo or about 75 nm west-
northwest of Zihuatanejo. The cyclone still exhibited very cold cloud
tops of -83 C and further strengthening was considered a possibility
before landfall. Norman at this time was moving north-northeastward
at 6 kts.
At 1800 UTC Norman's center was difficult to pinpoint but was likely
located on the Mexican coastline. Satellite intensity estimates
from TAFB, AFWA, and SAB were 45 kts, 45 kts, and 35 kts, respectively,
so the MSW remained at 40 kts. Almost immediately after making land-
fall, Norman began to track to the west-northwest parallel to and just
inland from the coast, likely due to a mid- and upper-level anticyclone
located over Mexico. The cyclone was downgraded to a depression at
21/0300 UTC and never regained tropical storm intensity even though
the center later re-emerged over water. Norman passed just to
the north of Manzanillo around 0600 UTC on the 21st with peak sustained
winds estimated at only 25 kts. By 22/0000 UTC the center of the
depression had moved back over the Pacific near Cabo Corrientes and
was moving at a slightly faster pace toward the northwest.
The MSW was increased slightly to 30 kts after the system had moved
back over water based on a 22/0105 UTC QuikScat pass. The QuikScat
data showed westerly rain-contaminated winds of 35 to 40 kts south of
the center, which equates to about 30-32 kts corrected surface winds.
A large convective complex was noted north of the center and also
inland over Mexico. While environmental conditions would have favored
some re-intensification, interaction with the Mexican landmass
inhibited any further strengthening of the depression. Norman
turned to the north after 22/0600 UTC, and surface reports and first
visible pictures on the 22nd indicated that the small circulation
center was making landfall near Mazatlan. After moving inland Norman
continued to move northward, and the final advisory was issued at
2100 UTC.
Some media sources reported that at least 8 persons died in Mexico
within 24 hours from a tropical depression on the Gulf coast and from
Tropical Storm Norman on the Pacific coast. There was no tropical
depression in the Gulf of Mexico during this period, but there was a
disturbance in the Bay of Campeche which on 19 September did appear to
be organizing rapidly at one point, prompting a reconnaissance flight
into the area. This area weakened on the 20th as the outflow from
Norman streamed across the region. In the city of Tapachula (in the
state of Chiapas), four persons died in mudslides and rockslides.
Tapachula lies along the extreme southeastern coast near the Guatemalan
border, so these fatalities were not associated with Norman. Neither
were two deaths which were reported in Veracruz state. However, there
were two deaths by drowning reported in Guerrero state which were due
to the heavy rains of Norman. The center of Norman made landfall in
the state of Michoacan which lies just to the west of Guerrero.
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for September: 3 tropical storms **
2 typhoons ++
2 super typhoons
** - one of these was treated as a tropical storm only by JTWC, and
another is included based upon Mark Lander's assessment that it
reached tropical storm intensity
++ - one of these (Sonamu) was not upgraded to typhoon status by JMA
NOTE: Most of the information on each cyclone's history presented in
the narrative will be based upon JTWC's advisories, and references to
winds should be understood as a 1-min avg MSW unless otherwise noted.
However, in the accompanying tracking document I have made comparisons
of coordinates with JMA (Japan) and the Philippines (PAGASA) when their
positions differed from JTWC's by usually 40-50 nm or more. A special
thanks to Michael V. Padua, owner of the Typhoon 2000 website, for
sending me the PAGASA and JMA tracks.
In the title line for each storm I plan to reference all the cyclone
names/numbers I have available: JTWC's depression number, the
JMA-assigned name (if any), JMA's tropical storm numeric designator,
and PAGASA's name for systems forming in or passing through their area
of responsibility.
Northwest Pacific Tropical Activity for September
-------------------------------------------------
An active September followed on the heels of an active August in the
Northwest Pacific basin. Five tropical cyclones were named by JMA
with four becoming typhoons. (This per JTWC's classification--JMA did
not upgrade Sonamu to a typhoon.) Two of the typhoons, Saomai and
Shanshan, reached super typhoon status as winds climbed to 130 kts.
(Again, this based upon JTWC's 1-min avg MSW values.) Typhoon Saomai
passed over Okinawa after weakening from super typhoon status and later
made landfall in South Korea. Shanshan spent its entire life east
of 165E--an unusual area for a super typhoon to occur. Early in the
month Typhoons Saomai and Wukong and Tropical Storm Bopha were all
progressing simultaneously for several days. Wukong passed over the
extreme southern tip of Hainan Island and made landfall in Vietnam.
Bopha followed a very unusual course, being driven southward by the
large circulation of Super Typhoon Saomai. The storm moved almost
due southward off the east coast of Taiwan and made landfall on the
northern end of Luzon.
Typhoon Sonamu was a very small typhoon which formed near Iwo Jima
and moved northward, remaining east of Japan. Also around mid-month
another small TUTT-induced system formed several hundred miles south-
east of Japan. No warnings were issued on this system, but Dr. Mark
Lander of the University of Guam believes that it reached tropical
storm intensity. A track is included for this system, which I have
designated with the Greek letter "Nu", in the cyclone tracks file.
Finally, near the end of the month, another weak system formed to
the north of Wake Island and was designated as Tropical Depression 27W
by JTWC. JTWC later upgraded this system briefly to tropical storm
status, but JMA carried it only as a depression; hence, it was not
named.
Super Typhoon Saomai (TC-22W / TY 0014 / Osang)
2 - 18 September
-----------------------------------------------
Saomai: submitted by Vietnam, is the Vietnamese name for the planet
Venus
Saomai was a long-lived typhoon which became the year's third super
typhoon in the NWP basin. The storm traced out a long trajectory from
its point of origin well to the east of the Marianas which took it
directly over Okinawa and eventually into South Korea. Saomai's peak
intensity of 140 kts (per JTWC) was reached while southeast of Okinawa,
but fortunately the storm had weakened considerably before striking
the island, although it was still a potent typhoon. The daily STWO
issued by JTWC on 1 September discussed an area of convection located
approximately 700 nm east of Guam which apparently had persisted from
the previous day. (Unfortunately, I cannot locate the STWO for 31
August.) Convection had been pulsating for a couple of days around
a LLCC, but the center was too weak to maintain the convection. An
upper-level ridge was over the area with a TUTT to the northwest.
CIMSS analysis indicated weak vertical shear over the disturbance and
the development potential was upgraded to Fair.
A Formation Alert was issued for the system at 02/0130 UTC.
Animated satellite imagery indicated improving organization during the
previous six hours with convection developing west of the LLCC.
Outflow over the disturbance was fair and vertical wind shear was weak.
The first warning on TD-22W was issued at 12/1200 UTC, placing the
center about 700 nm east-northeast of Guam. The system was smaller
than average (about 130 nm in diameter), and a 02/1057 UTC SSM/I pass
revealed deep convection increasing near the center and to the west.
The environment was favorable for strengthening and JTWC upgraded the
depression to a 35-kt tropical storm on the second warning (1800 UTC).
The tropical cyclone moved on a straight westerly course on 3 September
and began to intensify rather quickly. JMA upgraded the system to a
tropical storm at 03/0600 UTC and assigned the name Saomai. By
1200 UTC Saomai had developed a central cold cover with temperatures
to -84 C. Outflow was good over the system, and by 1800 UTC the storm
was approaching typhoon strength with both JTWC and JMA estimating
peak sustained winds of 55 kts (both 1-min and 10-min avg).
JTWC upgraded Saomai to a typhoon at 0000 UTC on 4 September with
the storm centered approximately 425 nm east-northeast of Guam. The
MSW was increased to 70 kts at 0600 UTC since a 04/0236 UTC TRMM pass
depicted a developing eyewall; however, infrared satellite imagery at
this time did not reveal a warm spot (indicative of eye formation).
Saomai continued to increase in intensity on the 4th with JMA upgrading
the storm to a typhoon at 1200 UTC. By 1800 UTC the MSW reached an
initial peak intensity of 90 kts (per JTWC) while JMA estimated the
maximum 10-min avg winds at 70 kts. A warm spot had become evident in
imagery; however, the storm was also showing some signs of increasing
vertical shear caused by an upper-level anticyclone to the northwest
of the typhoon. A TRMM pass at 04/2033 UTC indicated that much of
the convection had been sheared to the south of the LLCC, although a
narrow band of convection was wrapping into the center from the north.
JMA downgraded Saomai to a tropical storm at 0600 UTC on the 5th when
the storm was located about 85 nm northeast of Saipan (or about 200 nm
northeast of Guam), and JTWC followed suit six hours later.
By 1200 UTC Saomai was moving slowly southward, steered by a sub-
tropical ridge to its southwest. This southward motion continued until
around 0000 UTC on 6 September when the storm reached a point roughly
190 nm east of Guam. The MSW dropped to 55 kts (50 kts per JMA) and
maintained this strength for the next 48 hours. A 06/0758 UTC Quik-
Scat pass showed that the strongest winds were located in the southeast
quadrant. By 0600 UTC the storm had embarked on a northwesterly track
which it was to follow for over a week. Tropical Storm Saomai was
located about 80 nm east of Saipan at 1800 UTC where a pressure of
991 mb and sustained winds of 15 kts were recorded. Convection was
making a comeback with improved banding west and southwest of the
center. A low- to mid-level ridge to the northeast of the system
was the primary steering influence at this juncture. Around 0000 UTC
on 7 September Saomai moved through the Marianas island chain, passing
about 60 nm north of Saipan near Anatahan Island. The storm exhibited
a partially-exposed LLCC on the northern edge of the convection.
After passing the Marianas Saomai continued moving northwestward at
around 12-14 kts with little change in intensity or structure. Outflow
was good over the southern semicircle but an upper-level LOW to the
northeast was inhibiting outflow on the northern side. By 08/0000 UTC
the storm's organization had increased and a CDO about 140 nm in
diameter had formed. JTWC re-upgraded Saomai to a typhoon, placing the
center approximately 400 nm south of Iwo Jima. (JMA, however, did not
upgrade the storm to typhoon intensity for another 24 hours.) Hints
of a developing eye were seen around 0600 UTC, and JTWC had increased
the MSW estimate to 85 kts by 1800 UTC. Deep convection was present
over the LLCC and a large inflow was evident in satellite imagery.
Typhoon Saomai continued to intensify on 9 September as it plodded in
the direction of Okinawa. A 22-nm irregular eye had become visible
by 1200 UTC and the MSW was upped to 100 kts. The 1800 UTC warning
further increased the winds to 120 kts around a well-defined, 15-nm
diameter eye surrounded by intense convection. (JMA's maximum 10-min
avg wind estimate had reached 90 kts by this time.)
Saomai reached its peak estimated intensity of 140 kts at 1200 UTC
on 10 September when the 20-nm eye was centered 280 nm east-southeast
of Okinawa. (JMA's maximum 10-min avg wind at this time was 100 kts.)
50-kt winds extended 70 nm to the northeast of the center and 55 nm
elsewhere while gales covered an area almost 350 nm in diameter. Super
Typhoon Saomai possessed a broad circulation with a fairly tight,
intense inner core. The typhoon continued to make a beeline for
Okinawa but very fortunately began to slowly weaken. The MSW was
lowered to 130 kts at 11/0000 UTC, and by 1800 UTC on the 11th was
down to 110 kts. (JMA was reporting 90 kts.) At 1800 UTC Saomai was
centered 100 nm east-southeast of Naha Airport, moving toward the west-
northwest at 6 kts. A TRMM pass at 11/1647 UTC depicted an intense,
symmetric system with a 33-nm circular eye, and animated satellite
imagery revealed concentric eyewall development.
Typhoon Saomai continued to slowly weaken as it approached and
crossed Okinawa. By 12/0000 UTC the eye had become cloud filled and
defined solely by the convective bands. Kadena AB (WMO 47931) was
reporting northerly sustained winds of 27 kts with gusts to 44 kts.
A 12/0045 UTC SSM/I pass depicted a concentric eyewall with strong
banding to the south. At 0755 UTC Kadena AB was reporting northerly
winds of 48 kts with gusts to 76 kts and a SLP of 958 mb. The 20-nm
eye was centered at 12/0600 UTC only about 15 nm southeast of Okinawa
(presumably Naha Airport, since the previous JTWC warnings had used
that site as a reference point), and the estimated MSW was 100 kts.
(JMA's maximum 10-min avg wind had dropped to 75 kts by this time.)
The storm crossed over the central part of the island during the
late afternoon (local) of 12 September. At 0830 UTC the exact center
of Saomai's eye was located about 6 nm east-southeast of Kadena AB,
and by 1500 UTC had moved to a position about 36 nm north-northwest of
the base. Yoron Island (WMO 47942), north of Okinawa, reported
sustained winds (1-min avg) to 65 kts. By 1800 UTC the storm was
centered about 65 nm west-northwest of Naha Airport with the MSW
estimated at 90 kts (per JTWC). Yoron Island, which was located
beneath a strong convective band, reported 63-kt sustained winds (1-min
avg) and a SLP of 980.2 mb around 1800 UTC. Kadena AB reported peak
gusts to 45 kts and a pressure of 971.7 mb, and was still reporting
sustained winds of 28 kts (10-min avg) and gusts to 42 kts at 0000 UTC
on the 13th. The heaviest precipitation was confined to the eastern
semicircle of the typhoon at this time.
After passing Okinawa Typhoon Saomai continued moving rather slowly
to the northwest through a weakness in the subtropical ridge. The
storm remained in a more or less steady state intensity-wise on 13 and
14 September with the MSW in the 85-90 kt range (per JTWC) and the
maximum 10-min avg winds estimated at around 70-75 kts by JMA. At
13/0600 UTC the typhoon's center was located about 320 nm south of
Cheju Island, South Korea. A buoy (WMO 22001), located approximately
30 nm north of the center, reported 54-kt sustained winds and a SLP
of 962 mb. Six hours later the same buoy was about 15 nm east of the
typhoon's center and was reporting 45-kt sustained winds and a SLP of
968 mb. By 1800 UTC Saomai had slowed some in its forward motion and
was moving westward at 5 kts. Infrared imagery revealed an irregular,
ragged eye, and microwave imagery indicated a thin eyewall with a
larger band of convection south of the center.
Saomai reached the westernmost point of its long track at around
0600 UTC on 14 September when it was located approximately 185 nm east
of Wenchou, China. The storm had intensified slightly from 85 to
90 kts, and began to turn slowly to the north due to a mid-latitude
trough to its northwest. Infrared imagery showed that the system was
beginning to elongate along a north-south axis. Vertical shear was
still weak but forecast to increase as the storm moved farther to the
north. By 14/1800 UTC Saomai was indeed beginning to weaken as
evidenced by warming of the cloud tops and deterioration of the eye.
Microwave imagery revealed a partially-exposed LLCC with convection
being advected northward. After recurvature the weakening storm
initially moved slowly east-northeastward, then began to accelerate
to the northeast. At 1200 UTC on the 15th Saomai passed about 300 nm
east of Shanghai, moving north-northeastward at 20 kts with winds of
minimal typhoon intensity. Cloud tops had continued to warm and
what significant convection remained was isolated near the center of
the low-level circulation, although SSM/I imagery showed a very weak
convective band in the southeastern quadrant.
By 1800 UTC Saomai's center was approximately 80 nm southwest of
Pusan, South Korea, and continuing to accelerate toward the coast.
JMA had downgraded the typhoon to a tropical storm, and while JTWC
was still maintaining Saomai as a minimal typhoon, the remarks in
the warning indicated that the storm was beginning to undergo extra-
tropical transition. Animated water vapor imagery depicted cold air
associated with a major short-wave trough pushing into the system from
the coast of China. Saomai made landfall around 2030 UTC at a point
approximately 95 km west of Pusan. At 2100 UTC Pusan reported 36-kt
sustained winds from the south with a pressure of 979.5 mb. JTWC
issued their final warning on the system at 0600 UTC on 16 September
with the now-extratropical system located over the Sea of Japan about
170 nm northeast of Seoul, South Korea, and tracking rapidly just east
of due north at 28 kts. What convection remained was displaced north
of a fully-exposed LLCC. The extratropical remnants of Saomai
continued to move northward over the western Sea of Japan, passing
back inland near Vladivostok, Russia, and remained identifiable over
eastern Siberia for a few more days.
Strangely, I cannot locate any references to any damage or
casualties caused by this typhoon. If any should become available
later they will be reported in a future summary. I did receive some
rainfall amounts from Patrick Hoareau of Rennes, France. Naha (on
Okinawa) recorded 183 mm in the 48 hours ending at 13/0000 UTC.
Dinghai, in China's Zhejiang province, measured 102 mm in the 18 hours
ending at 13/0600 UTC--slightly more than half the monthly average of
190 mm. Kaesong, North Korea, recorded a 24-hour total of 147 mm
from 15/0000 to 16/0000 UTC. Also, the lowest pressure measured
during Saomai's passage across Okinawa that I could find referenced
in warnings from JTWC was 958 mb. I seem to recall an e-mail which
mentioned a 952-mb reading, but I can not find any record of this in
my files. If anyone can confirm this, I'd appreciate it if they
would let me know.
NOTE: In looking through my files I discovered an e-mail from Mark
Lander--which he posted late on 2 September--in which he disagreed
with the warning intensity reported in the JTWC warnings for the
early part of Saomai's history. I overlooked this when I prepared the
September cyclone tracks file back in October. I am including here
Mark's preliminary best track which he prepared for Saomai from 02/0000
to 03/0000 UTC.
DATE TIME (UTC) LAT LON MSW-1 min (kts)
-------------------------------------------------------------
00 SEP 02 0000 16.1 N 158.6 E 25 (JTWC: none)
00 SEP 02 0600 16.2 N 157.3 E 35 (JTWC: none)
00 SEP 02 1200 16.2 N 156.5 E 40 (JTWC: 25 )
00 SEP 02 1800 16.3 N 155.7 E 45 (JTWC: 35 )
00 SEP 03 0000 16.3 N 154.8 E 55 (JTWC: 35 )
Tropical Storm Bopha (TC-24W / STS 0015 / Ningning)
5 - 12 September
---------------------------------------------------
Bopha: submitted by Cambodia, is the name of a flower which is used as
a little girl's name
Tropical Storm Bopha certainly had the most unusual track of any
NWP basin tropical cyclone so far this year. The storm formed several
hundred miles to the southeast of Okinawa and ahead of the intensifying
Saomai. The storm moved west-northwestward and passed near Okinawa
just as Saomai was beginning to rapidly deepen into a super typhoon.
The large circulation of the intense Saomai drove Bopha on a very
unusual southward course parallel to the east coast of Taiwan and
eventually into northern Luzon. I am unable to trace the origin of
Bopha with certainty due to some missing STWOs. The storm may be
related to a disturbance which was mentioned on 1 September, located
about 450 nm southeast of Okinawa. Animated visible satellite imagery
showed disorganized convection sheared to the west of a LLCC. I do
not have the STWO for the 2nd, but the STWO for 3 September indicates
that this area of convection had dissipated. No tropical disturbance
was mentioned in the STWO for 4 September except the pre-Wukong system
in the South China Sea. Unfortunately, I am missing the STWO for the
5th, which was the day that PAGASA initiated warnings on a tropical
depression about 500 nm southeast of Okinawa at 0600 UTC, assigning
the name Ningning. JMA began including information on the depression
in their High Seas Bulletins at 1200 UTC while at the same time PAGASA
upgraded Ningning to a tropical storm.
JTWC issued a Formation Alert for the system at 05/1600 UTC,
followed by the first warning on TD-24W at 1800 UTC. JTWC estimated
the MSW at 25 kts, while JMA reported the maximum 10-min avg wind at
30 kts and PAGASA at 35 kts. JMA upgraded the system to Tropical
Storm Bopha at 06/0000 UTC when it was centered approximately 550 nm
southeast of Okinawa. The system initially moved slowly northeast-
ward before curving to the northwest as it came under the steering
influence of a low- to mid-level ridge to its northeast. It is
interesting that JTWC's intensity estimates were well under those
from JMA during the early portion of Bopha's history. JTWC finally
upgraded Bopha to a tropical storm at 07/0000 UTC when the system
was centered approximately 475 nm east-southeast of Okinawa. The
remarks in the JTWC warning indicate that the warning intensity
(35 kts) was based upon satellite current intensity estimates ranging
from 25 to 55 kts--JMA's 10-min avg wind estimate at the time was
50 kts. Animated satellite imagery depicted a fully-exposed LLCC with
convection sheared about 30 nm to the north. A 200-mb analysis
indicated that Bopha was under moderate vertical shear beneath the
subtropical ridge axis.
By 1800 UTC the tropical storm was centered about 200 nm east-
southeast of Okinawa and moving west-northwestward at 16 kts. The
center was still exposed and satellite intensity estimates ranged from
35 to 55 kts, but the MSW was increased to 45 kts, likely influenced
by a report of 38-kt sustained northerly winds from a ship west of
Bopha's center. Over the next 12 hours the convection increased in
areal extent and became more concentrated over the LLCC, and at 0600
UTC on the 8th Bopha reached its peak intensity of 55 kts (per JTWC).
(JMA's estimated maximum 10-min avg wind remained at 50 kts during
this period.) The storm was centered at this time about 50 nm south-
east of Naha, Okinawa, where 30-kt sustained east-northeasterly winds
were reported at the airport (WMO 47936). Bopha continued moving to
the west-northwest, passing just to the south of Okinawa. Kadena AB
reported a peak wind of 40 kts at 0926 UTC (not sure if this reading
is sustained or a gust). By 1800 UTC the cyclone was centered about
125 nm west of Okinawa--this proved to be the northernmost point of
its track. Six hours later Bopha was moving south-southwestward at
5 kts due to the influence of the larger and steadily-intensifying
Typhoon Saomai, located then about 700 nm to the east-southeast.
The tropical storm was also beginning to weaken. Microwave imagery
showed a ring of weak convection about the system with some stronger
cells wrapping into the LLCC, and QuikScat data indicated very weak
winds in the southeast quadrant and an elongation of the wind field.
Bopha continued to move south-southwestward roughly parallel to the
east coast of Taiwan, passing about 175 nm east of Taipei at 09/0600
UTC. The storm continued to weaken as it experienced shear from
Typhoon Saomai. By 0000 UTC on 10 September the storm was located
about 120 nm east-northeast of the southern tip of Taiwan. Winds had
dropped to 40 kts, but the JTWC warning remarked that the system had
moved into a more favorable environment. Convection became better
organized with a deep convective band on the western and southern sides
spiraling toward the center, and the MSW was upped to 50 kts at 0600
UTC and briefly to 55 kts once more at 1200 UTC. Bopha was at this
time located about 115 nm north of Port San Vicente, Luzon, still
moving south-southwestward at 11 kts.
However, as the cyclone approached northern Luzon, it ran into
increasingly stronger vertical shear and began to weaken. At 0000 UTC
on the 11th the center had just about reached the coastline of north-
eastern Luzon, and the MSW had dropped to 45 kts (40 kts per JMA).
The system was being sheared apart with the upper-level clouds
streaming to the west-southwest while the LLCC had begun to move to
the south-southeast. The JTWC warning for 11/0600 UTC indicated that
a synoptic report of 40-kt winds had been reported near the center
(which was over Luzon), but the location wasn't specified. Bopha
was downgraded to a tropical depression (by both JTWC and JMA) at
1200 UTC when the center was near Ilagan. The dissipating depression
subsequently turned eastward and moved back out over the Philippine
Sea with the final JTWC warning at 12/0000 UTC placing the center
about 125 nm east of Casiguran.
Typhoon Wukong (TC-23W / TY 0016 / Maring)
2 - 10 September
------------------------------------------
Wukong: submitted by China, is the king of the monkeys. Featured in
the classic novel _Journey to the West_.
While Super Typhoon Saomai and the weaker Tropical Storm Bopha were
dancing about in the open Pacific, Typhoon Wukong formed in the South
China Sea and pursued a fairly straight track westward across the
southern tip of Hainan Island and into northern Vietnam, becoming a
respectable 95-kt (per JTWC) typhoon along the way. An area of
convection formed on 1 September approximately 360 nm north-northwest
of Palau. Animated visible satellite imagery showed disorganized
convection sheared to the west of a LLCC. As noted in the discussion
of Tropical Storm Bopha above, I am missing the STWO for the 2nd.
However, PAGASA initiated warnings on the disturbance at 02/0000 UTC,
placing the center about 350 nm east-northeast of Catanduanes Island
and naming it Maring. Maring initially jogged to the north, then
took off on a westerly track towards Luzon. That the system was
poorly-organized and difficult to track is evidenced by several huge
"jumps" (i.e., relocations). At 03/0000 UTC Maring was relocated
approximately 180 nm to the west-northwest of its previous warning
position. The STWO issued by JTWC at 0600 UTC also mentions this
relocation to a position about 140 nm east of Luzon. JTWC at this
time was not treating the system as a depression but did assign a Fair
development potential.
The PAGASA warning on Maring at 1200 UTC placed the broad center
about 75 nm east-southeast of the northeastern tip of Luzon, but at
1800 UTC the depression's center was relocated to a position 200 nm to
the west-northwest, or about 75 nm north-northwest of Laoag on north-
western Luzon. And at 0000 UTC on 4 September Maring was relocated
yet again to a position approximately 165 nm west-southwest of Laoag.
In the meantime, the STWO from JTWC at 04/0600 UTC indicated that the
disturbance east of Luzon from the previous days had dissipated. The
remarks indicated that a LLCC had developed in the South China Sea
about 180 nm west of Luzon. This location is very near PAGASA's
0600 UTC position for Tropical Depression Maring. Whether this South
China Sea circulation (which ultimately became Wukong) is the same
disturbance noted east of the Philippines a few days earlier or a
completely new development is perhaps open to question.
As the day progressed the system appeared to weaken and PAGASA
issued a final warning at 04/1800 UTC. However, six hours later JMA
began treating the system as a tropical depression in their High Seas
Bulletins, and JTWC issued a Formation Alert at 05/0300 UTC, noting
that convection had intensified over the previous few hours near a
partially-exposed LLCC. JTWC issued the first warning on TD-23W at
0600 UTC on the 5th, locating the center about 350 nm south-southeast
of Hong Kong and essentially stationary. Also at 0600 UTC PAGASA
re-initiated warnings on Maring, upgrading it to a 35-kt tropical
storm. The system was located in an environment of moderate easterly
vertical shear, so intensification proceeded at a slow rate. A low-
level ridge to the south steered Maring/23W on a slow easterly track
initially, but after around 1800 UTC the system began to move to the
north. JMA upgraded the system to a tropical storm at 06/0000 UTC,
naming it Wukong. JTWC still had the MSW assessed at 30 kts while
PAGASA was reporting a peak 10-min avg wind of 40 kts. At this stage
Wukong exhibited a broad LLCC with a strong band of convection and
strongest winds to the south of the center.
JTWC classified Wukong as a tropical storm at 0600 UTC on the 6th
when the system was centered approximately 300 nm southeast of Hong
Kong. The storm was moving to the north-northwest at 5 kts and
gradually turned to a westward track as a subtropical ridge to the
north began to build. By 1200 UTC CIMSS satellite-derived winds
products indicated weak vertical shear with good diffluence over the
area, and significant intensification was not long in coming. The MSW
was up to only 40 kts at 1800 UTC (although JMA's 10-min avg wind
estimate was 50 kts), but convection had begun to increase in areal
extent and consolidate around the center. However, at 0000 UTC on
7 September JTWC abruptly upgraded Wukong to a 65-kt typhoon located
about 235 nm south-southeast of Hong Kong. Animated satellite imagery
indicated that the system had rapidly gained in organization, and a
06/1934 UTC TRMM pass depicted tightly curved convective bands. The
storm by this time was tracking westward at 9 kts, a course from which
it never significantly deviated for the rest of its life.
Although Wukong had rapidly strengthened from a minimal tropical
storm into a typhoon, the intensification trend levelled off and the
system remained a minimal typhoon for the next 24 hours. (JMA upgraded
Wukong to a typhoon at 07/1800 UTC.) Overall organization improved
even though convection weakened slightly. A 07/1311 UTC SSM/I pass
depicted eyewall convection around the system except for the southern
quadrant with a convective band to the southwest. Typhoon Wukong
passed about 200 nm due south of Hong Kong at 0000 UTC on 8 September.
Animated water vapor imagery revealed good outflow aloft over the
storm and the organization was improving. JTWC increased the MSW to
75 kts at this time and to 90 kts at 0600 UTC. (JMA's 10-min avg wind
estimate rose to its peak value for the storm's history--75 kt--at
0600 UTC.) A TRMM pass at 08/0224 UTC revealed a ragged eyed 45 nm
in diameter.
The typhoon exhibited a slight weakening around 1800 UTC, losing its
eye feature in infrared imagery. JMA decreased the intensity to 70 kts
but JTWC maintained the MSW at 90 kts. As Wukong continued on toward
the southern tip of Hainan Island it re-intensified some, reaching its
peak intensity of 95 kts (per JTWC) at 09/0000 UTC as it neared the
island. The estimated MSW was based on satellite intensity estimates
of 90 and 102 kts. Microwave imagery indicated a well-defined center
with deep convection consolidated in the southern semicircle. By
0600 UTC on the 9th Wukong was located over the extreme southern tip of
Hainan and moving westward at 10 kts. The storm was beginning to
weaken and the MSW was lowered to 75 kts. (JMA downgraded Wukong to
a 60-kt tropical storm at 0600 UTC.) Wukong's intensity continued to
decrease further as it plodded westward across the Gulf of Tonkin, and
JTWC dropped the MSW to 65 kts at 1200 UTC. By 0000 UTC on the 10th
the storm was nearing the coast of northern Vietnam, and although
microwave imagery indicated the redevelopment of a large eye, Wukong
was downgraded to a 60-kt tropical storm. All the convection was
located along the southern side of the LLCC. The tropical cyclone
made landfall and began to weaken quickly. At 10/0600 UTC JTWC issued
their final warning, placing the center of Wukong about 150 nm south of
Hanoi. The MSW was estimated at 45 kts, based on a synoptic report of
40 kts just north of the center. JMA issued one more bulletin, down-
grading the storm to a depression. The remnants of Wukong continued
moving westward toward central Laos and northeastern Thailand.
Media reports indicate that Wukong left 5 dead with one person
missing in Hainan province. Over 2700 homes and 70,000 hectares of
crops were destroyed while 240,000 hectares of crops were damaged and
nearly 2.5 million persons adversely affected by the typhoon. In
Vietnam's Ha Tinh province, where the storm made its final landfall,
two persons were reported killed and 69 injured. Wukong's heavy rains
and 60-kt winds destroyed nearly 3000 homes--leaving 10,000 homeless--
and blew the roofs off 5000 others. In addition 11,000 hectares of
rice were submerged, power lines downed, and some sea dyke systems
breached by the torrential rains and storm surge.
Tropical Cyclone "Nu"
13 - 18 September
---------------------
The discussion of this system is based almost completely upon
information supplied by Dr. Mark Lander of the University of Guam,
who supplied the track for this cyclone which was included in the
global cyclone tracks file. Mark's track first defines a weak
tropical depression at 0600 UTC on 13 September about 425 nm north-
west of Wake Island. Over the next day or two the system moved
rather quickly to the northwest, gradually turning to the north-
northwest. By 15/0000 UTC the cyclone had reached its point of
recurvature about 700 nm east of Tokyo. In Mark's opinion the system
had reached tropical storm intensity at this point. A visible picture
taken at 14/2230 UTC shows a small, bright convective area with very
pronounced spiral bands feeding into the CDO. Mark estimates that the
MSW was 40 kts around this time. An intermediate STWO issued by JTWC
at 14/2300 UTC mentioned this area and indicated that it appeared to be
developing rapidly. The system was given a Fair development potential
and a Formation Alert was issued at 15/0000 UTC. A recent QuikScat
pass supported the existence of a LLCC beneath the convection with
winds of 20-25 kts.
However, the small cyclone turned toward the east-northeast and
quickly weakened. Mark's track weakens the system to 30 kts by 1200
UTC, and JTWC cancelled the Formation Alert at 1800 UTC. Convection
had decreased significantly and the exposed LLCC had moved north of
the upper-level ridge axis beneath moderate westerlies. The weak
system continued moving generally eastward for about 24 hours and then
sprang back to life with another burst of convection. Mark estimates
that the system had regained tropical storm intensity by 1200 UTC on
16 September and that it reached its peak MSW of 45 kts at 1800 UTC
when it was centered approximately 900 nm east of Tokyo. An infrared
image taken at 1130 UTC reveals a circular area of cold cloud tops
seemingly over or very near the LLCC. Following this flare-up the
system began to weaken again and drifted toward the south and later
toward the west-southwest. The final entry in Mark's track at 0600
UTC on 18 September places the dissipating center about 950 nm east-
southeast of Tokyo.
Typhoon Sonamu (TC-25W / STS 0017)
14 - 21 September
-----------------------------------
Sonamu: Korean word for pine tree, contributed by the Democratic
People's Republic of Korea (North Korea)
An area of convection formed on 13 September roughly 400 nm south-
west of Iwo Jima and by early on the 14th had moved to a position
approximately 200 nm southwest of the island. JTWC issued a Formation
Alert at 0430 UTC for the system as convection had become increasingly
organized. Synoptic and scatterometer data indicated a possible
LLCC beneath the convection. Vertical wind shear was weak and the
environment was favorable for strengthening. By 0600 UTC animated
satellite imagery indicated that the system was organizing quite
rapidly and warnings were initiated on TD-25W. The depression was
moving east-northeastward at 9 kts in the general direction of Iwo
Jima. The MSW was increased to 30 kts at 1200 UTC and to 35 kts
at 1800 UTC when the cyclone was centered about 130 nm southwest
of Iwo Jima. (JMA had designated the system as a depression at
1200 UTC but did not upgrade it to a tropical storm until 0600 on
the 15th.) The minimal tropical storm was being steered northeast-
ward by a low-level ridge to the south but was forecast to begin
tracking northward after about twelve hours due to the influence
of a subtropical ridge to the east.
JTWC increased the MSW to 40 kts at 15/0000 UTC, and JMA upgraded
and named the system Sonamu at 0600 UTC. By this time Sonamu was
located about 75 nm south of Iwo Jima and the expected northward
turn was taking place. The storm was rather small with the radius of
gales estimated to be only 50 nm. Animated satellite imagery
around 1800 UTC indicated a possible developing eye and also a deep
convective band developing southeast of the vortex center; therefore,
the MSW was upped to 60 kts (JMA's maximum 10-min avg wind estimate
was 50 kts). Tropical Storm Sonamu continued to move toward the
north-northeast and had reached a position about 25 nm east of Iwo
Jima by 0000 UTC on 16 September. Animated satellite imagery depicted
a tiny cloud-filled eye only 3 nm in diameter with an associated
primary spiral band wrapping in toward the LLCC from the southwest.
JTWC upgraded Sonamu to a 65-kt typhoon based on the formation of the
eye and satellite intensity estimates of 55 and 77 kts. At 15/2300 UTC
Iwo Jima reported sustained winds of 21 kts (10-min avg) from the
northwest with gusts to 33 kts. (JMA increased their maximum 10-min
avg wind estimate to 55 kts, which was the peak for the storm's
history--that agency did not upgrade Sonamu to a typhoon.)
By 0600 UTC Typhoon Sonamu was located about 80 nm north-northeast
of Iwo Jima and moving northward at 12 kts. The island was then
reporting sustained southwest winds of 22 kts (10-min avg) with gusts
to 31 kts. The MSW was increased to 70 kts at 1200 UTC based upon
satellite imagery which revealed improving organization. The typhoon
was centered about 30 nm northwest of Chichijima Island which was
reporting 35-kt sustained winds (10-min avg). Sonamu continued to
track toward the north, accelerating to 20 kts by 17/0000 UTC when
it was centered about 300 nm south-southeast of Tokyo. Most of the
deep convection was to be found in the northeast quadrant while the
southwest quadrant was virtually convection-free. JTWC bumped the
MSW up to 75 kts at 0600 UTC on the 17th--this was the storm's peak
intensity per that agency's analysis. Animated visible satellite
imagery revealed improving organization and a 13-nm irregular eye.
Sonamu by this time was located about 200 nm southeast of Tokyo
and moving north-northeastward at 21 kts. The translational speed
had increased to 29 kts by 1200 UTC as the typhoon passed 170 nm east
of Tokyo. Sonamu was maintaining its intensity and exhibited a banding
eye with tightly curved bands.
The storm continued to move rapidly north-northeastward in advance
of a major shortwave trough over South Korea and eastern China. Sonamu
was able to maintain its intensity due to its tracking beneath an
upper-level ridge axis, but by 1800 UTC deep convection was beginning
to weaken as the storm moved over 20 to 22 C SSTs. The MSW was still
estimated to be 75 kts at 0000 UTC on the 18th, but visible satellite
imagery depicted a mid/high cloud shield extending several hundred
miles northwest of the vortex center, indicative of an extratropical
system. An upper-level wind analysis at 17/1800 UTC indicated that
Sonamu was situated beneath the polar front jet with winds of 60 kts
from the southwest. In addition water vapor imagery indicated a cold
air tongue pushing in toward the vortex from the southwest. Almost no
convection was left and JTWC declared Sonamu to be extratropical at
18/0000 UTC and issued their final warning, placing the center about
240 nm northeast of Misawa, Japan. The vigorous storm, however, was
still estimated to be packing winds of 75 kts (55-kt 10-min avg wind
from JMA) even as it transitioned into an extratropical cyclone. The
extratropical storm raced rapidly to the northeast for the next
24 hours, passing through the Aleutian Island chain into the Bering
Sea where it became quasi-stationary and remained for several more
days while slowly filling.
Super Typhoon Shanshan (TC-26W / TY 0018)
17 - 27 September
------------------------------------------
Shanshan: contributed by Hong Kong, China, is a fairly common pet name
for young girls
An area of convection formed on 15 September near 15N just west of
the Dateline. A QuikScat pass indicated a developing LLCC with 20-kt
sustained winds. JTWC issued a Formation Alert at 16/0230 UTC as
imagery indicated that deep convection was increasing near the LLCC
and low-level cloud lines were becoming evident west of the center.
The disturbance developed slowly and a second Formation Alert was
issued 24 hours later. The first warning on TD-26W was issued at
1200 UTC on the 17th, placing the center about 450 nm southeast of
Wake Island or about 400 nm north of Majuro Atoll in the Marshall
Islands. Convection was becoming better organized and a 17/0640 UTC
QuikScat pass indicated 20-25 kt winds near the LLCC. The depression
continued to slowly strengthen and JTWC upgraded the system to a 40-kt
tropical storm at 0000 UTC on 18 September. Satellite current
intensity estimates were 30 and 45 kts, and animated imagery depicted
rapid consolidation of the deep convection during the previous three
hours with a 34-nm CDO over the LLCC and a spiral band wrapping into
the center from the east. (JMA began issuing bulletins on the system
at 18/0000 UTC but did not upgrade it to a tropical storm until 1200
UTC.) The cyclone's center at 0000 UTC was located about 390 nm
southeast of Wake Island (or 475 nm north of Majuro) and was tracking
west-northwestward at 7 kts within a weakness in the subtropical ridge.
The MSW was increased to 50 kts at 0600 UTC and to 55 kts at 1200
UTC when JMA upgraded the system to a tropical storm and named it
Shanshan. Convective organization had continued to improve with an
increase in spiral banding wrapping in toward the LLCC. A TUTT north-
west of Shanshan was helping to enhance the outflow. Expanding areal
coverage of the deep convection with cooling cloud top temperatures
was observed over the next 18 hours, and JTWC upgraded Shanshan to a
typhoon at 0600 UTC on the 19th when the storm was centered roughly
200 nm southeast of Wake Island. Shanshan jogged northward a bit about
this time but soon resumed a slow, northwesterly motion. Hints of a
developing eye were seen at 1200 UTC, and by 1800 UTC a 25-nm
irregular, cloud-filled eye had developed. The typhoon was then
located about 175 nm east of Wake Island, and JTWC increased the MSW
estimate to 90 kts while JMA upgraded Shanshan to a typhoon with
maximum 10-min avg winds of 70 kts.
By 0600 UTC on the 20th Shanshan's winds had climbed to 100 kts (per
JTWC's warnings). The typhoon displayed a 7-nm diameter eye, and
animated water vapor imagery depicted good outflow aloft with a mid-
level ridge building northeast of the storm. Typhoon Shanshan
continued to intensify as it tracked slowly northwestward. The MSW
reached 125 kts at 1800 UTC when the eye was centered approximately
120 nm north-northeast of Wake Island. However, satellite imagery
revealed that the southern half of the eyewall had collapsed and
the storm's intensity plateaued at 125 kts for about 18 hours. But
by 1200 UTC on 21 September Shanshan had begun to strengthen again
and JTWC increased the MSW to 130 kts, thus qualifying Shanshan for
super typhoon status. The storm had excellent outflow in all quadrants
and a 25-nm round eye. Six hours later Shanshan reached its peak
estimated intensity of 135 kts, based upon satellite current intensity
estimates of 127 and 140 kts. The 17-nm diameter eye was then
centered about 275 nm north-northwest of Wake Island and was moving
north-northwestward at 8 kts under the steering influence of a mid-
level HIGH situated to the northeast. 50-kt winds extended outward
90 nm to the northeast and 50 nm elsewhere while gale-force winds
covered an area about 320 nm in diameter. (The peak 10-min avg wind
estimate from JMA was 95 kts from 21/1200 through 22/0600 UTC.
Super Typhoon Shanshan maintained its peak intensity for about
twelve hours and then began to slowly weaken. At 0600 UTC on the 22nd
the MSW was decreased slightly to 130 kts as the storm turned to
a northerly course. Six hours later Shanshan was moving slowly to the
north-northeast and convection was beginning to weaken. The storm
was downgraded from super typhoon status with the MSW being estimated
at 115 kts. A 22/0939 UTC SSM/I pass depicted concentric eyewalls with
convective bands north of the eye. The typhoon passed about 900 nm
west of Midway Island around 1800 UTC, still slowly weakening.
At 0000 UTC on 23 September the MSW was still estimated at 100 kts
although there was little convection in the southwestern quadrant.
By 0600 UTC Shanshan was beginning to experience increased vertical
shear from the southwest, and the forward motion had increased slightly
to 14 kts. Six hours later the MSW was down to 90 kts (JMA's maximum
10-min avg wind estimate was 75 kts) and Shanshan's translational speed
had increased to 17 kts. A 23/1342 UTC TRMM pass revealed an exposed
LLCC with all the convection to the north of the center.
By 24/0000 UTC Shanshan was a minimal typhoon moving quickly north-
eastward at 24 kts and was beginning to undergo extratropical
transition as it merged with a mid-latitude system to the north-
northwest. The final JTWC warning at 24/0600 UTC indicated that the
storm had become fully extratropical at a position about 600 nm west-
northwest of Midway. The winds were estimated at 60 kts and the storm
was moving northeastward at 33 kts. JMA was still treating Shanshan
as a minimal typhoon, but six hours later issued their final bulletin
and declared the storm to be extratropical. Over the next few days the
storm continued to move northward in the vicinity of the Dateline,
eventually turning northeastward and weakening to a 40-kt gale by
27 September a few hundred miles south of the Aleutian Islands.
While Super Typhoon Shanshan did not significantly affect any land
areas, it was notable for the location in which it occurred. According
to Mark Lander, who reviewed some studies of typhoon climatology, it
is highly likely that Shanshan was the first known storm to reach super
typhoon intensity north of 20N and east of 155E.
Tropical Storm (TC-27W)
28 - 30 September
-----------------------
Tropical Storm 27W was a short-lived tropical cyclone which popped
up in the waters north of Wake Island and moved northward for a couple
of days before dissipating. JMA treated the system as a tropical
depression only; therefore, no name was assigned. However, as was
the case with the other unnamed tropical storm (TS-28W in early
October), there were a couple of synoptic ship observations which seem
to support minimal tropical storm intensity. The cyclone had its
beginnings in an area of convection which developed about 200 nm north-
northwest of Wake Island on 27 September. A 27/1009 UTC SSM/I pass
(85 GHz data) indicated increasing organization with some banding
features developing, so JTWC upgraded the development potential to
Fair in a special STWO at 1400 UTC. This trend continued throughout
the day and a Formation Alert was issued at 2200 UTC. The LLCC
appeared to be embedded in the eastern extension of a monsoon trough.
JTWC issued the first warning on TD-27W at 1800 UTC on 28 September.
The depression was moving northward at 9 kts with increased convective
organization and cooling cloud tops. The system was upgraded to a
35-kt tropical storm at 29/0000 UTC when it was located about 500 nm
north of Wake Island. Satellite intensity estimates were 30 kts, but
a ship about 40 nm northwest of the LLCC reported winds of 35 kts.
The tropical storm was located in a moderate vertical shear environment
and the deeper convection was sheared northeast of the center. Another
35-kt ship report six hours later (from 60 nm northwest of the center)
sufficed to keep the system classified as a tropical storm for one more
warning cycle. An approaching mid-latitude trough was creating the
shear and also was steering the system to the north-northeast. The
center was exposed with the deeper convection about 17 nm northeast
of the LLCC.
The system was downgraded to a tropical depression at 29/1200 UTC
as it continued moving to the north-northeast and began to merge with
the frontal boundary ahead of the trough. By 1800 UTC on 30 September
the system had become extratropical and the final warning was issued
placing the center about 600 nm north of Wake Island or 775 nm west
of Midway.
***********************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for September: No tropical cyclones
NOTE: A low-pressure area which persisted in the Bay of Bengal for
several days in late August and early September moved inland near the
head of the Bay on 1 September. A bulletin from the IMD on 2 September
mentioned that a depression had formed over land and at 02/0300 UTC
was centered near 24N, 85W. This location is well inland to the
northwest of Calcutta and about 70 km south of Gaya. No references
were made to this system in any STWOs issued by JTWC and no track was
included in the accompanying cyclone tracks file.
***********************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for September: No tropical cyclones
***********************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for September: No tropical cyclones
***********************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for September: No tropical cyclones
***********************************************************************
SOUTH PACIFIC OCEAN (SPA) - South Pacific Ocean East of Longitude 160E
Activity for September: No tropical cyclones
***********************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the July, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
***********************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
in the following manner:
(a) FTP to: hrd-type42.nhc.noaa.gov [140.90.176.206]
(b) Login as: anonymous
(c) For a password use your e-mail address
(d) Go to "data" subdirectory (Type: cd data)
(e) Set file type to ASCII (Type: ascii)
(f) Transfer file (Type: get remote_file_name local_file_name )
(The files will be named with an obvious nomenclature--using
September as an example: sep00.tracks)
(g) To exit FTP, type: quit
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. If anyone wishes to retrieve any of the previous summaries,
they may be downloaded from the aforementioned FTP site at HRD. The
summary files are catalogued with the nomenclature: sep00.sum, for
example.
Back issues can also be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Tom Berg, Michael
Pitt, and Rich Henning):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.com> OR http://www.geocities.com/taifun00/>
http://www.hurricanealley.net/>
http://www.qisfl.net/home/hurricanemike>
http://www.met.fsu.edu/gsc/Docs/Grads/henning/cyclones/>
Another website where much information about tropical cyclones may
be found is the website for the UK Meteorological Office. Their site
contains a lot of statistical information about tropical cyclones
globally on a monthly basis. The URL is:
http://www.met-office.gov.uk/sec2/sec2cyclone/sec2cyclone.html>
TROPICAL CYCLONE REPORTS AVAILABLE
I have discovered that JTWC now has available on its website the
complete Annual Tropical Cyclone Report (ATCR) for 1999 (1998-1999
season for the Southern Hemisphere). Also, ATCRs for earlier years
are available also.
The URL is: http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 1999 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 1999
Atlantic and Eastern North Pacific cyclones are now available. In
addition storm reports are now available for some of the Atlantic
tropical cyclones in 2000.
The URL is: http://www.nhc.noaa.gov>
Prepared by: Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays)
***********************************************************************
***********************************************************************
|
Document: summ0009.htm
Updated: 29th December 2006 |
[Australian Severe Weather index] [Copyright Notice] [Email Contacts] [Search This Site] |