Tropical Cyclones [Index]

Monthly Global Tropical Cyclone Summary April 1998 [Summaries and Track Data] [Prepared by Gary Padgett]

                 MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY

                               APRIL, 1998

  (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.)


  SPECIAL NOTE to users of the TRACK FILES:

     I am going to make a slight change in the manner in which I handle
  intermonthly cyclones in order to minimize the number of track files
  that cover only a portion of a cyclone's life span.  For cyclones
  forming late in a given calendar month and that do not cause any
  significant effects in the month of formation, the narrative will
  contain a reference to the system but the track file will be contained
  in the summary for the concluding month.   For storms which carry over
  into the new month for only a few days and (especially) for which I
  have the complete tracking information already in hand when I prepare
  the summary for the previous month, I shall include the track file in
  the summary for the month of formation (e.g., Tropical Cyclone Bart).

     Cyclones whose history is split fairly evenly between two months and
  which are either intense or else cause significant effects in the month
  of formation I'll treat as I have previously done--ending the track
  abruptly at 0000 UTC on the first day of the second month and picking
  up the narrative at that point in the concluding month's summary.
  However, in these cases (as in previous summaries) the track file in
  the second month's summary will cover the entire history of the
  cyclone.

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        EXTRA FEATURE:  NORTHERN HEMISPHERE CYCLONE NAMES for 1998

     The official Eastern North Pacific hurricane season will begin on
  15 May, and the Atlantic and Central North Pacific official seasons
  begin on 1 June.   The tropical cyclone season in the Western North
  Pacific basin is more or less a year-round affair, but no storms have
  been named so far this year, which is a little unusual.

     Following are the 1998 names for tropical cyclones forming in these
  basins:

  Atlantic - Alex, Bonnie, Charley, Danielle, Earl, Frances, Georges,
       Hermine, Ivan, Jeanne, Karl, Lisa, Mitch, Nicole, Otto, Paula,
       Richard, Shary, Tomas, Virginie, Walter

  Eastern North Pacific - Agatha, Blas, Celia, Darby, Estelle, Frank,
       Georgette, Howard, Isis, Javier, Kay, Lester, Madeline, Newton,
       Orlene, Paine, Roslyn, Seymour, Tina, Virgil, Winifred, Xavier,
       Yolanda, Zeke

  Central North Pacific - Upana, Wene, Alika, Ele, Huko, Ioke, Kika, Lana

  Western North Pacific - Nichole, Otto, Penny, Rex, Stella, Todd, Vicki,
       Waldo, Yanni, Zeb, Alex, Babs, Chip, Dawn, Elvis, Faith, Gil, 
       Hilda, Iris, Jacob, Kate, Leo, Maggie, Neil, Olga, Paul, Rachel,
       Sam, Tanya, Virgil, Wendy, York, Zia, Ann, Bart, Cam, Dan, Eve,
       Frankie, Gloria

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            ADDITIONAL INFORMATION for March Cyclone Summary

     When preparing the March summary I inadvertently overlooked some
  information I'd saved on a tropical LOW in the Gulf of Carpentaria in
  early March.  I was able to gather some more information on this LOW
  from Sam Cleland of the Darwin TCWC.   (Thanks to Sam for passing along
  the additional data.)

     This LOW appeared to be a surface reflection of the residual mid-
  level center of Tropical Cyclone May in late February.  May had made
  landfall in the southern Gulf of Carpentaria region on 26 Feb and the
  remnants persisted over land for a few days.   Shear separated the
  lower-level circulation from the mid- and upper-level portion of the
  circulation.  The weak surface LOW that broke away dissipated
  rapidly, but the mid-level circulation spun down to the surface and
  a new LOW formed.   JTWC issued a formation alert on this LOW but
  no warnings were subsequently issued.

     Darwin TCWC did issue some gale warnings on this system between
  2300 UTC on 2 Mar and 0000 UTC on 4 Mar.  The LOW remained quasi-
  stationary during this time in the general vicinity of 16.5S, 139E
  in the extreme south-central Gulf of Carpentaria.   The LOW was
  forecast to cause monsoon gales of 30 to 40 kts in the eastern semi-
  circle and central pressure was initially estimated at 998 mb.  By
  04/0000 UTC winds had abated and the final advice was issued.  No
  track is given for this system in the accompanying cyclone track file.

  ***********************************************************************


                            APRIL HIGHLIGHTS

  --> Vanuatu suffers significant cyclone damage early in month
  --> French Polynesia once again experiences cyclone damage

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                           ACTIVITY BY BASINS

  ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico

  Activity for April:  1 possible subtropical storm


              A Possible Subtropical Storm -- Early April
              -------------------------------------------

     At 1400 UTC on 2 Apr the Tropical Prediction Center/National
  Hurricane Center in Miami, FL, issued a Special Tropical Disturbance
  Statement on a non-tropical area of low pressure located in the western
  Atlantic Ocean about 700 nm northeast of Puerto Rico.  This system had
  been moving slowly northward for a couple of days, and had developed
  some organized central convection and was producing gale-force winds
  of 35-45 kts.

     The statement mentioned that although the LOW had taken on some 
  tropical characteristics, it was still somewhat disorganized.  It was 
  forecast to begin moving to the northeast and become absorbed by a 
  cold front over the next few days.    By 0700 UTC on 3 Apr the LOW had 
  moved northward to a position about 525 nm southeast of Bermuda, and 
  the Tropical Weather Discussion issued at that time indicated that the 
  gale center was weakening and there was little convection near the 
  center.   According to Dr. Jack Beven of TPC/TAFB, data on this system
  will be reviewed later to see if the system qualifies as a subtropical 
  cyclone.

  HISTORICAL SIDELIGHT:  Out-of-season tropical cyclones are very rare
  in the Atlantic basin, but a few have occurred; and the general region
  to the northeast of the Puerto Rico area and southeast of Bermuda could
  be considered a "hot spot" of sorts for the formation of tropical and
  subtropical cyclones between December and May.   Some systems forming
  in this general vicinity during the off-season months include:

  (1) A hurricane in March, 1908--struck the Leeward Islands
  (2) Hurricane Able in May, 1951--brushed the northern Bahamas and 
      east coast of Florida
  (3) An unnamed tropical storm in Dec, 1953
  (4) Hurricane Alice in Dec, 1954-Jan, 1955--struck the Leeward Islands
  (5) A subtropical storm in Jan, 1978
  (6) Hurricane Lili in Dec, 1984--briefly threatened the Leeward Islands
  (7) A subtropical storm in Apr, 1992 

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  NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180

  Activity for April:  No tropical cyclones

  ***********************************************************************

  NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180

  Activity for April:  No tropical cyclones

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  NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea

  Activity for April:  No tropical cyclones

  ***********************************************************************

  SOUTH INDIAN OCEAN (SIO) - South Indian Ocean West of Longitude 90E

  Activity for April: 1 tropical depression
                      1 tropical cyclone of gale intensity
                      1 tropical cyclone of hurricane intensity
                         
  NOTE:  The only sources of information on South Indian cyclones I have
  available for the time being are the warnings issued by JTWC.   All the
  winds reported in the narrative are 1-min average maximum sustained
  winds.


               Tropical Cyclone Gemma (TC-32S)   7-15 April
               --------------------------------------------

      The Joint Typhoon Warning Center (JTWC) on Guam issued the first
  warning on a developing tropical depression at 0000 UTC on 7 Apr with
  the circulation centered about 400 nm south-southwest of Diego Garcia.
  Maximum sustained winds were estimated at 30 kts.   At the same time
  the first warning was issued on another depression (TC-33S) located
  about 300 nm to the east-southeast.   TC-32S moved very slowly east-
  northeastward while TC-33S moved northwestward.   By 07/1200 UTC the
  two depressions had merged, resulting in a broad and weak wind field.

     Following this merger TC-32S began to steadily intensify as it
  drifted westward.  By 0000 UTC on 9 Apr the cyclone had been christened
  Gemma by the Mauritius Meteorological Service and was located about
  400 nm southwest of Diego Garcia.  Winds had increased to 55 kts and
  the system halted its westward motion and began to move on an east-
  southeasterly course.  Gemma reached peak intensity at 11/0000 UTC when
  winds were estimated to have reached 70 kts; however, the cyclone began
  to weaken after this point as it moved slowly to the east-northeast.
  An amended warning at 11/0600 UTC, issued after visible imagery had
  become available, indicated that shear had begun to separate the
  upper-level convection from the low-level center.

     Microwave imager data on 12 Apr indicated that the low-level
  features remained well-defined and tightly wrapped in spite of the
  shear.  By 0000 UTC on 13 Apr the weakening Gemma was located about
  550 nm southeast of Diego Garcia with winds down to 45 kts.    The
  cyclone then began moving westward once more as it continued to weaken.
  By 14/1200 UTC the low-level circulation center had become completely
  separated from the convection, but satellite imagery indicated that
  gale-force winds were still possibly occurring to the south and east
  of the center.  The last JTWC warning at 0000 UTC on 15 Apr placed the
  center of the weakening depression about 450 nm south-southeast of
  Diego Garcia and only about 230 nm east of its point of origin.


                    Tropical Cyclone 33S   7 April
                    ------------------------------

     The first warning on TC-33S, issued by JTWC at 0000 UTC on 7 Apr,
  located the system about 600 nm south-southeast of Diego Garcia and
  about 300 nm east-southeast of another developing depression: TC-32S.
  TC-33S moved generally on a northwesterly course while TC-32S drifted
  eastward.   By 07/1200 UTC the estimated center of TC-33S was only
  about 140 nm east-southeast of TC-32S and the two depressions were
  merging into one system which was subsequently referred to as TC-32S.
  Maximum sustained winds in TC-33S were estimated at 30 kts.


                  Tropical Cyclone 34S   19-22 April
                  ----------------------------------

     TC-34S was a relatively weak cyclone that never exceeded gale
  intensity.    It was considered only a depression by the Southwest
  Indian meteorological services and never named.  The first JTWC warning
  placed the system about 225 nm southeast of Diego Garcia at 0000 UTC
  on 19 April with 40-kt winds.  The cyclone was expected to increase
  to hurricane force but persistent vertical shear prevented this from
  occurring.  TC-34S moved generally on a westerly course throughout
  its life.  Maximum sustained winds of 40 kts were estimated to have
  occurred on 19 and 20 April.

     A scatterometer pass at 21/0647 UTC indicated a lessening in the
  organization and in the radial extent of the surface wind field, and
  microwave imager data at 0000 UTC on 22 Apr indicated that the low-
  level circulation center was becoming elongated and the system was
  weakening.  The last warning at 22/1200 UTC downgraded the cyclone
  to a depression about 200 nm east-southeast of Agalega in the western
  South Indian Ocean.
  
  ***********************************************************************

  AUSTRALIAN REGION (AUS) - From Longitude 90E Eastward to Longitude 160E

  Activity for April: 1 tropical depression **

  ** - One warning was issued by JTWC classifying this tropical LOW as
       minimal tropical cyclone with 35-kt winds (1-min average)

  NOTE:  Some of the material presented on Tropical Cyclone 35S is
  taken from the April Darwin Tropical Diagnostic Statement.   Thanks
  to Lori Chappel for sending that report to me.   Unless stated other-
  wise, references to sustained winds imply a 10-min averaging period.


                      Tropical LOW (TC-35S)   19 April
                      --------------------------------

     TC-35S was a short-lived system along the North Kimberley coast of
  Western Australia.    A LOW developed in the eastern Arafura Sea on
  16 Apr as an easterly surge across Australia induced vorticity in the
  weak monsoon trough.  An easterly wave may have also contributed to
  enhanced convection and low-level development.  The LOW moved westward
  through the Arafura Sea and into the Timor Sea.  On the 18th the LOW
  took a more southwesterly or south-southwesterly track.  There was
  little convection near the center with some rainbands displaying
  slightly more organization than the day before.  Locating the center
  was made difficult by various mesoscale vortices springing up within
  the larger circulation.

     During the night of 18 Apr a huge area of convection developed south
  of the estimated surface position.  Organization had increased rapidly
  by 1800 UTC with good outflow channels displayed in the cirrus. Ship
  reports, however, supported locating the surface center much farther
  north.   At 0000 UTC on 19 Apr JTWC issued the first warning on the
  system, locating it near the Western Australian coast about 300 nm
  northeast of Broome.     Coincident with the convection mentioned
  previously Troughton Island (WMO 94102) reported a one hour period of
  gale-force winds reaching a peak sustained wind of 48 kts.  This was
  believed to have been due to convergence in the rain band.    Also,
  a bulletin from the Darwin TCWC at 19/0730 UTC indicated that wind
  gusts to 50 kts were being reported in rain squalls.
  
     Early morning visible images revealed the LOW was farther south
  and was experiencing some shearing.   The low-level center could have
  been translated under the influence of the overnight convection, or
  there could have been two centers with the southernmost one becoming
  predominant.  During the 19th the LOW continued to move farther south 
  and inland and therefore did not strengthen further.    

  ***********************************************************************

  SOUTHWEST PACIFIC (SWP) - South Pacific Ocean East of Longitude 160E

  Activity for April:  2 tropical cyclones of gale intensity
                       1 tropical cyclone of hurricane intensity

  NOTE:  Thanks to Steve Ready of the New Zealand Meteorological Service
  at Wellington for passing along some information on Tropical Cyclone
  Zuman. Unless stated otherwise,  references to sustained winds imply a
  10-min averaging period.


             Tropical Cyclone Zuman (TC-31P)   29 March-6 April
             --------------------------------------------------

     As the month of April opened Tropical Cyclone Zuman had just crossed
  over the northern end of the island of Espiritu Santo, the northernmost
  island of Vanuatu.  At 0000 UTC on 1 Apr the cyclone was centered about
  175 nm north-northwest of Port Vila with maximum sustained winds 
  estimated at 80 kts.   Zuman may have weakened slightly after crossing
  the island but soon recovered from the effects of having been over
  land.  Winds remained near 80 kts through 03/0000 UTC as the cyclone 
  moved on a fairly slow track to the west.   The westward motion halted
  about this time with the storm centered about 450 nm north-northwest of
  Noumea, New Caledonia.    Minimum central pressure in the cyclone's
  history was estimated at 955 mb.

     Zuman then drifted to the south, and then began to slowly accelerate
  in a southeasterly direction while slowly weakening due to increasing
  shear.  The cyclone brushed the entire eastern coast of New Caledonia, 
  passing between that island and the Loyalty Islands on the 5th.
  Reports from ship ELH25 were useful in helping to locate the low-level
  circulation center late on 5 April.    The center of Zuman passed a
  little less than 100 nm east of Noumea at 1800 UTC on the 5th.  Winds
  had decreased to about 40 kts by this time and the last warning from 
  Fiji, downgrading Zuman to a depression, was issued just 6 hrs later.

     The remains of the original vortex induced a depression along a
  cloudband (referred to by Steve Ready as a "son or daughter" of Zuman)
  which was tracked as an extension of Zuman.   This secondary system
  produced several short bursts of heavy rain in the far northern and
  northeastern parts of New Zealand's North Island before slipping away
  toward the Chatham Islands and eventually into the higher latitudes
  of the South Pacific Ocean.  This phase of the cyclone did not produce
  any winds of consequence.
     
     The island of Espiritu Santo sustained heavy damage due to Zuman
  with the eastern and northeastern parts of the island affected most
  severely.  The most serious damage was to dwellings and coconut trees,
  seriously affecting the island's major industry, copra.   All semi-
  permanent houses in Hog Harbour were partly or completely destroyed.
  Other towns hard hit were Port Olry and Luganville.   Fortunately,
  no reports of fatalities have been received as of the time of this
  writing.  If more information on Zuman's effects becomes available
  later it will be included in next month's summary.


              Tropical Cyclone Alan (TC-36P)   19-26 April
              --------------------------------------------

     Tropical Cyclone Alan was yet another in the parade of tropical
  cyclones which have formed well to the east of the dateline in this
  strong El Nino season.  A tropical disturbance had been tracked since
  17/1800 UTC east of the Northern Cooks, and the Fiji Tropical Cyclone
  Warning Centre at Nadi issued the first bulletin on a new depression 
  at 0600 UTC on 19 Apr with the weak center placed about 300 nm 
  southeast of Manihiki Atoll in the Northern Cooks.  The depression 
  organized very slowly over the next several days while remaining 
  in the same general area.  When the advisory upgrading the system 
  to Tropical Cyclone Alan was issued at 1800 UTC on 21 Apr, the center 
  was located somewhat to the north of its original location, being 
  about 150 nm east-southeast of Manihiki.
  
     Alan remained a weak, minimal tropical cyclone and meandered about
  slowly in the same area for a couple of days.   Fiji downgraded Alan
  to a tropical depression at 1200 UTC on 23 Apr.  The center was then
  only about 80 nm south of the location where it had been when it was
  named.   The Naval Pacific Meteorological and Oceanographic Center
  (NPMOC) at Pearl Harbor issued one more warning at 1800 UTC and then
  dropped the system.

     Over the next 24 hrs the system appeared to become better organized
  and warnings were resumed on the 24th--at 1200 UTC by NPMOC and at
  2100 UTC by Nadi.  Alan had by this time begun to move at an increased
  pace to the east-southeast and was located about 300 nm west-northwest
  of Tahiti at 24/2100 UTC.  Of the previous cyclones in this area during
  the current season,  Alan's track most closely matched that of Tropical
  Cyclone Osea back in November.    Alan moved very near or over the
  Society Islands of Maupiti, Bora-Bora, and Raiatea--islands which were
  heavily damaged by TC Osea.   Maximum winds during this stage of Alan
  were estimated at 40 kts.

     The advisory at 1200 UTC on 25 Apr placed Alan about 125 nm west of
  Tahiti, but six hours later, after visible imagery was received, the
  center was re-located about 135 nm northwest of the 25/1200 UTC
  position. The 1800 UTC advisory also downgraded Alan back to a tropical
  depression.  The weakening system continued to drift generally to the
  east-southeast, with the last advisory (at 26/1800 UTC) locating the
  system about 100 nm west-northwest of Tahiti.   The remnants of the
  former cyclone remained in the area west of Tahiti for several days.

     Although weak and diffuse, Alan was not without casualties.  The
  author has received reports of 8 fatalities caused by the storm, mostly
  due to mudslides caused by the attendant torrential rains.  One report
  mentioned 6 deaths on the island of Tahaa which had winds gusting to
  50 kts.  (I have been unable to locate this island on a map, but
  presumably it is in the vicinity of the other islands mentioned above.)
  If any more information on the effects of TC Alan becomes available,
  it will be reported in the next summary.

  NOTE:  This cyclone was accidentally numbered as TC-32P by NPMOC when
  the first warning was issued.  In order to avoid confusion this number
  was used operationally thoughout the cyclone's life, but it will be
  officially listed as TC-36P for historical purposes.  (Thanks to Maj
  Roger Edson, USAF, of JTWC for this tidbit of information.)


              Tropical Cyclone Bart (TC-37P)   28 April-3 May
              -----------------------------------------------

     Tropical Cyclone Bart developed farther east than any previous
  cyclone in this long and active South Pacific season, although it did
  not move as far east or south as did Ursula back in February.   The
  Tropical Disturbance Summary issued by Nadi at 0600 UTC on 26 Apr
  mentioned a tropical disturbance at 17S, 137W.   Another Summary at
  1800 UTC on 28 Apr mentioned one near 15S, 144W.  This was the system
  which developed into Bart.  It is not clear to the author if this was
  a new disturbance or if the earlier disturbance had migrated several
  hundred miles westward.   The developing cyclone was part of a very
  large area of lower-than-normal pressure which contained the remnants
  of Alan.

     The first depression bulletin (at 2200 UTC on 28 Apr) placed the
  center about 350 nm east-northeast of Tahiti.    This position is in
  the midst of the Tuamotu Islands.     Around 1200 UTC on the 29th
  stations in the vicinity were reporting 2 to 3 mb pressure falls with
  strong winds.  Hau (WMO 91944) reported east winds of 25 kts at
  29/1200 UTC.  By 1800 UTC Hau was reporting southeast winds of 35 kts
  with the pressure having fallen 5 mb more.  Tropical Cyclone Bart was
  named at this time and was centered about 575 nm east of Tahiti near
  the island of Hau.

     Bart initially began moving at a fairly good clip to the south and
  south-southeast, but a blocking ridge strengthened on the 30th to the
  south and caused the cyclone's motion to slow down.    Bart's winds
  peaked at 45 kts on 30 Apr and began to weaken steadily on 1 May.
  Satellite imagery around 01/0000 UTC showed that the main convective
  area had been sheared about 60 nm to the southeast of the exposed
  low-level center.

     The system was downgraded to a depression at 0600 UTC on the 1st but
  some gales were still forecast to occur in the southern semi-circle.
  After 01/1200 UTC Bart began to accelerate again in more of an east-
  southeasterly direction. The last bulletin found the weakening system 
  about 50 nm north of Pitcairn Island around 0000 UTC on 3 May.

     The author has received one report of up to 10 fatalities caused by
  Tropical Cyclone Bart, but it is unclear exactly on which island(s)
  these occurred.  Hopefully, more information will be forthcoming, and
  if so, it will be reported in the summary for May.
  
  ***********************************************************************

  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) The files will be named with an obvious nomenclature--using
           April as an example:   apr98.tracks

    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 April summary is the seventh cyclone summary in this series;
  the first one covering the month of October, 1997.  If anyone did
  not receive any of the previous summaries, they may be downloaded
  from the aforementioned FTP site at HRD.   The summary files are
  catalogued with the nomenclature:  oct97.sum, for example.

    Back issues can also be obtained from the following website
  (courtesy of Michael Bath):

    http://australiansevereweather.com/cyclones/>

    The preliminary storm reports for all the 1997 Atlantic and Eastern
  North Pacific tropical cyclones are available on the Tropical
  Prediction Center's website:  http://www.nhc.noaa.gov> .  These
  reports include the analyzed best-track for each cyclone.  The staff
  of JTWC is also working on an on-line version of their Annual Tropical
  Cyclone Report for 1997.  It is still under construction, but the
  best-track files are already available for 1997 Northwestern Pacific
  and North Indian Ocean cyclones.  The URL is:

       http://www.npmocw.navy.mil/npmocw/prods/jtwc.html>

  Prepared by: Gary Padgett
  E-mail:  [email protected]
  Phone:  334-222-5327

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