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


                               JULY, 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.)


                             JULY HIGHLIGHTS

  --> Northwest Pacific season finally gets underway, but barely
  --> First Atlantic tropical storm of the year develops
  --> Northeast Pacific basin activity continues


                              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 have included a Glossary
  of Abbreviations and Acronyms following the Author's Note at the end
  of the summary.


                           ACTIVITY BY BASINS

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

  Activity for July:  1 tropical storm

  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.

                       Tropical Storm Alex  (TC #1)
                           27 July - 2 August

     The season's first tropical storm (and depression) in the Atlantic
  basin developed from a strong tropical wave which left the African
  coast on 25 July.  By late on the 26th the well-organized wave was
  south of the Cape Verde Islands moving west at about 13 kts.  The first
  tropical depression advisory was issued by TPC/NHC at 1200 UTC on 27
  Jul when the system was located about 250 nm south-southwest of the
  Cape Verdes.  Ship reports, satellite imagery, and scatterometer winds
  all indicated a well-defined surface circulation.   Initially the
  depression was still involved with the monsoonal flow and did not
  intensify very rapidly.   Increasing convective organization was seen
  on 28 Jul and the system was upgraded to Tropical Storm Alex at 0000
  UTC on 29 Jul.

     Alex intensified very slowly as it moved westward at a fairly good
  clip.  At 29/1800 UTC a Naval Oceanographic Office drifting buoy
  located about 100 nm west-northwest of the center reported a 6-min avg
  wind of 31 kts and a pressure of 1013 mb.      Alex appeared better
  organized on 30 Jul and winds were increased to 45 kts.   Satellite
  imagery revealed a central area of intense convection with fairly
  symmetric outflow, although there was some south-southwesterly shear
  over the system.

     The storm's forward motion slowed somewhat on 31 Jul as the system
  began to encounter increasing shear.   Convection would intermittently
  cover the center, but most of the time the center was exposed.  Winds
  were decreased to minimal tropical storm strength of 35 kts at 1800
  UTC on 31 Jul but were bumped back up to 45 kts twenty-four hours later
  after a reconnaissance flight on 1 Aug estimated surface winds of 45
  kts with a central pressure of 1010 mb and ship FNPH reported gusts to
  near hurricane force north of the center.

     As Alex weakened it turned a bit more to the west-northwest.  A
  reconnaissance flight early on 2 Aug found only 24-kt winds near the
  center but measured winds of 37 kts in a band 120 nm northeast of the
  storm's center.   However, a later flight could not locate a definite
  surface circulation center so Alex was downgraded to a tropical
  disturbance at 2100 UTC on 2 Aug about 400 nm east-northeast of San
  Juan, Puerto Rico.  The remnants of Alex persisted for a few days but
  never showed any significant signs of re-developing.   Since Alex
  remained far from any populated areas, no deaths or damages are known
  to have resulted from this tropical cyclone.

     Tropical Storm Alex got the Atlantic tropical cyclone season off to
  a later start than average, but not unusally so.    The last year in
  which the first named storm formed later than Alex was 1992, and that
  storm was the very destructive Hurricane Andrew.  (Coincidentally, Alex
  is the replacement name for Andrew in the 6-year rotating list of
  Atlantic tropical cyclone names.)     In each of the seasons from
  1993-1997 the first named storm has made its appearance on or before
  1 July.


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

  Activity for July:  1 tropical storm
                      2 hurricanes

  NOTE:  Much of the information presented below was obtained from the
  TPC/NHC discussion bulletins issued with every regular advisory (CPHC
  for locations west of 140W.)  All references to sustained winds imply
  a 1-min averaging period unless otherwise noted.

                      Tropical Storm Celia  (TC-04E)
                             17 - 21 July

     The Northeast Pacific's third tropical storm of the season developed
  from a large area of disturbed weather which passed just offshore of
  the southwestern Mexican coast on 16 July.   This disturbance produced
  some locally heavy rains over adjacent coastal areas, but the author
  has not learned of any casualties or significant damage due to any
  flooding induced by the heavy rains.  Early on 17 Jul the system began
  to develop rather rapidly. The first advisory issued by TPC/NHC at 1500
  UTC directly upgraded the disturbance to Tropical Storm Celia based on
  a 45-kt wind report from ship KGTI.  The low-level center was easily
  observed by the radar at Cuyutlan, Mexico.   Celia at this time was
  located about 150 nm west-southwest of Manzanillo.

     MSW in Celia were further increased to 50 kts at 0300 UTC on 18 Jul
  based on a 17/1700 UTC report of 50-kt winds from ship 4XGX which was
  located about 90 nm northeast of the center.   The discussion mentioned
  that Dvorak estimates were only 35 kts.  Celia at this time was not
  very well-organized.      The storm initially moved on a northwesterly
  trajectory but began to curve to a more west-northwesterly course as
  it passed south of the tip of Baja California.

     The center of the storm was observed by the Los Cabos radar as Celia
  passed about 120 nm south of Cabo San Lucas shortly after 0600 UTC on
  18 Jul at its peak intensity of 50 kts and estimated central pressure
  of 1000 mb.   The center of the circulation was embedded in a small
  but concentrated area of deep convection.   Based on a cumulative wind
  distribution graphic on TPC/NHC's website, it is likely that gale-force
  winds occurred just offshore from the tip of the Baja peninsula.

     After passing south of Baja California Celia began to slowly weaken
  as it continued on a westerly track out into the Pacific.  Cooler SSTs
  took their toll on the storm, although the weakening was slow to occur
  since the circulation had become quite well-organized.  The storm was
  downgraded to a dissipating depression at 20/0600 UTC, and the final
  advisory was issued at 0000 UTC on 21 Jul with the center located about
  600 nm west of Cabo San Lucas.

                        Hurricane Darby  (TC-05E)
                           23 July - 1 August

     The first advisory on a newly developing tropical cyclone was issued
  by TPC/NHC at 0600 UTC on 23 Jul with the depression centered about
  625 nm south-southwest of Cabo San Lucas.  Tropical Storm Darby was
  christened 12 hrs later with 40-kt winds.   Throughout its life Darby
  moved on a fairly smooth west-northwesterly course which ultimately
  took it well to the north of the Hawaiian Islands.   Hints of an eye
  began to appear early on 24 Jul and by afternoon a well-defined eye
  was noted in satellite imagery.  Darby was upgraded to a hurricane
  at 24/1200 UTC when located about 650 nm southwest of Cabo San Lucas.

     Hurricane Darby intensified quite rapidly, reaching an estimated
  peak intensity of 105 kts by 25/0600 UTC.     Minimum pressure was
  estimated to have been 960 mb.  The hurricane weakened slightly early
  on 26 Jul, but by mid-day a large eye had reappeared.    Darby had
  apparently been undergoing a concentric eyewall replacement cycle.
  As Darby continued moving farther to the west, its track paralleled
  the 25 deg C isotherm so the storm did not weaken as quickly as
  forecast--MSW remained at 100 kts through 28/0000 UTC.

     The hurricane crossed 140W and entered the Honolulu AOR around
  0600 UTC on 29 Jul.  Darby was a minimal hurricane by this time and
  was downgraded to a tropical storm on the next advisory from CPHC.
  The combination of cooler SSTs and increased vertical shear caused
  Darby to steadily weaken as it continued on its west-northwesterly
  track which carried it well to the north of Hawaii.   The system was
  downgraded to a depression at 0600 UTC on 31 July about 350 nm north-
  east of Hilo, and the final advisory was issued at 0000 UTC on 1 Aug
  with the weak center about 250 nm north-northeast of Hilo.  A weak
  residual LOW was followed for a couple of days to near 26N, 166W at
  0600 UTC on 3 Aug but showed no signs of re-intensification.

                       Hurricane Estelle  (TC-06E)
                              29 July --->

     Hurricane Estelle formed several hundred miles to the east of where
  Darby had developed, but followed a similar general west-northwesterly
  course out into the Central Pacific.   The first advisory on Tropical
  Depression 06E was issued at 1800 UTC on 29 Jul with the system
  centered about 150 nm south-southwest of Acapulco.   Tropical storm
  intensity was attained 12 hrs later about 275 nm south-southeast of
  Manzanillo, and Estelle was upgraded to a hurricane at 31/0600 UTC
  when the storm was located about 500 nm south of Mazatlan, Mexico.
  The TPC/NHC discussion at 0300 UTC noted that Estelle had a large
  circulation that featured a strong core of central convection with
  several rainbands containing convection of moderate intensity.  The
  bulletin accompanying the 1500 UTC advisory mentioned that convective
  tops in the storm's central region were reaching -80 deg C.

     By 0000 UTC on 1 Aug Hurricane Estelle was passing about 450 nm
  south of Cabo San Lucas with MSW estimated at 75 kts.  Although as of
  this writing Estelle has dissipated in the Central Pacific, since the
  storm reached its peak intensity after 1 Aug,  further details of
  Estelle's history will be contained in the August summary.


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

  Activity for July:  2 tropical depressions
                      1 tropical storm

  NOTE: Most of the information on each cyclone's history presented in
  the narrative will be based upon JTWC's advisories, and references to
  winds should be understood as a 1-min avg MSW unless otherwise noted.
  However, in the accompanying tracking document I have made comparisons
  of coordinates with JMA (Japan) and the Philippines (PAGASA) when their
  positions differed from JTWC's by usually 40-50 nm or more.  Also, as
  announced earlier in a separate posting, a column of 10-min avg MSW
  is included--the values being obtained from either PAGASA's or JMA's
  advisories.  A special thanks to Michael V. Padua, owner of the Typhoon
  '98 webpage, for sending me the PAGASA tracks.

     In the title line for each storm I plan to reference all the cyclone
  names/numbers I have available:  JTWC's depression number and name (if
  any), JMA's tropical storm numeric designator, and PAGASA's name for
  systems forming in or passing through their area of responsibility.

                   Tropical Depression Akang  (TC-01W)
                               7 - 11 July

     The first tropical depression of 1998 was first identified by JTWC
  at 1200 UTC on 7 Jul about 400 nm east-southeast of Okinawa.    The
  system moved erratically for a couple of days, and then followed a
  fairly smooth west-northwesterly trajectory which took it through the
  extreme southernmost Ryukyu Islands and into northern Taiwan.    On
  8 Jul PAGASA initiated bulletins on the depression and named it Akang.
  Tropical Depression Akang battled vertical wind shear throughout its
  life and never became very well-organized.    By 09/0000 UTC most of
  the central convection had been sheared toward the southwest, leaving
  a completely exposed low-level center.  The shear continued, causing
  the low-level circulation to become elongated.

     Akang limped ashore onto the northern tip of Taiwan near Taipei,
  and was dissipating by 0000 UTC on 11 Jul.   MSW were estimated at
  30 kts with an estimated minimum pressure of 1002 mb (from JMA's

                Tropical Storm Nichole  (TC-02W / TS 9801)
                                8 - 12 July

     The Northwest Pacific basin's first tropical storm of 1998 was named
  on 8 July,   making this year the latest-beginning tropical storm
  season in that basin at least since 1959.  (This bit of information
  came from Mark Lander of the University of Guam.)     A tropical
  depression had formed in the northern South China Sea between China
  and northern Luzon by 08/0000 UTC.  The first JTWC advisory placed the
  center about 250 nm east-southeast of Hong Kong.    TD-02W drifted
  northward, becoming Tropical Storm Nichole at 1800 UTC.  A small CDO
  had developed and outflow had increased on the southern side of the

     Over the next couple of days Nichole appeared to describe a small
  clockwise loop just west of the southern tip of Taiwan.   The JTWC
  advisory issued at 10/0300 UTC stated that local station information
  indicated a landfall on Taiwan had been made near 09/1740 UTC and
  that synoptic observations supported minimal tropical storm intensity
  at the time.     Peak intensity of 45 kts (with an estimated minimum
  pressure of 998 mb) was reached about that time.  Nichole was down-
  graded to a depression at 0600 UTC on 10 Jul as it drifted westward
  in the Taiwan Straits.

     During this time the system remained poorly organized with an
  exposed low-level center and limited convection sheared to the south
  side of the center.  After 12/0600 UTC the weak depression turned
  northward and was dissipating inland over China by 1800 UTC.

                      Tropical Depression  (TC-03W)
                              24 - 27 July

     This tropical depression was associated with what seems to have
  been a rather complex weather system east of Japan in late July.  In
  fact, it might be more appropriate to say "depressions" since the
  circulation carried in JMA High Seas Forecasts on 24 and 25 July
  appears to have been a distinct center from that identified by JTWC as
  TD-03W beginning at 25/0000 UTC.  The Significant Tropical Weather
  Advisory (STWA) issued at 25/0100 UTC mentioned a large gyre-like upper
  LOW off the east coast of Japan with numerous vorticity maxima in its
  periphery.    Special attention was called to two distinct centers.
  One was a low-level circulation near 28N, 142E (about 200 nm north-
  northeast of Iwo Jima), and this appears to be the center that had been
  carried by JMA for about 24 hrs.    The first JMA bulletin on that
  depression was issued at 0000 UTC on 24 Jul and placed the center about
  300 nm east of Iwo Jima.   It had moved generally in a northwesterly
  direction to the aforementioned coordinates.   Maximum winds reported
  by JMA were 30 kts (10-min avg).     The STWA mentioned that an area of
  deep convection might be wrapping around the periphery of the broad
  cyclonic circulation but that the convection was located over 80 nm
  from the exposed center.   MSW was estimated to be only 15-20 kts with
  a central pressure of 1004 mb.

     The same STWA mentioned another area of convection near 26N, 149E
  which was associated with a rapidly developing circulation that was
  tracking toward the north.  It was apparently this center that JTWC
  classified as TD-03W.  The depression was located about 425 nm east-
  northeast of Iwo Jima at 25/0000 UTC and was moving north-northwestward
  at a fairly quick pace.    The center that had been tracked by Japan
  on 24 Jul was followed to near 29N, 141E by 25/1200 UTC but was
  subsequently dropped from the High Seas Forecasts.

     TD-03W tracked northward east of Japan, passing about 250 nm east
  of Tokyo around 0300 on the 26th.  By 1800 UTC on 25 Jul the low-level
  center had become exposed about 35 nm from the nearest convection.
  By 26/0000 UTC there was no deep convection remaining near the center.
  On 26 Jul the weakening depression turned to the north-northeast and
  accelerated away from Japan. The system had initially been forecast to
  reach tropical storm intensity, but the vertical shear it encountered
  thwarted any further strengthening.


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

  Activity for July:  No tropical cyclones

             Additional Information on Arabian Sea Cyclone
                         (TC-03A)  4 - 9 June

     The author has uncovered a little more information on the effects
  of the deadly Arabian Sea cyclone (TC-03A) which devastated the coast
  of northwestern India in early June.    The source for this was the
  website of the UN Office for the Coordination of Humanitarian Affairs
  (OCHA) - .  According to this report (dated
  19 Jun 1998), 1126 bodies had been recovered but the death toll could
  be as high as 3000 in the Kutch-Saurashtra region of Gujurat.   About
  1745 persons were still missing and 893 were reported injured.  The
  number of houses/huts damaged was put at 158,000 and financial loss
  was estimated at Rs. 120 billion (about 3.01 billion U.S. dollars).
  In addition, in Rajasthan District, 11 persons died and 14,603 houses/
  huts were damaged.


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

  Activity for July:  1 tropical depression

  NOTE:  The information presented below was gleaned from releases by
  the La Reunion TCWC, which is the WMO's Regional Specialized Meteor-
  ological Centre (RSMC) for the South Indian Ocean; and also from
  warnings issued by JTWC.   References to sustained winds imply a
  10-min averaging period unless otherwise stated.  A special thanks
  to Alain Soulan and Paul Remois for passing along some information
  on nomenclature and warning practice in this basin.

                    Tropical Depression "H4"  (TC-01S)
                              20 - 25 July

     First, a few comments about cyclone nomenclature and classification
  in the South Indian basin:

  (1)  La Reunion utilizes a more rigid and restrictive definition of the
       term "tropical depression" than do most TCWC's.  To be classed as
       a tropical depression a disturbance must be adjudged to have a
       10-min MSW of at least 28 kts (i.e., Beaufort force 7).  Weaker
       systems for which advisories are issued are called "tropical

  (2)  In the South Indian basin the term "tropical cyclone" is reserved
       for systems which reach a 10-min MSW of 64 kts--hurricane force.
       Depressions are named when 10-min MSW exceed 34 kts and are
       called "tropical storms", as in U.S. and Japanese usage.  When
       MSW exceed 47 kts (storm force) the system is called a "severe
       tropical storm".

  (3)  Whenever a tropical disturbance has become sufficiently organized
       to warrant advisories being issued, the disturbance is given a
       two-character designator.  The first character is the initial
       letter of the next cyclone name on the annual list (in this case,
       Hillary).  The second character is a digit which is a sequential
       count of significant disturbances occurring since the last storm
       was named.   Thus, "H4" was the fourth disturbance occurring
       since Tropical Storm Gemma was named in April, but was the first
       of these to reach tropical depression intensity.

  (4)  In the South Indian basin the tropical cyclone season is
       considered to run from 1 Aug to 31 Jul instead of from 1 Jul to 30
       Jun, as is the case with Australia and Fiji.  But JTWC's numbering
       scheme for Southern Hemisphere tropical depressions and cyclones
       starts anew on 1 Jul each year; hence, this depression was
       considered by JTWC to be the first of the 1998/99 season while
       La Reunion will regard it as the last one of the 1997/98 season.

     The first advisory by La Reunion was issued at 0600 UTC on 20 Jul
  with the disturbance centered about 800 nm east of Diego Garcia.  The
  system moved rather slowly toward the west-southwest for a couple of
  days.  It was upgraded to a tropical depression with 30-kt MSW at
  0600 UTC on 22 Jul.   The center was estimated to be about 400 nm
  east-southeast of Diego Garcia at this time.    By 23/0000 UTC the
  system was showing signs of weakening and was downgraded to a tropical
  disturbance.   Interestingly, it wasn't until 0600 UTC on the 23rd
  that JTWC issued its first advisory, placing the depression center
  about 300 nm southeast of Diego Garcia.

     La Reunion dropped the system 6 hrs later, but JTWC continued
  issuing advisories until 25/0000 UTC.     During this period the
  center stalled and began to drift northward and then to the east-
  northeast.   The final advisory located the center about 300 nm east-
  southeast of Diego Garcia.

     This depression experienced considerable vertical shear throughout
  its life.    At 1800 UTC on 21 Jul the system exhibited an exposed
  center with the nearest organized convection about 60 nm distant.
  By early on the 23rd the shear had abated somewhat and the low-level
  circulation appeared to be better organized.   Given the proximity
  to Diego Garcia and the slight possibility that the system might
  reach tropical storm strength, JTWC decided to initiate advisories.


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

  Activity for July:  No tropical cyclones


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

  Activity for July:  No tropical cyclones


  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: []
       (b) Login as: anonymous
       (c) For a password use your e-mail address
       (d) The files will be named with an obvious nomenclature--using
           July as an example:   jul98.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 July summary is the tenth 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 websites
  (courtesy of Michael Bath and Michael V. Padua):>> (since January only)

    The preliminary storm reports for all the 1997 Atlantic and Eastern
  North Pacific tropical cyclones are available on the Tropical
  Prediction Center's website:> .  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:>

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



  AOML/HRD - Atlantic Oceanographic and Meteorological Laboratory/
             Hurricane Research Division, located on Virginia Key, Miami,
             Florida, U.S.A.

  AOR -     area of responsibility

  CDO -     central dense overcast

  CPHC -    Central Pacific Hurricane Center, Honolulu, Hawaii, U.S.A.

  FLW -     flight level winds

  FTP -     file transfer protocol

  IMD -     India Meteorological Department (RSMC New Delhi, India)

  JMA -     Japanese Meteorological Agency (RSMC Tokyo, Japan)

  JTWC -    Joint Typhoon Warning Center, Guam

  kt -      knot = 1 nautical mile per hour

  m -       meter, or metre

  mb -      millibar, numerically equivalent to hectopascal

  mm -      millimeter

  MSW -     maximum sustained wind(s) (either 1-min avg or 10-min avg)

  nm -      nautical mile = 6076.12 feet or 1852.0 meters

  NPMOC -   Naval Pacific Meteorological and Oceanographic Center, Pearl
            Harbor, Hawaii, U.S.A.

  PAGASA -  Philippines' Atmospheric, Geophysical & Astronomical Services

  RSMC -    Regional Specialized Meteorological Centre

  SST -     sea surface temperature

  STS -     severe tropical storm (MSW greater than 47 kts)

  TC -      tropical cyclone

  TCWC -    Tropical Cyclone Warning Centre (generic term)

  TD -      tropical depression

  TPC/NHC - Tropical Prediction Center/National Hurricane Center, Miami,
            Florida, U.S.A.

  TS -      tropical storm

  WMO -     World Meteorological Organization, headquartered at Geneva,

  UTC -     Universal Time Coordinated, equivalent to Greenwich Mean Time
            or Zulu (Z)


Document: summ9807.htm
Updated: 18th March 2008

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