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Monthly Global Tropical Cyclone Summary November 2001
[Summaries and Track Data] [Prepared by Gary Padgett]
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Monthly Global Tropical Cyclone Summary November 2001 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
NOVEMBER, 2001
(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.)
***********************************************************************
NOVEMBER HIGHLIGHTS
--> Most active November on record in Atlantic with three hurricanes
--> Most intense hurricane since 1952 strikes Cuba
--> Much loss of life in Philippines from tropical cyclone rains
--> Scattered activity in the Southern Hemisphere
***********************************************************************
***** Feature of the Month for November *****
ROUNDUP OF THE 2001 ATLANTIC HURRICANE SEASON
---------------------------------------------
This month's feature is a potpourri of various topics relating to
the 2001 Atlantic hurricane season. I have arranged it into three
sections:
(1) Some interesting statistics concerning the active late season
(2) Brief review of subtropical/hybrid activity
(3) Links to official storm reports for June through September
cyclones with a few additional comments
1. Some interesting statistics concerning the active late season
Overall the 2001 Atlantic tropical cyclone season was one of the
more active ones on record, with 15 named storms, 9 hurricanes, and
4 intense hurricanes (Category 3+ on the Saffir/Simpson scale). The
above-normal overall activity for the season was due in large measure
to the very active period from October through early December. Prior
to 1 October there had been 8 named storms, 4 hurricanes, and 2 intense
hurricanes--about average, although the complete dearth of hurricanes
through the end of August was very unusual. However, the final two
months of the season produced 7 tropical storms and hurricanes--the
highest since 1887 when there 9 post-September cyclones (including two
which formed in December).
Another new record was the highest number of hurricanes forming
after 30 September. There were 5, breaking the previous record of
4 set in 1887, 1950 and 1969. With regard to post-August activity,
2001 set a new record for the highest number of hurricanes forming
after 31 August. There were 9, the previous high being 8 hurricanes
in 1969. Also, 2001 produced 11 tropical storms after August, the
first such occurrence since 1969. The season continued the string
of very active seasons which began in 1995, broken only by the quiet
El Nino season of 1997. Since the big turnaround in Atlantic tropical
activity in 1995, there have been 94 named storms, 58 hurricanes, and
27 intense hurricanes. By way of contrast, the previous 10-year
period (1985-1994) produced 90 named storms, 49 hurricanes, and 14
intense hurricanes.
2. Brief review of subtropical/hybrid activity
David Roth, a meteorologist at the Hydrometeorological Prediction
Center in Maryland, has provided me with a list of systems which he
classified as subtropical storms or depressions during 2001. David's
primary criterion for inclusion was classification of a system on the
Hebert/Poteat scale for subtropical cyclones. It should be clearly
understood that TPC/NHC does not always regard an ST-number assignment
on the Hebert/Poteat scale as a sufficient criterion for classification
as a subtropical cyclone. Many forecasters and researchers use the
terms "subtropical" and "hybrid" interchangeably, but NHC in practice
employs a much more restrictive definition of a "subtropical storm".
To be officially classified as a subtropical storm (either
operationally or in post-analysis), a system must have no evidence of
surface fronts and display quite well-organized convective banding.
The primary rationale for inclusion of subtropical cyclones
in the Atlantic "best track" database is the belief that many such
systems prior to the satellite era were treated as tropical cyclones,
and to not include them now would introduce a bias in the historical
data set. Some of the systems not classified operationally as sub-
tropical storms nor so classified by the end of the season may still
be reviewed for inclusion at a later date.
Six of the systems on David's list constitute portions of the life-
spans of named tropical cyclones. For four of these: Allison, Karen,
Noel and Olga, the official "best track" classifies a portion of the
track as a subtropical storm. For Allison and Noel, the subtropical
designation was added after-the-fact; Karen and Olga were operationally
designated as subtropical storms before being named as tropical
cyclones. David also included Dean and Gabrielle in his list. In the
case of Dean, the tropical storm near the Leeward Islands dissipated
and a very weak remnant LOW moved northward. This interacted with a
frontal trough, ultimately resulting in the redevelopment of a tropical
storm south of the Canadian Maritimes. As the system was
re-intensifying in the North Atlantic it possibly had some subtropical
characteristics, but the "best track" does not classify it as a sub-
tropical storm. The TPC/NHC advisories for Gabrielle make it plain
that the storm did exhibit some pronounced subtropical features, but
since the storm was being carried operationally all the while as a
tropical storm or hurricane, the "best track" does not attempt to
designate any portion of Gabrielle's history as a subtropical cyclone.
The other three systems on David's list include a system in late
April, another in early May, and a subtropical depression lasting
from 22-25 July. The April and May systems are described in the
global tropical cyclone summaries for those months. There were some
reports of gale-force winds associated with them, but the systems
did not display very strong tropical features and have not officially
been classified as subtropical storms. I have no further information
on the July subtropical depression except its dates and maximum wind
and minimum reported pressure--30 kts and 1008 mb.
3. Links to official storm reports for June through September cyclones
with a few additional comments
In the October and November summaries I have included links to
TPC/NHC's official storm reports for the tropical cyclones forming in
those months, plus a few comments about changes made to the operational
intensities during post-storm analyses as reflected in the official
"best tracks" (BT). I wanted to include the same information for the
earlier storms here for the benefit of interested parties.
Cyclone Link Author(s)
------------------------------------------------------------------------
Allison http://www.nhc.noaa.gov/2001allison.html> Stacy Stewart
TD-02 http://www.nhc.noaa.gov/2001two.html> Miles Lawrence
Barry http://www.nhc.noaa.gov/2001barry.html> Jack Beven
Chantal http://www.nhc.noaa.gov/2001chantal.html> James Franklin
Dean http://www.nhc.noaa.gov/2001dean.html> Lixion Avila
Erin http://www.nhc.noaa.gov/2001erin.html> Richard Pasch/
Daniel Brown
Felix http://www.nhc.noaa.gov/2001felix.html> Stacy Stewart
Gabrielle http://www.nhc.noaa.gov/2001gabrielle.html> Miles Lawrence/
Eric Blake
TD-09 http://www.nhc.noaa.gov/2001nine.html> Jack Beven
Humberto http://www.nhc.noaa.gov/2001humberto.html> James Franklin
(a) Tropical Storm Allison - The peak operational intensity of 50 kts
is retained in the BT. The biggest change for Allison is that
the system has been classified as a subtropical cyclone from
10/0000 UTC until it became extratropical at 18/0000 UTC. Most
of this time it was quite weak (a subtropical depression) with
winds of 25 kts or less, but reached subtropical storm intensity
for about 18 hours on 11 June when it re-intensified over south-
eastern Louisiana and southern Mississippi, and again for 12 hours
on the 17th when located south of the New England coast.
(b) Tropical Storm Barry - The primary change to the storm's intensity
in the BT was the downgrading of Barry to a tropical depression
from 0000 through 1800 UTC on 4 August. Reconnaissance aircraft
could find no evidence of gale-force winds, but since tropical
storm warnings had already been issued, it was decided to keep
Barry as a tropical storm unless it weakened further in order to
lessen confusion should the storm re-intensify, which of course
it did. The operational peak intensity of 60 kts at landfall has
been retained in the BT file.
(c) Tropical Storm Chantal - Tropical Depression 04 was upgraded to
Chantal in an intermediate advisory at 1200 UTC on 16 August.
A late-afternoon reconnaissance flight could find no closed low-
level center, so the storm was downgraded to a tropical wave at
17/0000 UTC. During the post-storm analysis it was concluded that
the depression likely had lost its circulation by 16/1200 UTC, so
the BT file reduces it to tropical wave status at that time.
However, even as a tropical wave the system had developed 35-kt
winds by 17/0000 UTC, and the BT shows it becoming a tropical storm
at 17/1200 UTC after a reconnaissance aircraft had closed off a
low-level center. The operational peak intensity of 60 kts has
been retained in the BT file.
(d) Tropical Storm Dean - There are not any noteworthy differences
between the operational and BT intensities for Dean. The early
peak of 50 kts and the latter one of 60 kts are both reflected
in the BT file. After the storm redeveloped south of the Canadian
Maritimes, advisories were re-started at 27/0900 UTC. The BT file
shows Dean as having regained tropical storm status and intensity
by 27/0000 UTC.
(e) Hurricane Erin - For Erin the only differences between the BT and
operational intensities concern the duration of the storm's peak
intensity. Operationally, Erin's peak MSW of 105 kts was main-
tained for 24 hours and at 100 kts or greater for 30 hours. How-
ever, the BT keeps Erin at 105 kts for 18 hours and at Category 3
status for 24 hours. Also, the storm was upgraded to a hurricane
at 1800 UTC on 8 September, but the BT delays the attainment of
hurricane status until 09/0000 UTC.
(f) Hurricane Felix - Very few differences--in the BT file Felix's
period of peak intensity (100 kts) was reduced from 18 hours to
12 hours.
(g) Hurricane Gabrielle - Again only minor adjustments to intensity.
The operational advisories gave the MSW at 14/0600 and 14/1200 UTC
as 60 and 50 kts, respectively. The BT reverses these, reporting
50 kts at 0600 UTC and 60 kts at 1200 UTC. As noted above, the
advisory discussions (mainly on 15 September) pointed out that
after crossing the Florida Peninsula and entering the Atlantic,
Gabrielle did not resemble a tropical cyclone, but rather looked
more like a subtropical cyclone or even an occluded frontal LOW.
However, since the cyclone was maintained in the advisories as a
tropical entity, the BT file likewise keeps Gabrielle as a tropical
system until it became extratropical on 19 September.
(h) Hurricane Humberto - As with the previous few tropical cyclones,
there were few changes implemented in the BT file as compared with
the operational MSW values. In the BT file, Humberto is shown as
reaching tropical storm intensity six hours earlier than in real
time. The first reconnaissance flight into Tropical Depression 10
on 21 September found the system somewhat weaker than satellite
imagery suggested. The satellite appearance early on the morning
of the 22nd implied a tropical storm, but the MSW was estimated at
a more conservative 30 kts in the 1500 UTC advisory. However, a
reconnaissance flight during the early afternoon found a 50-kt
tropical storm, so it was assumed that the surface MSW had "caught
up" with the satellite signature during the night. The BT file
also indicates that Humberto reached hurricane intensity six hours
earlier than in real time. The peak operational MSW of 90 kts has
been retained in the BT file.
***********************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for November: 3 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. Some information was also obtained from the monthly
summary for November prepared by the Hurricane Specialists and
available on TPC/NHC's website.
Atlantic Tropical Activity for November
----------------------------------------
As will be obvious to most readers of these summaries, I am way
behind schedule, just as I was last year following active Atlantic
and North Pacific seasons. Happily, the official storm reports
prepared by the staff of TPC/NHC for the Atlantic and Eastern North
Pacific basins have now appeared on NHC's website. So, just as I
did last year, I am not going to write much about the October and
November cyclones in those areas in order to facilitate getting
caught up and back on schedule. While the reports may not contain
quite as much detail about certain aspects of the storms as I might
have included, there is no need for me to spend time re-creating what
others have already accomplished. I shall confine my remarks about
the cyclones for the latter two months of the season to pointing out
a few interesting features and tidbits that were not mentioned in the
NHC reports. The reports are very nicely done and highly informative
with several figures and tables, including charts and maps of the
official analyzed "best tracks". I will include links to the specific
reports below in the section for each storm.
Over the period 1950-2000, the month of November has produced an
annual average of 0.5 tropical storms, 0.3 hurricanes, and 0.1 intense
hurricanes. November of 2001 was the most active month of November
ever observed, at least since 1851. Three tropical cyclones were
active during the month and all three reached hurricane intensity.
Michelle probably should count as an October named storm, but reached
hurricane intensity and intense hurricane status in early November.
November has produced two hurricanes on several occasions, but never
three. Michelle continued the trend seen in recent years of late-
season intense Western Caribbean hurricanes. Noel and Olga both
originated as subtropical storms in the Atlantic with Olga following
a very erratic track for over a week and keeping the tropical storm
season active into early December.
November Atlantic Hybrid Systems
--------------------------------
The subtropical North Atlantic during November was remarkable for
the high number of LOWs which formed and exhibited some signs of
beginning the process of evolving into a subtropical or tropical
cyclone. Only Noel and Olga made the transition, but some of the
others are worth mentioning.
(1) System of 7 - 9 November: A non-tropical low-pressure system
about 600 nm south-southwest of the Azores was mentioned in a
TWO issued by NHC. There was sort of an elongated area of low
pressure, and early on 8 November the northern portion of the
LOW made an attempt to close off an eye feature which was main-
tained for a few hours. At 0600 UTC a ship located about 30 nm
northeast of the center reported winds to 50 kts and a pressure
of 1001.9 mb. However, the eye disappeared and the circulation
rejoined its frontal band. (Most of this information came from
David Roth--a special thanks to David.) James Franklin of NHC,
however, indicated that he felt the ship report could very well
be in error, as it did not fit in with manual cloud track motions
in the vicinity. By the morning of 9 November the LOW was located
about 150 nm southwest of the Azores. Thunderstorm activity was
minimal and it was moving over colder waters. This was the last
reference to this system by NHC.
(2) System of 11 - 13 November: Another non-tropical LOW moved from
about 1100 nm east-southeast of Bermuda on the morning of the 11th
to a position 1000 nm west-southwest of the Azores early on the
13th. Gale-force winds occurred well east of the center but the
system did not develop significant subtropical characteristics.
(3) System of 14 - 17 November: A non-tropical low-pressure system
had developed by the morning of 14 November between the east coast
of Florida and the northern Bahamas. The system produced gusty
winds and heavy surf along the Atlantic coast of central Florida
northward to the Carolinas. The LOW initially moved slowly north-
ward just off the Florida coast, then turned eastward and by
midday on the 17th was located about 250 nm east of the northern
Bahamas, moving east-southeastward. Upper-level conditions
remained unfavorable for tropical development, but the potential
for such was mentioned in the TWOs issued by NHC.
(4) System of 17 November: A non-tropical LOW was located about 300 nm
east-northeast of Bermuda around midday on 17 November. The LOW
was moving east-northeastward and had shown some increased organ-
ization during the morning. However, conditions were unfavorable
for tropical development and the system was dropped from the TWOs
after the 17th.
(5) System of 18 November: Another non-tropical LOW was mentioned in
the TWOs issued by NHC on 18 November in the far eastern Atlantic
well south of the Azores. Like the two preceeding systems this
LOW was not located in an environment conducive to tropical cyclone
development.
I've saved the most interesting system til last. A small system
which looked like a small shear-type tropical cyclone formed in the
eastern Atlantic west of the Straits of Gibraltar. Mark Lander
discovered this system while looking for a possible developing
Mediterranean cyclone which Julian Heming had alerted him to. Mark
dubbed it a "Spaincane", although it was actually closer to Portugal.
David Roth, while looking at satellite pictures for the remains of
Hurricane Noel, also accidentally noticed this system. Following is
a partial track of the "Spaincane" which David sent to me:
Nov 6 - 2100 UTC 34.8 N, 11.6 W
Nov 7 - 0000 UTC 34.9 N, 11.7 W
Nov 7 - 0300 UTC 35.1 N, 11.8 W
Nov 7 - 0600 UTC 35.2 N, 11.9 W
Nov 7 - 1800 UTC 35.8 N, 13.1 W
Nov 7 - 2100 UTC 35.7 N, 13.4 W
Nov 8 - 0000 UTC 35.8 N, 13.8 W
Nov 8 - 0300 UTC 35.8 N, 14.1 W
David indicated that to him, it at least looked like a small-scale
tropical depression/storm on the tail end of a stationary front. Water
temperatures, however, were only around 18 C. Mark Lander stated his
opinion that he was "95% serious that this is a genuine tropical
storm!" Later, when David sent me his list of subtropical cyclones
for 2001, he briefly discussed the "Spaincane". David noted that the
system was not classifiable using the Hebert-Poteat scale since it had
no attachments to fronts aloft. It had the tropical characteristic
of being non-frontal, yet it was over cool SSTs with cold air aloft.
A few months ago I discussed this system during a telephone conver-
sation with Jack Beven. Jack was of the opinion that the small cyclone
did somewhat resemble a tropical system, but felt that it was quite
weak. If I learn anything further about this system, or at least get
some more opinions on it, I'll include them in a future summary.
Hurricane Michelle (TC-15)
29 October - 6 November
---------------------------
Hurricane Michelle continued the trend seen during the past few
years of late-season intense Caribbean hurricanes. Late-season
(October and November) hurricanes reaching Category 4 intensity on
the Saffir/Simpson scale were not all that uncommon during the decades
of the 1950s and 1960s. Between 1952 and 1966, seven hurricanes were
at Category 4 strength on or after 1 October: Fox (1952),
Hazel (1954), Greta (1956), Hattie (1961--Cat. 5), Flora (1963),
Hilda (1964), and Inez (1966). Between 1967 and 1994 there were only
two: Gladys (1975) and Joan (1988). Since 1995 there have been
six: Opal (1995), Mitch (1998--Cat. 5), Lenny (1999), Keith (2000),
Iris and Michelle (2001). Indeed, since 1998 the most intense hurri-
cane of the season has occurred on or after 1 October (with Floyd in
September of 1999 being co-equal with Lenny). Typical of November
tropical cyclones forming in the Western Caribbean, Michelle turned to
the northeast while still in the Caribbean, thus missing the Florida
Peninsula. However, the hurricane was the strongest to strike Cuba
since Hurricane Fox in late October, 1952. The storm spread
destruction from Nicaragua and Honduras and Jamaica through Cuba to
the Bahamas.
Comparing the official "best track" (BT) with the operational track,
there were more than the usual number of small (5-10 kts) adjustments.
Likely this is due to the fact that there was a lot of reconnaissance
data available to sift through during post-storm analysis, and also due
to Michelle's displaying the unusual characteristic of its peak winds
not coinciding with the lowest measured central pressure. The peak MSW
reported operationally was 115 kts from 03/1200 through 04/1800 UTC.
However, the BT reports the MSW at 120 kts at 0600, 1200, and 1800 UTC
on 4 November. The central pressure reported by reconnaissance air-
craft was in the range of 944-950 mb during this period while the
minimum central pressure for the storm's history--933 mb--occurred at
1800 UTC on 3 November. Operationally, tropical advisories on
Michelle were continued through 2100 UTC on 6 November. However, the
BT file indicates that Michelle had become extratropical by 06/0000
UTC.
The death toll from Michelle stands at 17 persons: 6 in Honduras,
5 in cuba, 4 in Nicaragua, and 2 in Jamaica. Additionally, 26 persons
have been reported as missing: 14 in Honduras and 12 in Nicaragua.
Widespread flooding was reported in Honduras and Nicaragua during the
storm's early stages with 100,000 people forced to flee their homes.
Some flooding was also reported in Costa Rica, and flash floods and
mudslides caused damage on Jamaica. In the Cayman Islands the damage
estimate was placed at $28 million, the damage mainly occurring on
Grand Cayman.
Cuba was hardest hit by Michelle. More than 12,500 houses were
totally destroyed with over 100,000 damaged. The sugarcane crop was
especially adversely affected with the estimated losses in exports
totalling $60 million (USD). Export losses in the citrus crop
industry were estimated at $27 million (USD). The banana and plan-
tain crops were largely destroyed in the three hardest-hit provinces
of Cienfuegos, Matanzas, and Villa Clara. (More information about
the effects of Hurricane Michelle can be found on the Relief Web's
website: http://www.reliefweb.int>. Click on the Natural Disasters
link, then the Hurricane Michelle link.)
The official TPC/NHC storm report on Hurricane Michelle, prepared
by Jack Beven, can be found at the following URL:
http://www.nhc.noaa.gov/2001michelle.html>
Hurricane Noel (TC-16)
1 - 7 November
-----------------------
Hurricane Noel was one of three late-season hurricanes in 2001 to
initially develop as a subtropical storm, the others being Karen and
Olga. However, unlike the other two, the pre-Noel cyclone was not
classified operationally as a subtropical storm. The system formed
from an occluded frontal LOW which gradually shed its fronts and
acquired a weak mid-level warm-core structure. During its early
stages the system was carried in the High Seas Forecasts issued by
MPC. The TPC/NHC "best track" (BT) starts the system at 0000 UTC on
4 November, classifying it as a subtropical storm. Convection, which
had been limited and confined to the northern semicircle, became more
symmetric and formed a ring around the center at a radius of about
60 nm. On the morning of the 5th a ship reported 65-kt winds, so NHC
initiated advisories on Hurricane Noel at 1500 UTC, located several
hundred miles south of Cape Race, Newfoundland. Within twelve hours
after being upgraded, cooler waters and increased shear were already
taking their toll on Noel, and the cyclone was downgraded to a tropical
storm at 06/0000 UTC. The storm had become extratropical by 1200 UTC
and was absorbed by a larger extratropical system later in the day.
The official TPC/NHC storm report on Hurricane Noel, prepared by
James Franklin, can be found at the following URL:
http://www.nhc.noaa.gov/2001noel.html>
Hurricane Olga (TC-17 / STS #2)
23 November - 6 December
--------------------------------
Hurricane Olga, the final tropical cyclone of the active 2001
season, formed from an initially non-tropical LOW which underwent
an evolution into a subtropical storm and eventually into a tropical
cyclone. Olga was the third Atlantic hurricane to originate as a
subtropical storm, Karen and Noel being the others. Noel, however,
was not classified operationally as a subtropical storm; hence, Olga
was numbered as Subtropical Storm #2 when advisories were initiated.
After making an unusual double-cyclonic loop east of Bermuda, Olga
was steered southwestward by a strong HIGH to its northwest to a point
near the Bahamas. This southwesterly track for a tropical cyclone
late in the season is unusual, but certainly not unprecedented. Some
other late-season or out-of-season hurricanes which have followed
southwesterly or southerly tracks in that general region include a
November hurricane in 1934; the famous "Yankee" Hurricane which struck
Miami in 1935; a hurricane in March, 1908, which struck the Leeward
Islands; Hurricane Alice in January, 1955, which also struck the Lee-
ward Islands; and more recently Hurricane Lili in December, 1984.
As it neared the Bahamas, Olga encountered shear which caused it to
weaken into a tropical depression. However, the shear had lessened
enough by early on 2 December that Olga was able to regain minimal
tropical storm intensity for about 48 hours, thus extending the 2001
tropical cyclone season several days into December. Such an
occurrence is uncommon but not all that rare. The last Atlantic storm
to actually form in December was Lili in 1984, but Tropical Storm
Karen in 1989 and Hurricane Nicole in 1998, both of which formed in
late November, were still operating as tropical cyclones in early
December.
Comparing the operational intensity estimates with the "best track"
(BT) values, there were few changes. The biggest difference between
the two concerns the classification of the storm during its early
stages. Operationally, the pre-Olga system was treated as a typical
non-tropical gale center in the High Seas Forecasts on 23 and early
24 November. Post-storm analysis (reflected in the BT file) indicates
that the system had acquired subtropical characteristics by 24/0000 UTC
with a comma-shaped cloud band extending east of a well-defined center
and gale-force winds extending outward several hundred miles to the
north. Later in the day a ship passed through the center and reported
a pressure of 989 mb. This report was the basis for initiating
advisories on Subtropical Storm #2 at 2100 UTC. However, the cyclone
had already taken on a distinctive tropical appearance in satellite
imagery with hints of an eye. The BT file now shows Olga becoming a
tropical storm at 1200 UTC on the 24th. The storm consisted of a small
tropical-like core within a larger extratropical cyclonic envelope.
The gale wind radii were much more typical of a non-tropical system,
and this was the rationale for classifying the cyclone as a subtropical
storm rather than a tropical cyclone at that juncture.
The storm gradually acquired more typical tropical characteristics
on 25 November and also intensified. The first tropical advisory on
the system, naming it Tropical Storm Olga, was issued at 1500 UTC on
26 November with the center located several hundred miles east of
Bermuda. Olga was upgraded to a hurricane six hours later, but the
BT file now indicates that Olga had reached hurricane intensity by
1200 UTC. One interesting little difference between the operational
and "best track" is the time of the peak intensity of 80 kts. In the
real-time advisories, Olga's MSW was estimated at 80 kts at 27/1800
and 28/0000 UTC. However, the BT reduces the intensity at those times
to 75 kts but raises the MSW to 80 kts at 27/0600 and 27/1200 UTC.
The official TPC/NHC storm report on Hurricane Olga, prepared by
Lixion Avila, can be found at the following URL:
http://www.nhc.noaa.gov/2001olga.html>
***********************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for November: 1 hurricane
Northeast Pacific Tropical Activity for November
------------------------------------------------
The final Northeast Pacific tropical cyclone of the 2001 season,
Hurricane Octave, was active during the first few days of November
far to the southwest of Baja California. However, Octave formed late
in October and is counted as an October system. A link to the
official TPC/NHC storm report for Octave (as well as all the 2001
tropical cyclones) was included in the October summary.
***********************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for November: 2 tropical storms **
1 typhoon
** - One of these systems was classified as a tropical storm by only
JTWC and PAGASA, and the other by JTWC only
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 some of the Asian warning centers 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. Also, a special thanks to
Huang Chunliang of Fuzhou City, China, for sending me tracks based on
warnings from the National Meteorological Center of China (NMCC), the
Hong Kong Observatory (HKO), and the Central Weather Bureau of
Taiwan (CWBT).
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 November
------------------------------------------------
Only one typhoon formed during the month, Lingling, but it was quite
destructive to the Philippines (where it was known as Nanang) and to
Vietnam. Two other tropical depressions developed which were both
classified as tropical storms by JTWC. These were never named by
JMA, but PAGASA named them Ondoy and Pabling, respectively, when they
entered that agency's AOR. PAGASA also classified Ondoy (28W) as a
tropical storm, but regarded Pabling (29W) as only a depression.
NOTE: Following the narratives for the three November cyclones is a
short addendum to the October summary.
Typhoon Lingling (TC-27W / TY 0123 / Nanang)
6 - 12 November
---------------------------------------------
Lingling: contributed by Hong Kong, is a fairly common pet name for
young girls
Nanang: PAGASA name, is a Filipino nickname
A. Storm Origins
----------------
A STWO issued by JTWC at 1900 UTC on 3 November noted that an area
of convection had developed and persisted approximately 120 nm east-
southeast of Yap. Animated infrared satellite imagery indicated little
organization of the convection. A morning surface analysis revealed
that the disturbance lay in a monsoon trough with no closed LLCC. A
200-mb analysis, however, showed that the convection was located in a
favorable environment for intensification with good diffluence under
the subtropical ridge axis. Satellite imagery the next day indicated
the presence of multiple LLCCs within a broad circulation. JTWC
upgraded the development potential to fair at 1400 UTC since an
improvement in the organization of the convection had been observed.
By 0600 UTC on the 5th the disturbance had moved westward and was
located west of Yap, still showing evidence of multiple circulation
centers. JTWC issued a TCFA at 05/2000 UTC. The subject area of
interest was a large monsoon depression centered roughly 215 nm east-
northeast of Mindanao. A 05/1359 UTC TRMM pass depicted convection
around the periphery with sparse convection near the center--a typical
characteristic of a monsoon depression. The system was still situated
in a favorable environment with divergence aloft.
JTWC initiated warnings on Tropical Depression 27W at 06/0000 UTC
with the center approximately 90 nm east-northeast of Mindanao, moving
westward at 6 kts. PAGASA also began issuing bulletins at the same
time and named the system Tropical Depression Nanang. Both warning
centers estimated the intensity at 25 kts. PAGASA upgraded Nanang to
a tropical storm at 0600 UTC as the system's organization continued to
improve with an increase in convection as it neared the Philippines.
By 1200 UTC Nanang's center was near the Leyte Gulf. JTWC upped the
MSW to 30 kts, although the coverage of deep convection had been
reduced somewhat with the majority confined to the western semicircle.
JMA upgraded the depression to Tropical Storm Lingling at 1800 UTC with
the center located over southern Leyte Island. CI estimates at the
time were around 30 to 35 kts. As Lingling/Nanang continued to move
westward through the Philippine Archipelago, convective organization
continued to improve with impressive outflow noted over the northern
quadrant. At 0000 UTC on 7 November, both JTWC and NMCC upgraded the
cyclone to tropical storm status with the center located over northern
Cebu island.
B. Track and Intensity History
------------------------------
Lingling/Nanang's intensity hovered near or just above minimal
tropical storm intensity on 7 November as it moved generally west-
northwestward through the Philippine Islands, steered by a low to
mid-level ridge situated near the southern coast of China. The
system's organization gradually improved and water vapor imagery
depicted good outflow, especially to the north. At 1200 UTC the
center was located near northern Negros Island and by 0600 UTC on the
8th was over northwestern Panay Island. Tropical Storm Lingling/Nanang
maintained its deep convection as it passed through the Philippines but
remained loosely-organized. JTWC upped the MSW to 45 kts at 0000 UTC,
and by 0600 UTC some CI estimates were reaching 55 kts. At 1200 UTC
on the 8th the cyclone's center was just south of the island of
Mindoro. JTWC increased the MSW to 55 kts as the system continued to
become better organized with both equatorward and poleward outflow
channels.
A TRMM pass at 08/2239 UTC revealed a banding feature wrapping
around the southern periphery of the storm. By 09/0000 UTC the center
of Lingling/Nanang had moved through the Mindoro Strait into the South
China Sea at a point about 185 nm southwest of Manila. Satellite
intensity estimates had reached 65 kts so JTWC upgraded the storm to
typhoon status. Typhoon Lingling continued its slow westerly to
west-northwesterly march through the South China Sea on 9 November
as convection continued to increase in coverage and organization. JTWC
increased the MSW to 90 kts at 1800 UTC and further to 100 kts at 0000
UTC on 10 November. Lingling reached its peak intensity of 115 kts
at 0600 UTC and maintained it for 24 hours. The storm at this time
was located roughly 365 nm west-southwest of Manila or about 320 nm
east of the Vietnamese coast. JMA estimated the minimum central
pressure at 945 mb, and gales reached out 170 nm in all quadrants and
up to 250 nm in the northwest quadrant. Storm-force winds were
estimated to extend outward 80 nm from the 25-nm diameter eye.
Lingling was a rather strong typhoon for the South China Sea to
experience so late in the year.
The storm slowly weakened on the 11th as it approached the coast of
Vietnam. The ridge to the north remained intact and steered Lingling
on a fairly straight westward course. The typhoon made landfall just
south of the city of Qui Nhon around 11/1930 UTC with winds estimated
at 95 kts, gusting to 115 kts. Lingling was downgraded to a 60-kt
tropical storm at 0000 UTC on 12 November, and JTWC issued their final
warning on the cyclone at 0600 UTC. The MSW had dropped to 45 kts and
satellite imagery indicated that Lingling was rapidly weakening over
land about 110 nm west of the coast. JMA continued tracking the system
for 12 more hours before dropping it from their bulletins.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
NMCC's peak 10-min avg MSW estimate of 100 kts was in excellent
agreement with JTWC's peak 1-min avg MSW of 115 kts. HKO's peak of
95 kts was just a little lower, but was reported for only one 6-hour
cycle while NMCC's 100-kt peak was maintained for 24 hours. JMA's
maximum 10-min mean wind was 85 kts from 10/1200 through 11/1200 UTC.
There were some interesting differences in the intensity estimates at
11/1800 UTC--the final warning time prior to landfall when Lingling's
center was just off the coast of Vietnam. JTWC reported 95 kts, based
on a rather wide spread of CI numbers ranging from 4.5 (77 kts) to
5.5 (102 kts). NMCC agreed closely with JTWC, their estimate being
80 kts (10-min avg). HKO, however, was substantially lower at 65 kts,
and JMA even lower at 55 kts, dropping the intensity 25 kts from the
80 kts reported six hours earlier. (Typhoon Lingling had departed
PAGASA's AOR prior to reaching its peak intensity.)
D. Damage and Casualties
------------------------
Typhoon Lingling/Nanang was a very deadly event in the Philippines.
I have located sources quoting varying numbers of deaths. The Annual
Tropical Cyclone Report prepared by JTWC reports 171 confirmed deaths
and 118 missing. A report on the website of ReliefWeb from the Office
for the Coordination of Humanitarian Affairs (OCHA) states that over
200 persons were killed with almost as many missing and presumed dead.
The majority of the deaths seem to have occurred on the small resort
island of Camiguin lying just west of northern Mindanao. Cloudbursts
during the night created widespread flash flooding which caught people
while they were sleeping. Over 40,000 persons were displaced by the
flooding with 1000 homes destroyed and almost 3000 damaged. Total
damage in U. S. dollars was estimated at $22.7 million.
In Vietnam where Lingling made its final landfall the death toll was
much lower, due in part to evacuation of thousands of residents in the
path of the storm. The highest Vietnamese death toll located by the
author was 20, with 131 persons reported as injured. Even though the
death toll was relatively low, Lingling was a destructive typhoon to
Vietnam. Over 1000 houses were destroyed with several thousand more
damaged. Heavy rains were also a big factor in the damage sustained
by Vietnam from the storm. Over 10,400 hectares of rice paddies were
inundated and destroyed while almost 19,000 hectares of subsidiary
crops were destroyed by flooding. Over 30,000 banana trees were
destroyed, and the sugarcane and tobacco crops were hard hit also.
Almost 40,000 hectares of shrimp ponds were damaged and over 1400 small
boats were swept away. In addition, much soil erosion was caused by
the typhoon's heavy rains. The total damage estimate in Vietnam
resulting from Typhoon Lingling was placed at $37.3 million in U. S.
dollars. (More information on the effects of Lingling can be found at
the following URL: http://www.reliefweb.int>. Click on the Natural
Disasters link on the left side of the screen.)
Tropical Storm (TC-28W / Ondoy)
17 - 25 November
--------------------------------
Ondoy: PAGASA name, is a Filipino nickname
A. Storm Origins
----------------
An area of convection with an associated weak LLCC had developed by
14/0600 UTC about 170 nm west-southwest of Pohnpei. The disturbance,
embedded in the monsoon trough, displayed unorganized, cycling
convection which was limited to the southern periphery of the LLCC.
Upper-level conditions were marginal, but were forecast to become more
favorable as a TUTT located to the east continued moving westward. At
15/0600 UTC the disturbance was relocated to a position about 240 nm
southwest of Pohnpei. By 0600 UTC on the 16th the system was located
roughly 300 nm southwest of Chuuk. Convection was getting better
organized, outflow was fair, and shear was weak; therefore, JTWC
upgraded the development potential to fair. A few hours later, at
1400 UTC, JTWC issued a TCFA. The disturbance was then located about
470 nm southeast of Guam with a banding feature beginning to form in
the northeast quadrant.
The system, which consisted of a broad circulation embedded in a
monsoon trough, was relocated once more at 17/0600 UTC to a position
approximately 320 nm south of Guam. Also at 0600 UTC, JMA classified
the disturbance as a 30-kt depression. (JMA never upgraded the system
to a tropical storm and maintained it as a 30-kt depression for its
entire life.) JTWC re-issued the TCFA at 1400 UTC, and at 0600 UTC
on 18 November the depression was located approximately 200 nm south-
west of Guam. Animated multi-spectral satellite imagery revealed
an elongated LLCC with cycling convection near the circulation.
Conditions remained favorable for further intensification, and at
1200 UTC JTWC issued the first warning on Tropical Depression 28W.
The depression at the time was centered about 160 nm southwest of
Guam, moving northwestward at 7 kts with an initial intensity of
25 kts.
At 1200 UTC on 19 November TD-28W was located approximately 290 nm
north-northeast of Yap, moving west-northwestward at 9 kts. The MSW
was still estimated at 25 kts, and a SSM/I pass indicated little
improvement in overall organization. The depression lay under the axis
of a near-equatorial ridge with fair outflow and weak vertical shear,
so further intensification was considered likely. JTWC upped the MSW
to 30 kts at 20/0000 UTC when the depression's center was located
roughly 300 nm north-northwest of Yap. Satellite imagery indicated
a partially-exposed LLCC just southwest of deep convection. At 0600
UTC the system passed about 420 nm north of Palau, moving westward at
a rather quick 16 kts. By this time TD-28W had entered PAGASA's AOR
and had received the name Ondoy. JTWC upgraded Ondoy/28W to a tropical
storm at 1200 UTC based on CI estimates of 30 and 35 kts. The
cyclone's motion had changed to west-southwesterly at a slower pace
of 9 kts.
B. Track and Intensity History
------------------------------
Tropical Storm Ondoy/28W reached its estimated peak intensity of
40 kts (per JTWC's analysis) at 1800 UTC on 20 November when located
about 400 nm north-northwest of Palau. At 21/0000 UTC satellite CI
estimates were 35 and 45 kts, but imagery revealed a partially-exposed
center southwest of the deep convection, so JTWC decreased the
intensity to 35 kts. (Interestingly, PAGASA upgraded Ondoy to tropical
storm status at this time.) At 1200 UTC intensity estimates were 25
to 30 kts, so JTWC downgraded Ondoy/28W back to tropical depression
status. The system was then located about 325 nm east-southeast of
Catanduanes Island, moving west-southwestward at 16 kts. The JTWC
warning at 21/1800 UTC reported that the depression was moving north-
northwestward, but the next warning relocated the center 95 nm south-
southwest of the previous warning position. Over the next day or so
the center of Ondoy/28W dropped farther to the south, then moved north-
westward and later northeastward, completing a loop. This erratic
motion was likely caused by interaction with equatorial westerlies.
During this period central convection decreased in coverage and
organization and unfavorable vertical shear increased.
At 23/1200 UTC the depression's center was relocated to a position
about 275 nm east of Samar Island. Animated infrared imagery depicted
a large, broad area of convection that was showing signs of increasing
near the center of the low-level circulation. However, Ondoy/28W never
regained its intensity and continued to move generally north-
northeastward. JTWC issued their final warning on the system at 1800
UTC on 24 November. Ondoy/28W was located about 400 nm southeast of
Okinawa and was moving northward at 21 kts. The depression had by
that time lost its tropical characteristics and was declared extra-
tropical. However, PAGASA was still classifying Ondoy as a tropical
storm and issued warnings on the system until 25/1200 UTC when it was
downgraded to a depression.
C. Comparisons between JTWC and Other Centers
---------------------------------------------
JMA never estimated winds higher than 30 kts, which was the reason
Tropical Storm 28W never received a name from the official WMO naming
list. This does not represent a significant difference as compared
with JTWC, whose peak 1-min avg MSW for the storm was only 40 kts, and
that for only one 6-hour period. Neither did NMCC upgrade the system
to tropical storm status. PAGASA was the more liberal warning center
with Ondoy/28W, treating it as a tropical storm for 4 1/2 days. The
peak 10-min avg MSW estimated by PAGASA was 40 kts from 22/0600 through
25/0600 UTC. Interestingly, PAGASA upped the intensity of Ondoy to
40 kts twenty-four hours after JTWC had downgraded the system to a
tropical depression. A 10-min avg wind of 40 kts would correspond to
1-min avg MSW of 45 kts. I do not know if this discrepancy was based
upon a differing interpretation of satellite imagery or if PAGASA was
privy to some synoptic reports unavailable to JTWC and JMA.
D. Damage and Casualties
------------------------
No reports of any damage or casualties resulting from Tropical Storm
Ondoy/28W have been received.
Tropical Storm (TC-29W / Pabling)
18 - 24 November
----------------------------------
Pabling: PAGASA name, is a Filipino nickname
A. Storm Origins
----------------
An area of convection had begun to organize around 0600 UTC on
16 November approximately 200 nm northwest of the island of Borneo.
Persistent convection was organizing around a developing LLCC. A
15/2204 UTC QuikScat pass had revealed the existence of a broad and
elongated circulation while CIMSS analysis indicated fair outflow with
weakening shear over the region. The disturbance drifted westward
during the next two days with little change in organization. At 0600
UTC on the 18th the system was located about 280 nm northeast of
Singapore. A surface analysis at 18/0000 UTC revealed a broad LLCC
on the southern end of a northeast monsoon surge with persistent but
still unorganized convection. A SSM/I pass at 18/1122 UTC depicted
a possible banding feature, therefore, JTWC issued a TCFA at 1700 UTC.
The disturbance was located roughly 230 nm northeast of Singapore at
the time. JMA began classifying the system as a 30-kt depression at
1800 UTC, an intensity which was maintained in their High Seas
Bulletins throughout the depression's history.
By 19/0600 UTC the disturbance had begun to drift back toward the
east--it was then located about 310 nm east-northeast of Singapore.
A 19/0221 UTC SSM/I pass depicted a convective banding feature with
the LLCC southeast of deep convection. At 1700 UTC JTWC re-issued the
TCFA for the system, which by then was located about 350 nm east-
northeast of Singapore. Deep convection had continued to cycle and
was sheared to the northwest of the LLCC. JTWC issued their first
warning on Tropical Depression 29W at 20/0600 UTC with an initial
intensity of 25 kts. The depression was centered approximately 500 nm
northeast of Singapore and was moving north-northeastward at 8 kts.
At 1200 UTC an amended warning was issued which relocated TD-29W's
center about 95 nm to the southeast of the original warning position.
A 20/1055 UTC SSM/I pass had depicted a weak, exposed LLCC. However,
a QuikScat pass shortly afterward indicated a well-defined vortex
with a 30-kt westerly wind component. The depression was upgraded to
Tropical Storm 29W at 0000 UTC on 21 November. The cyclone's center
at the time was located approximately 300 nm west-southwest of the
southern tip of the island of Palawan, moving east-northeastward at
4 kts.
B. Track and Intensity History
------------------------------
Tropical Storm 29W tracked east-northeastward through most of the
21st, although by 1800 UTC its forward motion had slowed and it was
drifting slowly northward. A 21/1042 UTC SSM/I pass depicted a well-
defined LLCC with a pronounced banding feature over the northeastern
quadrant. The cyclone was being steered on its eastward track by
equatorial westerlies to the south. JTWC never increased the MSW
above 35 kts, and no other warning center assigned tropical storm
status. However, both KGWC and SAB were assigning CI numbers of 2.5,
so minimal tropical storm status seems realistic. By 22/0600 UTC the
eastward motion had resumed with the center located approximately
220 nm north of Brunei. Also, the system had entered PAGASA's AOR and
had been christened Pabling. At 1200 UTC Pabling/29W's center was
located about 110 nm west-southwest of Punta Baja Harbor on Palawan.
Satellite intensity estimates were still 35 kts, but SSM/I data
indicated that the LLCC was decoupled to the east of the deep
convection as the system had encountered increasing vertical shear.
JTWC downgraded Tropical Storm Pabling/29W to a tropical depression
at 23/0600 UTC when it was located about 40 nm west of the southern tip
of Palawan Island. Convection continued to be sheared to the west of
the LLCC and JTWC issued the final warning on the system at 0600 UTC
with the center just off the southern tip of Palawan Island. The MSW
was still estimated at 30 kts, and it is a little unusual for JTWC to
finalize a NWP system until winds have dropped below the normal warning
criteria of 25 kts or else a system has become extratropical. However,
the remnants of Pabling/29W were mentioned in the STWO issued at 0600
UTC on 24 November. Disorganized convection was still associated with
the weak LLCC, but winds by that time were estimated at no higher than
10 to 15 kts.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
As noted above, JTWC was the only agency to classify Pabling/29W as
a tropical storm, and a minimal one at that. Both JMA and PAGASA
carried the system as a 30-kt tropical depression for several days,
which represents good agreement with JTWC's peak 1-min avg MSW estimate
of 35 kts. However, JMA also uses Dvorak T2.5 as the threshold for
tropical storm intensity, so apparently they were not assigning CI
numbers quite as high as some of the other agencies.
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Storm
Pabling/29W have been received.
E. Additional Discussion
------------------------
Mark Lander of the University of Guam posted an interesting
discussion about the circulation features in the Southeast Asia/
Northern Australia region during the time when Pabling/29W was active.
Two monsoon troughs were present--one north of the equator and one to
the south. And as Mark writes, "tropical cyclones are popping out
all over". The westernmost system in each hemisphere--a depression in
the South Indian Ocean (identified by JTWC as TC-04S) and Pabling/29W
were moving eastward, while the easternmost systems--Ondoy/28W and a
depression in the Arafura Sea (briefly identified as TC-03S by JTWC)
were moving westward. Mark points out that the situation was somewhat
reminiscent of late 1996 when several tropical cyclones formed in each
hemisphere along twin monsoon, or near-equatorial, troughs. Tropical
Storm Greg in December of that year moved on a very similar track to
Pabling/29W, moving eastward at a very low latitude and making landfall
in East Malaysia (on Borneo). (NOTE: The term "tropical cyclone" as
used by Mark is to be understood in the generic sense of a system of
any intensity, not in the more restrictive sense in which it is used
in the Southern Hemisphere.)
Addendum to October Summary
---------------------------
A few days after the October summary had been disseminated, I
received an e-mail from Ms. Duong Lien Chau from Hydromet Service
of Vietnam with additional information on the unnamed tropical
depression which affected the country in October. According to
Ms. Duong, the depression made landfall very close to Tuy Hoa (13.1N,
109.3E) with maximum sustained winds of 31 kts, gusting to 35 kts.
The depression brought rainfall amounts of 100-200 mm for the central
part of Vietnam with a few locations netting 200-300 mm. However,
no significant damage was reported due to the storm.
I also received some information on this system from Roger Edson,
who had reviewed some satellite imagery and also QuikScat data for
the depression. Roger noted that the depression was accompanied by
a large monsoon-like cloud mass capable of producing copious amounts
of precipitation. QuikScat showed winds 30-35 kts, which also agreed
with his estimate based on imagery. Roger concluded that the system
could have possibly been a minimal tropical storm.
A special thanks to Ms. Duong and Roger for the information they
provided.
***********************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for November: 1 tropical cyclone of gale intensity
NOTE: The tracking and intensity information for North Indian Ocean
Basin tropical cyclones is based primarily upon operational warnings
from the Joint Typhoon Warning Center of the U. S. Air Force and Navy
(JTWC) at Pearl Harbor, Hawaii. Occasionally some information may
be gleaned from the daily Tropical Weather Outlooks and other bulletins
issued by the Indian Meteorological Department (IMD), which is the
WMO's RSMC for the basin.
The MSW are based on a 1-min averaging period, which is used by
all U. S. civilian and military weather services for tropical cyclone
warnings. For synoptic observations in the North Indian region,
both 10-min and 3-min average winds are employed, but IMD makes no
attempt to modify the Dvorak scale for estimating tropical cyclone
intensity; hence, a 1-min avg MSW is implied. In the North Indian
basin JTWC usually does not initiate warnings until a system is
well-organized and likely to attain tropical storm status within
48 hours.
North Indian Ocean Tropical Activity for November
-------------------------------------------------
Climatologically, November is one of the more active months in the
North Indian Ocean basin, having produced some intense hurricanes in
the past. However, November of 2001 was rather quiet, producing only
one tropical cyclone which very briefly was a minimal tropical storm.
This system was the fourth system in 2001 to be numbered by JTWC, but
was the only one to occur in the Bay of Bengal, which is the half of
the basin that normally sees about 2/3 to 3/4 of the tropical cyclone
activity.
NOTE: Following the narrative for Tropical Cyclone 04B is a very brief
addendum to the October summary.
Tropical Cyclone (TC-04B)
9 - 12 November
--------------------------
An area of convection developed in the southern Bay of Bengal
in early November--on the 7th it was located about 150 nm east of
Madras, India. Deep convection was intermittent, but the broad
cyclonic circulation was located under a ridge axis with favorable
upper-level outflow. A QuikScat pass at 08/1221 UTC indicated a
weak but well-defined LLCC embedded in a broad trough which extended
southwest to northeast. A TRMM pass at 1100 UTC on 9 November
indicated increasing organization of convection near the circulation
center. The MSW was estimated at 20-25 kts and JTWC upgraded the
development potential to fair. JTWC issued a TCFA at 1400 UTC on the
10th when the disturbance was centered roughly 150 nm east-northeast
of Madras. The convection had expanded during the previous 12 hours,
and synoptic data along the Indian coast indicated pressure falls
associated with the offshore LOW. The maximum winds were estimated
at 25-30 kts and the system lay under a ridge axis with minimal shear
and diffluent flow aloft. A QuikScat pass around 1800 UTC indicated
increased organization of the LLCC with the strongest winds located
to the west and southwest of the center.
JTWC issued their first warning on Tropical Cyclone 04B at 0000 UTC
on the 11th. The system was located just off the Orissa coast,
drifting northward at 3 kts. Animated visible imagery indicated an
exposed LLCC situated in a weakness in the subtropical ridge. The
cyclone was forecast to track slowly northward and make landfall in
eastern India. The second warning, issued at 11/1200 UTC, placed
the center of TC-04B approximately 275 nm northeast of Madras, moving
northward at 5 kts. The MSW of 30 kts was based on CI estimates of
30 kts and synoptic data. However, an amended warning was later issued
upgrading the MSW to 35 kts based on a QuikScat pass at 1245 UTC. The
slight intensification trend was brief--at 12/0000 UTC the MSW was
lowered back to 30 kts based on CI estimates of 25 kts and synoptic
data indicating 25-30 kt winds. Animated enhanced infrared imagery
depicted intermittent bursts of deep convection decoupled well to the
north of the poorly-defined LLCC. Recent QuikScat data revealed that
the gale-force winds in the western quadrant were weakening and that
winds in the southern quadrant had dropped to 20 kts. Tropical Cyclone
04B had become a victim of strong southerly shear. The 12/0000 UTC
warning was the final one issued by JTWC and placed the weakening
center about 350 nm northeast of Madras, moving northeastward at 6 kts.
Addendum to October Summary
---------------------------
In the October summary I reported on a Bay of Bengal system for
which JTWC did not issue any warnings, but which India had classified
as a cyclonic storm (i.e., a tropical storm). Roger Edson (at my
request) also sent me his opinion on this system. Roger indicates
that he examined scatterometer data and multi-spectral satellite
imagery, and in his opinion the system never reached a maximum
intensity higher than 25 kts. The center was always well-removed
from the convection.
***********************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for November: 1 tropical depression **
1 tropical cyclone ++
** - treated as a minimal tropical storm by JTWC
++ - system formed east of 90E in the Australian Region
The primary sources of information upon which the narrative is based
are the warnings issued by the TCWC on La Reunion Island, part of Meteo
France, which is the RSMC for the Southwest Indian Ocean basin.
However, cyclones in this region are named by the sub-regional centres
on Mauritius and Madagascar with longitude 55E being the dividing line
between their respective areas. La Reunion only advises these centres
regarding the intensity of tropical systems. References to sustained
winds should be understood as implying a 10-min averaging period unless
otherwise stated. In the accompanying tracks file some position
comparisons have been made with JTWC's positions, and warnings from
JTWC were used as a source of 1-min avg MSW estimates.
Southwest Indian Ocean Tropical Activity for November
-----------------------------------------------------
Two tropical systems roamed Southwest Indian Ocean waters during
November, both in the eastern portion of the basin. A tropical
disturbance, numbered 03 by La Reunion, briefly reached tropical
depression status (10-min mean winds of 30 kts) on 21 November. This
system was treated as a minimal tropical storm by JTWC. The other
tropical system, Tropical Cyclone Bako, formed east of longitude 90E
in the Australian Region where it was originally known as Bessi. The
complete history of Tropical Cyclone Bessi-Bako can be found in the
section of this summary covering the Northwest Australia/Southeast
Indian Ocean region.
Tropical Depression (TC-04S / MFR #3)
15 - 23 November
--------------------------------------
An area of convection developed on 14 November approximately 170 nm
east-northeast of Diego Garcia in association with a developing LLCC.
The convection was disorganized, but a 200-mb analysis indicated that
the disturbance was located within a favorable environment for further
development with low vertical shear and divergence aloft. A QuikScat
pass at 15/1248 UTC was the basis for relocating the disturbance to a
position about 440 nm east of Diego Garcia. Convection near the LLCC
was continuing to cycle in intensity. A special STWO issued by JTWC
at 16/1600 UTC placed the system approximately 300 nm southeast of
Diego Garcia. The potential for development was upgraded to fair--the
convection was persisting and the upper-level environment improving.
Over the next couple of days the disturbance changed little in organ-
ization while meandering about southeast of Diego Garcia. La Reunion
issued sporadic bulletins on the broad and diffuse system beginning
at 1200 UTC on the 15th.
At 19/1800 UTC JTWC relocated the LLCC to a point about 450 nm
east-southeast of Diego Garcia and downgraded the potential for
development to poor. The system was moving south of the upper-level
ridge axis into an area of northerly winds. By 1100 UTC on the 20th
the disturbance had moved farther to the east and was located roughly
600 nm east-southeast of Diego Garcia. The LLCC was located once more
beneath the upper-level ridge axis in an environment of lower shear
and enhanced outflow; therefore, the development potential was
re-upgraded to fair. By 21/0300 UTC the LLCC had migrated to a
position approximately 675 nm east-southeast of Diego Garcia and had
shown a marked improvement in its convective organization. JTWC
issued a TCFA, estimating the winds at 25-30 kts. The first warning
from JTWC on TC-04S was issued at 21/0600 UTC with an initial inten-
sity of 30 kts. At the same time MFR upgraded the disturbance to
tropical depression status with 10-min mean winds estimated at 30 kts.
The depression's center was then located approximately 700 nm east-
southeast of Diego Garcia. Water vapor imagery depicted a large-
amplitude trough approaching from the southwest. Models indicated
that a cut-off LOW would develop near the base of the trough which
should prevent TC-04S from becoming embedded in the northwesterlies
ahead of the trough and moving off to the southeast.
At 1800 UTC the system was centered about 725 nm east-southeast of
Diego Garcia. JTWC upped the 1-min avg MSW to 35 kts based on CI
estimates of 30 and 35 kts. The system was moving southeastward at
4 kts, but a turn to the west was forecast. MFR downgraded the
depression back to tropical disturbance status with 25-kt peak winds
at 22/0600 UTC, although 30-kt winds were forecast to occur in
isolated spots in the southern semicircle. JTWC maintained the 35-kt
MSW at 0600 UTC based on 35-kt winds depicted by a 22/0058 UTC QuikScat
pass. TC-04S was tracking very slowly to the south-southwest at this
time, and by 1800 UTC the forecast turn to the west had occurred, the
system being steered by a low to mid-level subtropical ridge. The
center was estimated to be about 630 nm east-southeast of Diego Garcia
and moving westward at 10 kts. JTWC reported the MSW at 30 kts based
on CI estimates of 25 and 30 kts.
It is interesting to compare how the intensity forecast (as per the
JTWC warnings) evolved on 21 and 22 November. At 21/1800 UTC the
forecast called for no strengthening with dissipation by the end of
the forecast period. The 22/0600 UTC warning, however, forecast
modest strengthening while the 1800 UTC forecast called for slight
weakening initially followed by static intensity through the remainder
of the forecast period. Despite the hints at some strengthening on
the 22nd, the intensity forecast included in the 21/1800 UTC warning
proved to be the one that verified. By 23/0600 UTC the MSW had
dropped to 25 kts and JTWC issued its final warning on TC-04S with the
weakening center located about 560 nm southeast of Diego Garcia. Six
hours later, La Reunion issued its final bulletin on the system.
***********************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for November: 2 tropical LOWs **
1 tropical cyclone ++
** - one system originated east of 135E and was very briefly treated
as a minimal tropical storm by JTWC
++ - system later moved across 90E into the Southwest Indian Ocean
The primary sources of information for Northwest Australia/Southeast
Indian Ocean tropical cyclones are the warnings and bulletins issued by
the TCWC at Perth, Western Australia, and Darwin, Northern Territory.
References to sustained winds should be understood as being based on a
10-minute averaging period unless otherwise noted. Warnings issued by
JTWC in Hawaii were the source of the 1-minute average MSW values given
in the accompanying cyclone tracks file and were occasionally used for
comparison purposes.
Northwest Australia/Southeast Indian Ocean
Tropical Activity for November
------------------------------------------
The Perth TCWC issued warnings on two tropical systems during the
month of November. The first was a tropical LOW early in the month
which moved over waters west of Cocos Island. The initial weak LOW
actually originated just west of longitude 90E about 625 nm west-
northwest of Cocos on 7 November. It moved slowly east-southeastward,
reaching a point 250 nm west of the island early on the 10th. Perth
issued gale warnings on the 10th in anticipation of the LOW's
developing into a tropical cyclone. This did not happen, however, and
the final warning was issued at 10/2200 UTC. The residual LOW drifted
back westward and was last mentioned on 13 November when located about
500 nm west of Cocos Island. JTWC did not issue any warnings on this
system, although a TCFA was issued at 2000 UTC on 9 November.
The other system was Tropical Cyclone Bessi which formed northwest
of Cocos Island late in the month. Bessi moved slowly southward,
later turning westward and crossing longtidue 90E into the Southwest
Indian Ocean basin where it received the name Bako. Since the cyclone
originated in Perth's AOR, it is covered in its entirety below.
One other tropical LOW of note was one which moved from the Papua
New Guinea area westward at a very low latitude, moving into the
Arafura Sea and dissipating near the island of Timor. Darwin never
issued any warnings on the LOW, but JTWC briefly upgraded it to a
minimal tropical storm. Because of this, and because of the unusual
track it followed, I have given it a little more coverage than I
normally would give a weak system. The history of this tropical LOW
is contained in the section of this summary covering the Northeast
Australia/Coral Sea region.
Tropical Cyclone Bessi-Bako (TC-05S / MFR #4)
25 November - 6 December
----------------------------------------------
A. Storm Origins
----------------
A STWO issued by JTWC at 0900 UTC on 25 November noted that an area
of convection had developed approximately 370 nm southwest of Sumatra
and had persisted for over 12 hours. Satellite imagery indicated an
apparent LLCC associated with the convection while a 200-mb analysis
indicated that the disturbance lay in a region of marginal wind shear
with a developing anticyclone aloft. At 1800 UTC the system was
located roughly 450 nm southwest of Sumatra and satellite imagery
indicated increasing coverage of deep convection near the center.
Upper-level conditions were still conducive for further intensifi-
cation so JTWC upgraded the development potential to fair. JTWC
issued a TCFA at 26/0300 UTC, relocating the LLCC to a position about
240 nm north-northwest of Cocos Island. Winds were estimated at 20
to 25 kts and deep convection near the center had continued to become
better organized. The Perth TCWC began issuing gale warnings for
the LOW in anticipation of its strengthening. Some moderate shear
affecting the system retarded its development slightly, making it
necessary for JTWC to issue a second TCFA at 0300 UTC on the 27th.
At 27/0600 UTC Perth upgraded the LOW to Tropical Cyclone Bessi,
located approximately 350 nm northwest of Cocos Island, moving west
at 7 kts. JTWC also issued their first warning on TC-05S at the same
time, estimating the intensity at 30 kts (based on CI estimates of
30 and 35 kts).
B. Track and Intensity History
------------------------------
Bessi's initial westward track gradually curved to the south as a
passing mid-latitude trough weakened the subtropical ridge. The storm
reached an initial peak intensity of 60 kts (10-min avg from Perth)
at 0400 UTC on the 28th when centered approximately 375 nm west-
northwest of Cocos Island, but thereafter began to weaken as it moved
southward into a zone of significant vertical shear. By 29/0300 UTC
Perth had dropped the MSW to 40 kts as Bessi moved south-southeastward
at 8 kts. Satellite imagery revealed a partially-exposed LLCC with
the associated deep convection displaced equatorward from the center.
At 1800 UTC the cyclone was tracking south-southwestward, still in an
environment of moderate shear, but by 0600 UTC on 30 November was
moving west at 13 kts. Satellite intensity estimates were running
around 35 kts, but there was a ship report of 45-kt winds. Tropical
Cyclone Bessi had moved west of longitude 90E by 30/0400 UTC, and at
0600 UTC was renamed Tropical Storm Bako by Mauritius.
By the time the storm had entered the Southwest Indian Ocean basin,
it had moved beneath an upper-level ridge axis into an area of reduced
shear and convection responded by increasing once more. At 1800 UTC
Bessi-Bako was moving west-southwestward at 6 kts, and JTWC had
increased the 1-min avg MSW back to 55 kts. La Reunion soon followed
suit, upping the 10-min avg MSW estimate to 50 kts at 0600 UTC on
1 December and to 60 kts at 1800 UTC. Bako's forward motion had
slowed to only 2 kts, and a SSM/I pass shortly before 0600 UTC had
depicted a 40-nm diameter eye feature. By 02/0600 UTC the storm
was moving south-southwestward at 4 kts. A 40-nm banding eye feature
was visible, and CI estimates had reached 65 kts. JTWC estimated the
1-min avg MSW at 65 kts, and at 1800 UTC increased it to 75 kts--the
peak intensity for the storm. La Reunion also upped the 10-min mean
wind estimate to 65 kts, making Bako officially a tropical cyclone,
(i.e., a hurricane). Tropical Cyclone Bako at 1800 UTC was located
approximately 700 nm west-southwest of Cocos Island and moving south-
southeastward at 6 kts. Satellite imagery revealed a ragged eye 20 nm
in diameter. The storm was located beneath an upper-level ridge with
a poleward outflow channel evident. The south-southeastward motion
was due to the steering influence of a mid-level ridge to the storm's
east and an approaching mid-latitude trough from the west.
By 0600 UTC on 3 December Bako's forward motion had slowed once more
and the cyclone was drifting southward at 2 kts. Animated visible and
infrared satellite imagery depicted a partially-exposed LLCC. The La
Reunion TCWC downgraded Bako to a severe tropical storm with 60-kt
winds at 1200 UTC. By 1800 UTC the storm was moving to the south-
southeast at 5 kts and slowly weakening as it came under the influence
of moderate vertical shear south of the upper-level ridge axis. Bako
had become quasi-stationary by 04/0600 UTC with a fully-exposed LLCC
evident in satellite imagery. MFR and JTWC lowered their intensity
estimates to 40 kts (10-min avg) and 45 kts (1-min avg), respectively.
A 200-mb analysis indicated that the storm was located beneath strong
upper-level westerlies associated with a longwave trough over the South
Indian Ocean. Bako had weakened to minimal tropical storm intensity
by 1800 UTC on the 4th, and was downgraded to a tropical depression
by MFR at 05/0000 UTC. JTWC issued their final warning at 0600 UTC,
downgrading the system to a 30-kt depression located about 750 nm
southwest of Cocos Island and drifting southwestward. La Reunion
declared Bako extratropical at 05/1200 UTC but continued to issue
bulletins for another 24 hours as the LOW continued to move slowly
southward. A few gales were forecast for waters well south of the
center through 06/1200 UTC.
C. Comparisons Between Perth/La Reunion and JTWC
------------------------------------------------
Intensity estimates between JTWC and Perth were in reasonably good
agreement, although the highest MSW estimated by JTWC during Bessi's
initial peak was 55 kts (1-min avg), whereas Perth estimated a 10-min
avg MSW of 60 kts--equivalent to a 1-min avg MSW of about 70 kts.
After Bessi had crossed 90E and become Bako, the respective MSW values
reported by La Reunion and JTWC were in very good agreement--JTWC's
peak 1-min avg MSW of 75 kts being equivalent to MFR's peak 10-min avg
MSW of 65 kts. During the cyclone's decaying phase, the intensities
reported by the two agencies were also in close agreement.
D. Damage and Casualties
------------------------
Since Tropical Cyclone Bessi-Bako remained at sea far from any
populated shores, no reports of damage or casualties have been
received.
***********************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for November: 1 tropical LOW **
1 non-tropical LOW
** - system moved westward across 135E at a very low latitude
The primary sources of information for Northeast Australia/Coral Sea
tropical cyclones are the warnings and bulletins issued by the TCWCs
at Darwin, Northern Territory, and Brisbane, Queensland. References
to sustained winds should be understood as being based on a 10-minute
averaging period unless otherwise noted. Warnings issued by JTWC in
in Hawaii were the source of the 1-minute average MSW values given
in the accompanying cyclone tracks file and were occasionally used for
comparison purposes.
Northeast Australia/Coral Sea
Tropical Activity for November
------------------------------
There were no tropical cyclones in the Northeast Australia/Coral
Sea region during November. Around mid-month a weak tropical LOW
formed near Port Moresby, Papua New Guinea, and moved westward along
the southern coast of the island of New Guinea and into the Arafura
Sea at a rather low latitude. The LOW became better organized in the
Arafura Sea and JTWC briefly upgraded it to a minimal tropical storm.
For this reason and because of its unusual track, I have covered it
in greater detail than I normally do for weak systems. Late in the
month the Brisbane TCWC issued gale warnings in association with a
non-tropical LOW which formed about 250 nm east-northeast of Brisbane
and moved generally eastward into the Fiji AOR. Since this LOW
possibly could have had some hybrid features, I included a track for
it in the November cyclone tracks file.
Tropical LOW (TC-03S)
15 - 24 November
----------------------
The daily TWO issued by Darwin on 15 November mentioned that a weak
1006-mb LOW was located near Port Moresby, Papua New Guinea, and was
forecast to move westward into the Arafura Sea. JTWC issued a STWO at
16/0200 UTC which noted that there had been a rapid increase in
convective activity associated with the LOW, which by then was located
just northeast of the Cape York Peninsula. The LOW was near the axis
of a sub-equatorial ridge under minimal vertical shear and with winds
estimated at 15-20 kts (per JTWC). By the 17th the LOW was situated
over southern Papua New Guinea north of the Torres Strait. Darwin gave
the LOW a moderate chance of developing into a tropical cyclone after
72 hours, and JTWC upgraded the development potential to fair. Early
on 18 November the system was still over southern Papua New Guinea
about 370 nm north-northeast of Nhulunbuy in Australia's Northern
Territory.
By the 19th the LOW was over the Arafura Sea, moving westward.
JTWC's STWO indicated that convection was sheared west of the well-
defined, yet weak, circulation center. The system was beneath the
diffluent flow region of the sub-equatorial ridge--maximum winds were
estimated at 20-25 kts. The LOW continued moving westward on the 20th
about 325 nm north of the Northern Territory coast, still in an
environment of moderate shear. At 1800 UTC, when JTWC issued their
STWO, the center was estimated to be about 350 nm east-northeast of the
Indonesian island of Timor. JTWC issued a TCFA at 21/0000 UTC, placing
the LOW's center approximately 200 nm east-northeast of Timor in the
Banda Sea, or about 360 nm north of Darwin. Convection was increasing
in organization near the LLCC and shear was weak--the maximum winds
were estimated at 25-30 kts. Darwin also gave the LOW a moderate
chance of developing into a cyclone after 48 hours.
Up to this point Darwin and JTWC had been pretty much in agreement
regarding the LOW's strength and its potential for development.
However, that changed later on the 21st. Darwin continued to regard
the system as a tropical LOW without any gale warnings being issued.
(The Australian warning centres normally issue gale warnings for a
tropical LOW which is expected to develop into a tropical cyclone
usually in advance of the actual appearance of gale-force winds.)
JTWC, however, issued a warning at 21/0600 UTC upgrading the LOW to
a 35-kt tropical cyclone (i.e., a tropical storm in U. S. terminology.)
The JTWC warning placed the center in the Banda Sea east of Timor, or
about 350 nm north-northwest of Darwin. The warning intensity was
based on CI estimates of 30 and 45 kts, i.e., Dvorak 2.0 and 3.0.
The warning remarked that visible animated imagery depicted signifi-
cant organization of convection over the vortex center during the past
few hours.
The 21/0600 UTC warning had also forecast a slight strengthening.
This, however, did not materialize. The second and final JTWC warning,
issued at 1800 UTC, reduced the MSW to 25 kts. CI estimates were 25
to 30 kts, but synoptic reports indicated winds in the area of only
15 kts. Satellite animation depicted deep convection but no organized
LLCC, and synoptic reports indicated surface pressures around 1012 mb.
Darwin continued to mention the LOW through the 24th, but gave it only
a low chance of developing into a tropical cyclone.
The tropical LOW described in the above paragraphs was admittedly
rather insignificant. I gave it more detailed coverage than I normally
do for such systems for two reasons: the rarity of its degree of
development in the Arafura and Banda seas at low latitudes, and the
confusion that erupted over the system regarding the matter of nomen-
clature, primarily due to its intensity hovering near that "magical"
man-made threshold of 34 kts. Many students of tropical cyclone clima-
tology would likely not regard the northern reaches of the Arafura Sea
and especially the Banda Sea as locations where tropical cyclones,
especially intense ones, can occur, but there have been quite a few,
albeit rare, destructive tropical cyclones recorded in those areas
over the years. For the Feature of the Month in the upcoming December
summary, I plan to include a listing of destructive Indonesian tropical
cyclones at very low-latitudes which Jeff Callaghan compiled.
Regarding the issue of tropical system nomenclature, this particular
system was just at that intensity level where by following the more
liberal CI estimate or by taking an average, the MSW could be estimated
at 35 kts, i.e., a tropical cyclone in accordance with Australian
terminology; but by adhering to the more conservative CI estimate,
the intensity would fall below gale-force in terms of both 1-min and
10-min averages. Darwin opted for the latter, which meant that
they treated the system as simply a tropical LOW (the Australian TCWCs
do not officially use the term "tropical depression") whereas JTWC
opted to follow the more liberal intensity assessment. In the Dvorak
scale, T2.5 equates to gale-force in the 1-min avg system, but since
a given Dvorak rating implies a range of intensities, and since the
difference between a 1-min avg wind and a 10-min avg wind at the
threshold of gale-force is only about 4 kts, the Japanese Meteoro-
logical Agency equates a solid T2.5 to tropical storm intensity, even
though they use a 10-min avg wind in their warnings. This difference
in intensity assessment, however slight, resulted in confusion when
personnel on a U. S. naval ship related to the crew of an Australian
naval ship that a tropical cyclone was in the vicinity. In Australian
terminology, the term "tropical cyclone" specifically implies 10-min
avg winds exceeding gale force, whereas in U. S. terminology "tropical
cyclone" is a generic term for tropical systems of all intensities.
Furthermore, in the Southwest Indian Ocean basin, the term "tropical
cyclone" implies a system with 10-min avg winds of 64 kts or greater
(i.e., a hurricane). In the author's opinion, of all the differences
in terminology across the various oceanic basins, the multiple meanings
attached to the basic term "tropical cyclone" probably leads to the
most confusion. (See the April, 2001, tropical cyclone summary for a
description of official warning terminologies used by all the major
warning centres.)
***********************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for November: 1 tropical cyclone of gale intensity
Most of the information presented below was taken from operational
warnings and advisories issued by the Fiji TCWC at Nadi. References
to sustained winds should be understood as being based on a 10-minute
averaging period unless otherwise noted. Warnings issued by JTWC/NPMOC
in Hawaii were the source of the 1-minute average MSW values given in
the accompanying cyclone tracks file and were occasionally used for
comparison purposes.
The report on Tropical Cyclone Trina was written by Alipate
Waqaicelua, Chief Forecaster at the Nadi TCWC, with some additional
information added by myself. A very special thanks to Alipate for
preparing and sending the report to me (as well as the track for
the cyclone.)
South Pacific Tropical Activity for November
--------------------------------------------
Last season the first South Pacific tropical cyclone did not make
its appearance until February. In contrast, the current season got
underway quite early with the development of Tropical Cyclone Trina
near Rarotonga in late November. Trina remained weak, but did cause
some significant damage on the island of Mangaia, mainly from flooding.
Tropical Cyclone Trina (TC-06P / TD-01F)
29 November - 3 December
-----------------------------------------
A. Storm Origins
----------------
Trina was the first tropical cyclone of the 2001-2002 tropical
cyclone season in RSMC Nadi's AOR. It was first identified as a
sheared hybrid, developing off an upper-level cut-off LOW which
eventually spun its way to the surface to the west of Rarotonga on
28 and 29 November. The system was then slow-moving. At 29/1800 UTC,
Tropical Depression 01F was located only about 25 nm southwest of
Rarotonga over marginally warm SSTs of around 27 C and under strong
shear. By 30/0000 UTC it had drifted closer to Rarotonga with deep
convection still displaced to between 30 and 120 nm southeast of the
exposed LLCC. However, around 30/0230 UTC deep-layered convection was
increasing in curvature and tops were steadily cooling. With an
intense surface anticyclone to the south significantly enhancing the
gradient in the southwest quadrant, TD-01F was then named Tropical
Cyclone Trina at 30/0700 UTC when located about 45 nm south-southeast
of Rarotonga.
B. Track and Intensity History
------------------------------
After being named, the exposed LLCC drifted under the upper-level
trough axis and into a weak steering regime. By December 01/0600 UTC,
the LLCC had partly slipped under the deep convection. However,
prevailing shear prevented any opportunities for intensification.
Therefore, for its entire life as a tropical cyclone, Trina maintained
gale intensity. Trina drifted slowly eastward on 30 November and
1 December. At 0000 UTC on 2 December the cyclone was downgraded to
tropical depression status when located about 40 nm northwest of
Mangaia. The depression lingered in the area for another day or
two and still produced a few gales in a boundary at some distance
southwest of the center.
The Southern Cooks, especially Rarotonga and Mangaia, were put under
a Tropical Cyclone Alert in the first Special Weather Bulletin (SWB)
(updated every 6 hours) issued at 0809 UTC on 30 November. Twelve
hours later, Rarotonga was placed under a Gale Warning while Mangaia
was still under Alert. At 0200 UTC on 1 December, Mangaia was placed
under a Gale Warning as the cyclone drifted closer to the island. Six
hours later, only Mangaia was under a Gale Warning. The final SWB for
Mangaia was issued around 03/0335 UTC, after Trina had been downgraded
to a tropical depression.
C. Comparisons Between Nadi and NPMOC
-------------------------------------
NPMOC issued only three warnings for Tropical Cyclone Trina. The
first one, issued at 1200 UTC on 30 November, reported a 1-min avg
MSW of 35 kts. Fiji at this time was also reporting 35 kts for their
10-min avg MSW estimate. The remaining two NPMOC warnings estimated
the intensity at 30 kts while Fiji still reported 35 kts, so the fore-
casters at Nadi apparently saw Trina as a slightly stronger system
than did NPMOC.
D. Damage and Casualties
------------------------
Unconfirmed damage assessments reported that Mangaia sustained
inland and coastal flooding and erosion with 80% of root crops in one
area totally destroyed and about 20% of the livestock lost. In Raro-
tonga, especially over the southeastern side of the island, some
minimal damage was incurred from wind and surge. The December mango
crop was destroyed. A lady was very fortunate when a coconut tree
snapped and landed on her van as she was driving along the main road.
The van consequently tipped over on the side.
The above information came from Alipate's report. I located some
additional information on the website of the ReliefWeb. Four days of
heavy rains on Mangaia resulted in the worst flooding on the island
in 50 years. Parts of the island were under 2 metres of water. Some
of the press releases indicated that winds gusted above hurricane
force--somewhat strong for a minimal tropical cyclone but certainly
possible in strong thunderstorms. About 90% of the taro crop was
inundated and lost while other fruit crops fared badly also. The
latter press releases indicated that about 60% of the livestock on
Mangaia--pigs, goats, chickens and horses--were drowned. Fortunately,
no human lives were apparently lost.
***********************************************************************
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
November as an example: nov01.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: nov01.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.ph> OR http://66.40.4.61>
http://www.hurricanealley.net/>
http://www.qisfl.net/home/hurricanemike>
http://www.met.fsu.edu/gsc/Docs/Grads/henning/cyclones/>
NOTE: The URL for Michael V. Padua's Typhoon 2000 website has
changed.
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
JTWC now has available on its website the complete Annual Tropical
Cyclone Report (ATCR) for 2001 (2000-2001 season for the Southern
Hemisphere). 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 2001 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 2001
Atlantic and Eastern North Pacific cyclones are now available, as
well as track charts and reports on storms from earlier years.
The URL is: http://www.nhc.noaa.gov>
A special thanks to Michael Bath of Wollongbar, New South Wales,
Australia, for assisting me with proofreading the summaries.
Prepared by: Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays)
***********************************************************************
***********************************************************************
|
Document: summ0111.htm
Updated: 27th December 2006 |
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