[Index]
Monthly Global Tropical Cyclone Summary May 2002
[Summaries and Track Data] [Prepared by Gary Padgett]
| Tropical
Cyclones
[Index] |
Monthly Global Tropical Cyclone Summary May 2002 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
MAY, 2002
(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.)
*************************************************************************
MAY HIGHLIGHTS
--> Tropics very busy for month of May
--> Minimal hurricane strikes northern Madagascar
--> Oman experiences rare tropical cyclone strike
--> Another western Pacific super typhoon forms
--> Rare tropical cyclone forms near Papua New Guinea
*************************************************************************
***** Feature of the Month for May *****
SOME OF MY FRIENDS' OUTSTANDING WEBSITES
In the Feature of the Month in the April summary I introduced an
e-mail discussion group with whom I discuss tropical cyclones, share
information, ask questions, answer questions, etc. Many of the group
members have tropical cyclone and/or weather-related websites which are
very interesting and informative. For this month's Feature I wanted to
list these websites, giving the URLs as well as a few brief comments
about each. The websites are listed alphabetically by the last name of
the owner.
1. AUSTRALIA SEVERE WEATHER Owner: Michael Bath
Link: http://www.australiasevereweather.com
Michael Bath, who lives near Wollongbar in northeast New South Wales,
is an avid photographer, storm chaser, and weather enthusiast. The
website was designed and is maintained by Michael and his chase
partner Jimmy Deguara. There are links to such topics as severe
weather reports, storm chasing, weather photography, tornadoes,
weather observations, and of course tropical cyclones. The tropical
cyclone page contains a wealth of information including links for
satellite images, tropical weather advisories for the Pacific and
Indian Oceans, and annual cyclone track maps for the Australian
Region dating back many years. Also available are some statistics
on Southern Hemisphere tropical cyclones compiled by Patrick Hoareau,
and histories of significant tropical cyclones impacting the East
Coast of Australia as well as the Gulf of Carpentaria coastline.
2. OURAGANS.COM Owner: Bruno Benjamin
Link: http://www.ouragans.com
Bruno Benjamin is a tropical cyclone enthusiast who lives on the
French island of Guadeloupe in the eastern Caribbean Sea. Bruno's
goal was to create a tropical cyclone website completely in French
covering storms all around the globe. ("Ouragan" is the French word
for hurricane.) There are links to separate sections for cyclone
coverage of the Oceans Atlantique, Indien, and Pacifique. Also
included are links to information on historical hurricanes in the
Antilles, and also maps and additional information about several of
the islands in the Lesser Antilles.
3. ATLANTIC TROPICAL WEATHER CENTER Owner: Eric Blake
Link: http://www.atwc.org/
Eric Blake, a native of Mandeville, Louisiana, and a graduate of
Colorado State University, is now employed in the Tropical Analysis
and Forecasting Branch (TAFB) at TPC/NHC. Eric's website is the
home of links, links, links, and more links. The ATWC is a
veritable gold mine of information, and since it is overwhelmingly
just links, it loads very quickly, even on a fairly slow connection.
There are links to NHC advisories, surface observations, buoy and
ship reports, SST charts, reconnaissance flight messages, satellite
pictures, scatterometer data, radar images, numerical model output,
and many, many other topics. The one hitch is that is primarily
limited to information about the Atlantic basin only, so those
looking for Pacific and Indian Ocean tropical cyclone information
will not find too much here.
4. JIM EDDS VIDEOGRAPHY & PHOTOGRAPHY Owner: Jim Edds
Link: http://www.hurricanechase.com
Jim Edds is a videographer and photographer who lives in Big Pine
Key, Florida, and works for the Florida Department of Environmental
Protection. Jim moved to the Keys from Northwest Florida in 1993,
and got his first taste of hurricane chasing when Georges moved
through the Keys in 1998. Since then Jim has photographed many
tropical cyclones and waterspouts with much of his footage being
aired on The Weather Channel in Atlanta, Georgia. Jim's website
contains his biography plus many examples of his photographic work.
There are many interesting links to check out, two in particular
being Dr. Jeffery Masters' hair-raising account of a near-fatal
reconnaissance mission into Hurricane Hugo in September, 1989, and
Jerry Wilkinson's pictorial history of the extremely intense 1935
Labor Day Hurricane in the Florida Keys.
5. PUERTO RICAN HURRICANE PAGE Owner: Jose Garcia
Link: http://www.geocities.com/huracanado1/
Jose Garcia, who lives in Gurabo, Puerto Rico, just turned 17 years
of age a few days ago. Jose's website, as the name implies, is
dedicated to covering hurricanes which have affected Puerto Rico
down through the centuries from 1500 onward. The background for
the main page is a very impressive, clear, high-resolution visible
image of mighty Hurricane Gilbert about the time of its peak inten-
sity of 160 kts and 888 mb. Jose's site also contains links to
several tropical cyclone warning centers and various tropical
cyclone-related websites.
6. EGLIN AFB TROPICAL WEATHER PAGE Webmaster: Rich Henning
Link: http://www.eglin.af.mil/weather/tropics.html
Rich Henning is a Staff Meteorologist at Eglin AFB in Northwest
Florida--also a member of the Hurricane Hunters Squadron--and is the
webmaster for the USAF's 46th Weather Squadron's weather page. High-
lights include Rich's comments about tropical weather systems around
the globe, automatically updated satellite pictures covering the
world's tropical cyclone basins, and many, many tropical cyclone
and other weather-related links. One interesting feature is a
history of tropical cyclones known to have affected the Florida
Panhandle since the colonial period. A couple of years ago Rich
updated the original document, which was written in the early 1970s,
and I assisted him with editing and proofreading.
7. METEO DU SUD-OUEST DE L'OCEAN INDIEN Owner: Jean Paul Hoarau
Link: http://www.jean-paul.hoarau.com
Jean Paul Hoarau, who lives on Reunion Island in the Southwest Indian
Ocean, is the younger brother of Karl Hoarau. Jean Paul's website
is another French-language tropical cyclone website and is devoted
to covering primarily the Southwest Indian Ocean. Jean Paul receives
satellite imagery directly from the MeteoSat5 satellite, which is
parked over the Indian Ocean, and also from some of the NOAA polar
orbiters, and these are available for viewing on the website. Also
included are links to pages detailing several intense Southwest
Indian Ocean cyclones and some Western Pacific Typhoons.
8. HURRICANE WARNING - CYCLONE JIM Owner: Jim Leonard
Link: http://www.cyclonejim.com/
Jim Leonard, who lives in Islamorada in the beautiful Florida Keys,
has become one of the best known tornado and hurricane chasers and
photographers in the United States. Jim is also a very serious
amateur meteorologist who has studied weather and tropical cyclones
intensely over the years and has become very knowledgeable about the
science of meteorology. Jim's website contains many pictures and
video clips of his chasing experiences as well as a history of his
chasing career. Also included are quite a few links to various
tropical weather sites, satellite images, and links to several storm
chasers' homepages.
9. GEOFF MACKLEY - FILM MAKER Owner: Geoff Mackley
Link: http://www.geoffmackley.com/
Geoff Mackley from New Zealand is a very experienced, far-travelled
photographer and videographer who travels around the world shooting
footage of severe weather and volcanoes. Some of Geoff's other
interests include caving, mountaineering, and mountain biking. His
website, which is updated frequently, contains some breathtaking
shots of his latest adventures as well as information on current
tropical cyclones. There are photo galleries of many Southern
Hemisphere severe weather events: cyclones, floods and snowstorms
as well as hurricanes, typhoon, and volcanic eruptions.
10. TYPHOON2000.COM Owner: Michael V. Padua
Link: http://www.typhoon2000.ph/
Michael Padua of Naga City on Luzon in the Philippines began his
typhoon website in 1998 when it was called Typhoon '98. The name
later changed to Typhoon '99, but after 2000 arrived Michael says he
decided to leave it as Typhoon 2000 for the next millennium. The
site contains a wealth of information about Northwest Pacific trop-
ical cyclones, both current and historical. Links to warnings from
several Western Pacific warning agencies are included, as well as
links to satellite images, news reports, and storm archives. There
is also a discussion forum available, and small satellite animations
of currently-progressing tropical cyclones.
11. MIKE'S HURRICANE TRACKING Owner: Michael Pitt
Link: http://mpittweather.com
Michael Pitt is a weather technician and observer in the U. S. Navy.
His website focuses primarily on hurricane tracking in the Atlantic
and Northeast Pacific basins, but links are provided for obtaining
information on other basins. A Tropical Weather Archives Page
provides links to TPC/NHC reports on Atlantic and Eastern Pacific
storms as well as to the UK Meteorological Office's monthly bulle-
tins. As usual there are many links to tropical cyclone and other
weather-related websites as well as automatically updated infrared
satellite imagery covering the tropical cyclone basins.
12. CYCLONE INFORMATION AND TRACKING MAPS Owner: Carl Smith
Link: http://users.qldnet.com.au/~carls/
Carl Smith lives on the Gold Coast in southeastern Queensland, and
says he has been fascinated by severe weather since he was a child.
In 1975, when a young man, Carl and his family rode out a very
fierce tropical cyclone (Joan) when it made landfall in Western
Australia. Carl's website provides links to information on all
currently-operating tropical cyclones as well as links to archived
information on Australian tropical cyclones of recent years. Also
available are detailed tracking maps of the cyclone-prone regions
of Australia which may be downloaded.
13. PHIL'S TYPHOONS, HURRICANES AND CYCLONES PAGE Owner: Phil Smith
Link: http://www.drdisk.com.hk/cyclones.htm
Phil Smith is the elder brother of Carl and although a native of
Australia, has lived in Hong Kong for many years where he is employed
as a computer consultant. Phil's site also contains links to infor-
mation on all currently-operating tropical cyclones as well as many
other links to tropical cyclone and other weather-related sites,
including special pages with map animations for some recent Hong
Kong tropical cyclones. There are also tracking maps available for
the South China Sea region, including southern mainland China,
Vietnam, the Philippines and Taiwan.
14. EYE IN THE TROPICS Owner: Mike Theiss
Link: http://www.mthurricane.com
Mike Theiss is a young storm chaser who lives in Key Largo, Florida,
and when not chasing tornadoes and hurricanes often helps out at his
father's snorkel company. Mike learned much about meteorology and
chasing from his friend and teacher, Jim Leonard. Like Jim Leonard's
and Jim Edd's websites, Mike's has beautiful photographs he's made
of waterspouts, hurricanes, lightning and magnificent Florida Keys'
sunsets. Naturally there are links to other storm chasers' homepages
and to various other weather-related sites. There is also a page
describing the Theiss-Device--a (hopefully) tornado-proof aluminum
box with bullet-proof glass windows which Mike designed and built
and containing a camera inside--the idea being to place it in front
of an oncoming tornado and get the "Ultimate Footage of a tornado
up close and personal."
Now, with all this information about these outstanding websites, hope-
fully everyone will visit them and explore the many interesting features
and links contained therein. Collectively, they provide an almost com-
plete compendium of "everything you always wanted to know about tropical
cyclones but were afraid to ask".
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ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for May: No tropical cyclones
Atlantic Tropical Activity for May
----------------------------------
While the official Atlantic hurricane season does not begin until
1 June, the month of May has had enough tropical cyclones, subtropical
storms, and tropical disturbances over the years to warrant being con-
sidered a significant prelude to the hurricane season. Since 1886
there have been twelve tropical storms or hurricanes known to have
formed in the month of May. Only three of these--a storm in 1889, Able
in 1951, and Alma in 1970--reached hurricane intensity. The last named
tropical storm in May was Arlene in 1981. Subtropical storms have also
developed in May. Two of these systems (in 1972 and 1976) reached the
U. S. coastline with gale-force winds. There have been other systems
in later years which possibly were subtropical storms and may eventually
be added to the official Best Track file pending further analysis.
Neither is it all that unusual for a tropical depression to form during
May--within the last 15 years the first official tropical depression of
the season formed prior to 1 June in 1987, 1988, 1990 and 1993.
There were no tropical or subtropical storms nor any depressions in
May, 2002, but there were a couple of disturbances which elicited the
issuance of Special Tropical Disturbance Statements from TPC/NHC. An
area of showers and thunderstorms accompanied by a broad area of low
pressure had developed over the northwestern Caribbean Sea by 23 May.
Upper-level winds were quite hostile for tropical development, but heavy
rains occurred over Jamaica and eastern Cuba for several days. No
reconnaissance flights were made into the region, although some were
planned in case the disturbance began to show signs of development.
The other system was a surface LOW which formed on 28 May about 200 nm
east of Daytona Beach, Florida. A small, well-defined swirl in the low
clouds could be seen in visible imagery, but the convective activity was
located over 100 nm away from the center and never was able to become
established over or near the LLCC. The LOW drifted generally westward
for a couple of days and then weakened. No reconnaissance missions were
flown into this system either.
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for May: 1 hurricane
Sources of Information
----------------------
Most of the information presented below was obtained from the
various tropical cyclone products issued by the Tropical Prediction
Center/National Hurricane Center (TPC/NHC) in Miami, Florida (or the
Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii, for
locations west of longitude 140W): discussions, public advisories,
forecast/advisories, tropical weather outlooks, special tropical
disturbance statements, etc. Some additional information may have
been gleaned from the monthly summaries prepared by the hurricane
specialists and available on TPC/NHC's website. All references to
sustained winds imply a 1-minute averaging period unless otherwise
noted.
The summary on Hurricane Alma was written by John Wallace of
San Antonio, Texas. John has written most of the Northeast Pacific
cyclone summaries over the past two seasons and some of the write-ups
for North Indian Ocean cyclones. Because of his special interest in
the storms and climatology of these two basins and his willingness to
continue writing the summaries, I have listed John as a co-author at
the end of this document. His e-mail address is included there. A
special thanks to John for the assistance he so dependably lends.
Northeast Pacific Tropical Activity for May
-------------------------------------------
TPC/NHC considers 15 May as the beginning of the official Eastern
North Pacific tropical cyclone season, and indeed the first named storm
of the year makes it appearance in May more than 50% of the time. This
year was no exception, becoming the third year in a row to produce a
hurricane during the latter part of May. A tropical depression formed
on the 24th well south of Acapulco and drifted slowly westward. By the
26th the system had strengthened into a tropical storm and was named
Alma. Alma subsequently turned northward and intensified into a
95-kt hurricane, but then encountered strong upper-level shear which
caused the cyclone to quickly weaken and dissipate. Within 48 hours
after reaching its peak intensity, Alma had been reduced to a non-
convective swirl of low clouds. (NOTE: The CPHC in Honolulu does not
begin issuing regular tropical weather outlooks until 1 June for the
portion of the NEP basin lying between 140W and the Dateline.)
HURRICANE ALMA
(TC-01E)
24 May - 1 June
-----------------------------------
A. Storm Origins
----------------
Alma was the third consecutive May hurricane, the first time on record
(beginning with 1971) that such an event has occurred. The fact that it
was uncommonly intense for a May storm secures its record further--only
two other May storms have equaled or exceeded a MSW of 95 kts.
The area of disturbed weather that became Alma was first noted on
22 May while well southwest of Acapulco, Mexico. It remained ill-defined
until the 24th, when its organization increased enough to warrant its
upgrade to Tropical Depression One-E at 2100 UTC, located 325 nm south of
Acapulco.
The depression's first day was difficult--modest northeasterly shear,
combined with interference from the ITCZ in which it was embedded,
hindered its development. One-E initially took an uncharacteristic slow,
southwesterly track, probably along the isobars of the similarly oriented
ridge to its north. Its organization improved beginning early on the
26th. Satellite data warranted its upgrade to Tropical Storm Alma at
0900 UTC, located 515 nm southwest of Acapulco, in spite of northeast-
erly shear that exposed its LLCC. The ragged cyclone held on to
minimal tropical storm status as it tracked slowly to the west.
B. Track and Intensity History
------------------------------
Late on the 27th, Alma's fortunes changed and it intensified steadily;
its track bent west-northwestward along the periphery of the subtropical
ridge. A transient eye became visible, and Alma was upgraded to hurri-
cane status at 2100 UTC on 28 May when located about 680 nm southwest of
Manzanillo, Mexico.
The ridge north of Alma was eroded by an upper-level LOW on the 29th
and the system turned northwest accordingly. By the 30th, Alma was bear-
ing due north, and it intensified quickly--by 0300 UTC T-numbers from
the TAFB were as high as T5.5 - T6.0 (102-115 kts). The forecaster on
duty stated that because the Dvorak technique often overestimated the
intensity of strengthening NEP storms, the MSW was adjusted to a
conservative 90 kts at 0300 UTC. Alma's MSW peaked at 95 kts at 1500
UTC on 30 May, with an estimated CP of 965 mb, while located roughly
630 nm west of Manzanillo. This estimate was conservative, however, as
TAFB and SAB estimates were at T5.5 at this time. Alma commenced a
weakening trend immediately afterward due to increasing shear and cooler
SSTs. Interestingly, CI estimates remained at 100 kts until 2100 UTC.
Alma decelerated and became quasi-stationary on the 31st as steering
currents collapsed. The cyclone weakened rapidly, dropping below hurri-
cane strength at 1500 UTC on the 31st--by then most of its convection
had been stripped away by shear, or starved by cool SSTs and dry air.
Alma weakened to depression strength at 0300 UTC on the 1st, its central
pressure having risen 27 mb in only a day. The final advisory on Trop-
ical Depression Alma was issued at 1500 UTC on 1 June when it was located
roughly 650 nm west of Manzanillo. A remnant vortex persisted in the
region until 4 June.
C. Damage and Casualties
------------------------
No casualties or damage are known to have resulted from Hurricane
Alma.
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for May: 1 tropical depression
1 super typhoon
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located at Pearl Harbor, Hawaii. In the companion
tropical cyclone tracks file, I normally annotate track coordinates
from some of the various Asian warning centers when their center
positions differ from JTWC's by usually 40-50 nm or more. All
references to sustained winds imply a 1-minute averaging period
unless otherwise noted.
Michael V. Padua of Naga City in the Philippines, owner of the
Typhoon 2000 website, normally sends me cyclone tracks based upon
warnings issued by the Japanese Meteorological Agency (JMA) and the
Philippines' Atmospheric, Geophysical & Astronomical Services
Administration (PAGASA). Also, Huang Chunliang of Fuzhou City, China,
sends me each month tracks obtained from warnings issued by the
National Meteorological Center of China (NMCC), the Central Weather
Bureau of Taiwan (CWBT) and the Hong Kong Observatory (HKO). A very
special thanks to Michael and Chunliang for the assistance they so
reliably provide.
In the title line for each storm I have referenced 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 warning responsibility.
Northwest Pacific Tropical Activity for May
-------------------------------------------
Two tropical cyclones formed in May in the Northwest Pacific basin.
One of these remained a tropical depression, but the other intensified
into the year's second super typhoon (per JTWC's warnings). The storm,
Hagibis, formed a couple hundred miles south of Guam, moved westward,
then turned northward, passing west of the Marianas Islands. Typhoon
Hagibis did not reach its peak intensity of 140 kts until after it had
recurved and was moving northeastward.
Tropical Depression 06W, named Dagul (meaning a big man) by PAGASA,
formed in the South China Sea approximately 425 nm west-northwest of
Manila at 0600 UTC on 27 May (per JMA's warnings). JTWC and PAGASA
began issuing warnings on the system at 28/0000 UTC when it was located
roughly 375 nm northwest of Manila. TD-06W/Dagul moved slowly in a
general north-northeasterly direction, reaching a point about 85 nm
west of the southern tip of Taiwan by 1200 UTC on the 29th. PAGASA
and JMA estimated the 10-min avg MSW at 30 kts, but JTWC's intensity
remained at 25 kts throughout the period of warning. The 29/1200 UTC
warning was the final one issued by JTWC, but PAGASA followed the system
through 30/0000 UTC and JMA issued bulletins through 1800 UTC on 30 May.
PAGASA's coordinates take the center of Dagul across southern Taiwan,
but JMA's 29/1200 UTC position was well to the south and east of JTWC's
and PAGASA's. JMA's track takes the center northeastward, just skimming
the southeastern coast of Taiwan. The final bulletin, at 30/1800 UTC,
located the center approximately 110 nm southeast of Taipei. TD-06W/
Dagul was a broad circulation with the deep convection consistently
displaced to the southeast of the center.
SUPER TYPHOON HAGIBIS
(TC-05W / TY 0203)
15 - 22 May
-----------------------------------------
Hagibis: contributed by the Philippines, means swift, or fast.
A. Storm Origins
----------------
JTWC issued a STWO at 13/0100 UTC for an area of convection that was
developing approximately 300 nm south of Chuuk. A broad area of cycling
deep convection was associated with a weak LLCC, and a 200-mb analysis
indicated that the system lay within a region of moderate diffluence.
By 0600 UTC the system had moved to a position roughly 250 nm south-
southwest of Chuuk. An upper-level trough to the northeast and an upper-
level LOW to the northwest were providing good divergence over the
system, so the development potential was upgraded to fair. A TCFA was
issued at 1600 UTC--deep convection was increasing in the southwestern
quadrant and a good poleward outflow channel had become established.
The TCFA was re-issued at 1600 UTC on the 14th. Recent QuikScat and
TRMM passes indicated that the LLCC was situated in a monsoon trough
extending from Palau. The center was better depicted in 85 GHz imagery
than in the 37 GHz band. The LLCC remained equatorward of the sub-
tropical ridge axis with the stronger winds and convective bands located
south of the center. Upper-level southeasterlies, which had been
creating some shear, had weakened during the previous 12 hours to an
average speed of 10-15 kts.
JTWC issued the first warning on Tropical Depression 05W at 0000 UTC
on 15 May, placing the center approximately 190 nm southwest of Chuuk.
The system was located in a monsoon trough extending eastward from Palau.
The initial warning intensity was estimated at 25 kts, and satellite ani-
mation depicted convective bands developing to the northeast and south-
west of the LLCC. The depression continued moving generally northwest-
ward and by 1200 UTC was located about 375 nm south-southeast of Guam.
The MSW had been increased to 30 kts at 0600 UTC, and a 15/1126 UTC SSM/I
pass indicated two banding features, one to the west and one to the south
of the center. Satellite intensity estimates at 1800 UTC were 30 and
35 kts, but the MSW remained at 30 kts for the concurrent warning. The
LLCC was displaced to the east of the mid-level circulation, although
deep convection was increasing in organization.
B. Track and Intensity History
------------------------------
JTWC upgraded TD-05W to tropical storm status at 16/0000 UTC while
also relocating the center 120 nm to the west of the previous warning
position. Satellite imagery indicated that the circulation had consol-
idated to the west nearer the deeper convection. The cyclone's center
was located approximately 180 nm south-southeast of Guam, moving north-
westward at 15 kts. At 0600 UTC satellite CI estimates were spread out
from 25 to 45 kts--JTWC held the MSW at 35 kts for the time being. Deep
convection was confined to the northern and western quadrants. The
center of TS-05W passed a little over 100 nm south of Guam around 0900
UTC, and at 1200 UTC was located about 90 nm southwest of the island,
still trekking northwestward. Convection had deepened near the LLCC,
and JMA and NMCC upgraded the system to tropical storm status with JMA
assigning the name Hagibis. Intensity estimates at 1800 UTC were 35
and 45 kts, and both JTWC and JMA increased their respective MSW values
to 40 kts. Tropical Storm Hagibis was then located roughly 150 nm west
of Guam and had turned to more of a west-northwesterly heading. Animated
water vapor imagery indicated improved outflow as a shortwave trough
approached from the northwest--convection had responded by increasing
significantly near the LLCC.
Hagibis steadily increased in intensity on 17 May. The storm was
located approximately 230 nm west of Guam at 17/0000 UTC with peak winds
estimated at 50 kts. A 16/2128 UTC microwave pass had depicted a band-
ing eye feature, and early morning visible imagery indicated a signifi-
cant increase in deep convection. JTWC upped the MSW by 5 kts on each
warning and at 1800 UTC Hagibis was upgraded to a typhoon. This was
based on CI estimates of 65 kts, a strong banding feature wrapping in
from the north, and newly-developed deep convection over the center.
Typhoon Hagibis was located roughly 370 nm west of Saipan and was at
the westernmost point of its track--the storm's motion thereafter was
northward or northeastward. By 0000 UTC on the 18th Hagibis was tracking
northward west of Saipan. JMA upgraded the storm to typhoon status with
65-kt winds--JTWC's estimated MSW was also 65 kts. At 1200 UTC Typhoon
Hagibis was centered approximately 350 nm west-northwest of Saipan and
was moving northeastward at 8 kts. (NMCC upgraded Hagibis to typhoon
status at this time.) JTWC increased the intensity to 80 kts, based on
CI estimates of 77 and 90 kts. The storm's track was being influenced
by a poleward-oriented (southwest to northeast) mid-level ridge and a
major shortwave trough to the northwest of the typhoon.
JTWC increased the MSW to 90 kts at 18/1800 UTC and to 120 kts at
0000 UTC on the 19th, based on CI estimates of 115 and 127 kts. The
typhoon was located about 425 nm south of Iwo Jima and tracking slowly
northeastward. Visible and enhanced infrared imagery had revealed the
development of a convective eye ring feature over the previous six hours,
which had contributed to a rapid intensification period, and a cloud-free
13-nm diameter eye. The MSW was upped to 130 kts at 0600 UTC--making
Hagibis the second super typhoon of the year--and to the peak value of
140 kts at 1200 UTC based on CI estimates of 140 kts. Hagibis was
centered approximately 330 nm south of Iwo Jima or about 165 nm west-
southwest of the northernmost Marianas Islands. The minimum central
pressure estimated by JMA was 935 mb. Gale-force winds extended outward
from the 30-nm diameter eye up to 120 nm in the southeast quadrant while
50-kt winds reached out from 45-55 nm. The typhoon was moving northeast-
ward at 13 kts and this motion had increased to 17 kts by 1800 UTC. The
140-kt intensity was maintained at 1800 UTC but Hagibis was beginning to
show signs of weakening: the eye had become irregular and the outer
convective ring had collapsed on the western side of the storm. The
inner ring, however, was still intact.
At 0000 UTC on 20 May Hagibis was located approximately 225 nm south-
east of Iwo Jima and moving northeastward at 22 kts. During the day the
northeastward motion accelerated considerably--by 1800 UTC the storm was
650 nm east-northeast of Iwo Jima, racing northeastward at 36 kts. The
typhoon's intensity began to drop rapidly as Hagibis began to transition
into an extratropical cyclone. The MSW was reduced to 125 kts at 0000
UTC--just under the super typhoon threshold of 130 kts--as CI estimates
had come down to 115 and 127 kts. The inner convective ring over the
western quadrant had collapsed, and the eye had cooled and become cloud-
filled. A large cirrus shield had developed to the northeast by 0600
UTC due to interaction with the jet stream to the northwest of the
system, and water vapor imagery indicated that a dry slot was being
entrained into the southeastern quadrant. By 1800 UTC JTWC had lowered
the intensity to 90 kts and JMA had reduced their 10-min avg MSW estimate
to minimal typhoon intensity.
At 0000 UTC on the 21st Hagibis was located about 900 nm northeast of
Iwo Jima, racing northeastward at 42 kts. JTWC lowered the MSW to 75 kts
based on CI estimates of 77 kts. Animated water vapor imagery indicated
very little deep convection in the western semicircle and cold-core
cumulus wrapping into the center from the southwestern quadrant--extra-
tropical transition was nearly complete. JTWC and JMA both lowered the
intensity to 60 kts at 21/0600 UTC with JTWC issuing their final warn-
ing. Hagibis was located about 1200 nm west-northwest of Midway, or
about 1000 nm east of Tokyo, moving northeastward at 43 kts. Satellite
imagery revealed marine stratocumulus surrounding the western semi-
circle with rapidly weakening convection. JTWC classified Hagibis as
completely extratropical while JMA maintained the storm as a tropical
cyclone for another 12 hours, declaring Hagibis to be extratropical at
1800 UTC. By 0600 UTC on 22 May the former super typhoon was a weakening
gale near the Dateline far to the south of the Aleutian Islands.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
Intensity estimates between JTWC and JMA were in close agreement up
to the most intense phase of Hagibis' life. JTWC's estimated peak MSW
of 140 kts would be roughly equivalent to a 10-min avg MSW of 120 kts.
JMA's peak intensity of 90 kts was well under this. One surprising thing
was that NMCC's estimated peak 10-min avg MSW was only 80 kts. Typically
for intense typhoons NMCC's estimates are usually higher than those from
JMA.
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Super Typhoon
Hagibis have been received.
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for May: 1 tropical depression **
2 tropical cyclones of gale intensity
** - system classified as tropical depression only by Thailand
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located 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 World Meteorological Organization's Regional
Specialised Meteorological Centre (RSMC) for the basin.
The reported maximum sustained winds (MSW) are based on a 1-minute
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 Ocean region, both 10-minute and
3-minute average winds are employed, but IMD makes no attempt to
modify the Dvorak scale for estimating tropical cyclone intensity;
hence, a 1-minute average MSW is implied. In the North Indian Ocean
basin JTWC usually does not initiate warnings until a system has
become well-organized and likely to attain tropical storm status
within 48 hours.
The summaries below on Tropical Cyclones 01A and 02B were written
by John Wallace.
North Indian Ocean Tropical Activity for May
--------------------------------------------
May is usually the peak month of the spring tropical cyclone season
in the North Indian Ocean, and in 2002 May ran true to form. Two systems
were classified as tropical cyclones by JTWC, and a third system was
treated as a tropical depression by the Thai Meteorological Department.
Tropical Cyclone 01A formed in the Arabian Sea the first week of the
month as the Northern Hemisphere member of a pair of twin tropical
cyclones--Tropical Cyclone Kesiny being the Southern Hemisphere cyclone.
TC-01A made landfall in Oman on the 10th where it reportedly caused
considerable damage.
The MJO impulse which spawned TC-01A and Kesiny continued to push on
eastward and by 10 May had led to the formation of yet another pair
of tropical cyclones--Indian Ocean "quadruplets". The Northern Hemi-
sphere system, Tropical Cyclone 02B, moved northward into Myanmar while
the Southern Hemisphere twin--Errol--wandered about for a few days north-
west of Cocos Island and never intensified above minimal tropical cyclone
intensity.
Another Bay of Bengal system was treated as a tropical depression by
the Thai Meteorological Department only. This system was located about
475 nm southwest of Chittagong at 1500 UTC on 17 May. The system moved
in an east-northeasterly direction and inland into Myanmar. The final
bulletin, at 19/0300 UTC, placed the weakening center about 225 nm
north-northeast of Yangan. JTWC issued a TCFA for the LOW at 17/2000
UTC, but a cancellation was issued at 18/1600 UTC which noted that the
system had moved inland into western Myanmar around 0900 UTC. Huang
Chunliang sent me the Thai track for this system. The maximum winds
were given as 30 kts, and I do not know if this represents a 1-min or
10-min average. Since JTWC estimated the winds at only 20-25 kts in
their STWOs and TCFA, I treated the winds from the Thai bulletins as a
1-min avg MSW in the companion cyclone tracks file. (A special thanks
to Chunliang for sending me the information on this system.)
TROPICAL CYCLONE
(TC-01A)
6 - 10 May
------------------------------------
A. Storm Origins
----------------
The disturbance that became Tropical Cyclone 01A was first noted in
the JTWC STWO on 3 May when it was roughly 60 nm south of Dondra Head,
Sri Lanka. A LLCC was already present at this time, though it was
embedded in an equatorial trough. The incipient disturbance tracked
roughly west-northwestward over the next two days, then turned north-
northwestward on the 5th. Its organization improved significantly on
the 5th as deep convection expanded over its LLCC under an upper-level
ridge. Its organization improved enough to warrant the issue of a TCFA
at 2300 UTC on 5 May, based on satellite data and ship reports of winds
to 25 kts in its eastern and northern quadrants. At 1800 UTC on 6 May
the first warning was issued on Tropical Cyclone 01A, located roughly
715 nm west of Bangalore, India. The cyclone tracked to the northwest
due to the influence of a subtropical ridge to its north.
B. Track and Intensity History
------------------------------
The cyclone reached tropical storm intensity at 0600 UTC on 7 May when
it was centered approximately 815 nm west of Bangalore. It briefly
attained a MSW of 40 kts before weakening to minimal tropical storm
strength due to easterly shear and the entrainment of desert air. The
LLCC was exposed as soon as 1800 UTC on the 7th, a situation that would
persist throughout its life. The storm decelerated and turned westward
before assuming a west-northwesterly track on the 8th.
Tropical Cyclone 01A did not intensify on the 8th. This is interest-
ing in light of the fact that outflow was excellent by late that day,
particularly in the northern semicircle. Its LLCC remained exposed with
the deep convection displaced in the western semicircle. The storm
strengthened slightly on the 9th, reaching its peak MSW of 45 kts at
0600 UTC on 9 May while centered about 240 nm southeast of Mirbat, Oman.
Ship J8CV5 recorded a MSW of 41 kts south of TC-01A's center at approxi-
mately 1200 UTC on the 9th.
The storm turned northwestward and weakened on the 10th due to dry air
entrainment and land interaction. Deep convection shifted to the
southern semicircle, and its LLCC decoupled from the rest of the circu-
lation. Landfall was very near Salalah, Oman, at approximately 0900 UTC
on 10 May with an estimated MSW of 40 kts. The final advisory on TC-01A
was issued at 1200 UTC that day when it was located 70 nm west-northwest
of Mirbat, Oman.
C. Meteorological Observations
------------------------------
Fortuitously, there were two weather stations operating near TC-01A's
point of landfall: one at Al Ghaydah, Yemen, and one at Salalah, Oman.
Al Ghaydah reported a south-southeast wind of roughly 25 kts at 0800 UTC
on the 10th, but it is not known if this wind was a gust or a MSW. The
MSLP was 1000 mb at 1200 UTC with a south-southeast wind of 15 kts. The
most reliable information from Salalah indicates a peak MSW of roughly
29 kts from the east-northeast at 0500 UTC on the 10th. A MSLP of 999 mb
was recorded concurrently. Less reliable sources reported a MSLP as high
as 1013.4 mb at 0500 UTC, even though the MSW estimates nearly match. In
addition, this source recorded gusts of 41 kts at 0500 UTC; the MSLP was
1007.3 mb at 1100 UTC with a MSW of only 14 kts. Though conflicting,
both sets of data may be useful.
The southeast coast of the Arabian Peninsula is normally a very
arid region. Muscat, on the northern coast of the Peninsula receives
an average of 100 mm of rain a year while Aden, on the southern coast,
records a paltry 23 mm of rain per year. This region was hammered by
TC-01A's downpours. Julian Heming, from the UK Meteorological Office,
provided the following rainfall totals:
Thumrait 23.8 mm
Salalah 58.6 mm - 66.8 mm
Qairoon Hairiti 250.6 mm
There is a minor question as to whether TC-01A's intensity was under-
estimated at landfall. Meteorologist Julian Heming stated that banana
and palm trees were uprooted in Salalah, where gusts to 57 kts were
reported. Dave Membery states that a forecaster at Seeb reported gusts
exceeding 60 kts. It is unlikely, however, that TC-01A was significantly
more intense than 40 kts at landfall, given its poor organization. A
gust factor of 1.6, standard for overland tropical cyclones, reduces a
60-kt gust to a 38-kt MSW, which agrees well with the current landfall
intensity estimate. Nevertheless, the damage reports might give skeptics
pause.
D. Damage and Casualties
------------------------
Damage in Oman was substantial from Tropical Cyclone 01A. The Oman
Times reported it to be the first storm to hit Salalah in nearly twenty
years, resulting in "tremendous damage to life and property". There was
reportedly substantial damage in the rural areas of Oman, with rooftops
blown away, broken power and communications grids, and livestock losses.
Indeed, some places were described as looking like a "war torn area".
There were at least two known deaths and five missing as of the time
of this writing.
TROPICAL CYCLONE
(TC-02B)
10 - 12 May
------------------------------------
The tropical disturbance that become Tropical Cyclone 02B was first
noted west of the island of Sumatra on 7 May. It was initially little
more than cyclic convection that flared up beneath an upper-level ridge.
The disturbance tracked slowly northward with no significant development
until early on the 9th, when an ill-defined LLCC formed. Its organi-
zation improved markedly late that day, warranting the issue of a TCFA
at 1030 UTC. Quikscat data and Dvorak analyses supported the issue of
warnings on Tropical Cyclone 02B at 1200 UTC on 10 May while located
125 nm southeast of Port Blair in the Andaman Islands.
The cyclone's convection was initially mercurial, and "pulsed" over
time, but become more persistent on the 11th. It reached its peak MSW
of 45 kts at 0600 UTC on 11 May when located 250 nm south of Yangan
(formerly Rangoon), Myanmar. TC-02B maintained this intensity until near
the time of landfall, though not without further convective cycles. The
storm continued its slow, roughly northward track under the influence of
a mid-level ridge to its east.
Tropical Cyclone 02B accelerated unexpectedly and turned north-
northeastward--landfall was at roughly 2300 UTC on 11 May just east of
Yangan with the MSW estimated at 35 kts. According to the JTWC, Yangan
experienced gusts of 25 kts at this time. The storm quickly weakened
to a depression, and the last warning was issued at 0600 UTC on 12 May,
placing the center about 95 nm north-northeast of Yangan.
No casualties or deaths are known to have resulted from this system.
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for May: 1 tropical cyclone
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Southwest Indian Ocean tropical cyclones are the warnings issued by
the Tropical Cyclone Warning Centre on La Reunion Island, part of
Meteo France (MFR), and the Regional Specialised Meteorological Centre
for the basin. However, tropical cyclones in this region are named
by the sub-regional warning centres on Mauritius and Madagascar with
longitude 55E being the demarcation line between their respective
areas of warning responsibility. The La Reunion centre only advises
these agencies regarding the intensity of tropical systems. References
to sustained winds imply a 10-minute averaging period unless otherwise
stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from MFR's coordinates by usually
40-50 nm or more. The JTWC warnings are also the source of the
1-minute average maximum sustained wind values included in the
tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Southwest Indian Ocean Tropical Activity for May
------------------------------------------------
After a quiet month, the Southwest Indian Ocean produced its final
tropical cyclone of the active 2001-2002 season. Kesiny began developing
late in April as a MJO impulse moved eastward across the Indian Ocean.
This impulse was responsible for the formation of four tropical cyclones
across the Indian Ocean during the first two weeks of May. Tropical
Cyclone Kesiny formed as a twin with TC-02A in the Arabian Sea. The
storm moved west-southwestward and eventually struck the northern tip
of Madagascar as a minimal tropical cyclone (i.e., hurricane) where it
was quite destructive.
TROPICAL CYCLONE KESINY
(MFR 14 / TC-23S)
30 April - 11 May
-------------------------------------------
A. Storm Origins
----------------
The origins of late-season Tropical Cyclone Kesiny lay within an area
of convection which developed on 30 April approximately 175 nm west-
northwest of Diego Garcia. Water vapor imagery showed pronounced out-
flow over the broad LLCC which was associated with a near-equatorial
trough. The deeper convection was located well south of the center.
The disturbance was relocated farther to the west on 1 May, but then
commenced a slow drift to the east-southeast. JTWC issued a TCFA for
the system at 2100 UTC on 2 May based upon improving convective organ-
ization. The center of the broad LLCC was then located approximately
450 nm east-southeast of the Seychelles Islands. The TCFA was re-issued
at 03/0600 UTC, placing the center about 400 nm west-southwest of Diego
Garcia. Also at 0600 UTC, MFR upgraded the system to tropical depression
status. The LLCC had tracked farther eastward than anticipated under the
steering influence of strong equatorial westerlies. Shortly afterward,
around 0900 UTC, JTWC issued their first warning on TC-23S with an
initial warning intensity of 30 kts.
JTWC upped the MSW (1-min avg) to 35 kts at 1800 UTC based on Quik-
Scat data. The depression at this time was moving southward at 6 kts,
but a mid-level ridge south of Diego Garcia was forecast to build,
creating a more southwesterly steering influence. A QuikScat pass
around 0600 UTC on 4 May reported 40-kt winds, although the LLCC was
still east of the deep convection. Based on the QuikScat data, JTWC
increased the 1-min avg MSW to 40 kts while Mauritius upgraded the system
to Tropical Storm Kesiny with 35-kt winds (10-min avg). Kesiny was
located at the time roughly 400 nm west-southwest of Diego Garcia.
B. Track and Intensity History
------------------------------
Tropical Storm Kesiny gradually increased in intensity--by 0600 UTC
on 5 May both MFR and JTWC had increased their respective MSW estimates
to 45 kts even though the majority of the deep convection remained
decoupled to the west of the center. Kesiny was moving westward at
8 kts and was forecast to move generally to the west-southwest, guided
by a mid-level ridge south of the storm. Winds had reached 55 kts
(from both warning centers) by 1800 UTC. Outflow was improving over the
northwest quadrant and the vortex center had moved under the deep con-
vection. A strengthening HIGH southeast of Madagascar was forecast to
continue steering the storm on a west-southwesterly track.
By 0600 UTC on 6 May Kesiny had reached a position approximately
675 nm east-northeast of the northern tip of Madagascar, or about 475 nm
southeast of the Seychelles. Satellite CI estimates were 55 to 60 kts,
but a recent QuikScat pass had indicated winds of 65-70 kts in the
southern semicircle and earlier microwave imagery had revealed a possible
banding eye feature. MFR increased the intensity to 60 kts while JTWC
upped the 1-min avg MSW estimate to 65 kts. The intensity estimates
were the same at 1800 UTC when Kesiny was located about 600 nm east of
Madagascar. The storm was moving west-southwestward at 4 kts, and
animated water vapor imagery indicated improving equatorward outflow and
a weak poleward outflow channel.
The intensification trend, however, was reversed on 7 May and Kesiny
weakened significantly, apparently due to weakening outflow in both
channels. MFR lowered the MSW to 55 kts at 07/0000 UTC, and to 50 kts
at 0600 UTC. JTWC dropped the 1-min avg MSW to 55 kts at 0600 UTC,
and by 1800 UTC both centers were reporting the intensity at 45 kts.
Kesiny at the time was located about 500 nm east of the northern tip of
Madagascar, moving toward the west-southwest at 6 kts. Convection in
all quadrants was weakening in the presence of poor outflow conditions.
Kesiny's intensity reached a local minimum around 0600 UTC on the 8th
when it was centered about 400 nm south of the Seychelles, or approxi-
mately 350 nm east of Madagascar's northern tip. Both MFR and JTWC had
lowered their respective MSW estimates to 40 kts, based on CI estimates
of 35 and 45 kts. The LLCC was partially-exposed, but a resurgence of
convection was seen occurring in the western semicircle. Kesiny was
forecast to continue tracking west-southwestward without significant
strengthening.
However, the storm's intensity began to increase again as the 8th
progressed. MFR upped the intensity to 45 kts at 1200 UTC and to 50 kts
six hours later, while JTWC bumped the 1-min avg MSW estimate back to
45 kts at 1800 UTC. The storm's outflow was improving and Kesiny
responded by intensifying once more. The strengthening storm was located
at 1800 UTC about 230 nm east of the northern tip of Madagascar, moving
westward at 11 kts. By 0600 UTC on 9 May both MFR and JTWC had increased
their respective MSW estimates to 60 kts, based on CI values of 55 and
65 kts. The storm was only 90 nm east of northern Madagascar, and recent
visible satellite imagery had revealed a developing banding eye feature.
The system lay under good diffluent flow which had aided intensification.
MFR upgraded Kesiny to tropical cyclone (hurricane) status at 1200 UTC
with the MSW estimated at 70 kts. The cyclone was almost on the coast-
line of northeastern Madagascar about 75 nm southeast of the island's
northern tip. By 1800 UTC the storm had crossed the northern extremity
of the island and was just inland near the west coast. The banding eye
feature had disappeared and CI estimates were 45 and 55 kts. JTWC
dropped their MSW estimate to 55 kts (1-min avg) while MFR reported the
intensity at 45 kts (10-min avg). The center was back over the waters
of the Mozambique Channel at 10/0000 UTC, and by 0600 UTC had moved
approximately 100 nm offshore. The MSW estimates from MFR and JTWC were
35 and 40 kts, respectively, and the much-weakened storm was moving
west-southwestward at 10 kts.
Instead of undergoing a modest re-intensification over the Channel as
had initially been forecast, Kesiny continued to weaken and turned south-
ward, keeping the center near the coastline of northwestern Madagascar.
MFR downgraded Kesiny to a tropical depression at 1200 UTC and JTWC
followed suit at 1800 UTC. The system was located about 50 nm northeast
of Mahajanga, moving south-southwestward at 8 kts. The winds had dropped
to 25 kts by 11/0600 UTC and MFR issued their final bulletin on Kesiny.
The depression had made landfall at 10/1830 UTC about 40 nm northeast of
Mahajanga and was tracking southward at only 2 kts. JTWC issued their
final warning on Kesiny at 11/1800 UTC, placing the center inland to the
northeast of Mahajanga. The system was forecast to drift southward and
dissipate over land.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
Maximum sustained winds as estimated by La Reunion and JTWC were in
very good agreement for the duration of Tropical Cyclone Kesiny, being
within 10 kts of each other after conversion to the same time averaging
period. Indeed most of the time they were within 5 kts of each other.
JTWC's warnings did not reflect the peak intensity of 70 kts assigned
by MFR just before Kesiny made landfall in Madagascar, but this was due
to the 12-hour interval between JTWC's warnings. At 0600 UTC on 9 May
both warning centers estimated 60 kts--by the time of the next JTWC
warning at 1800 UTC, the storm had made landfall and was weakening.
D. Damage and Casualties
------------------------
Even though not as intense as some destructive cyclones which have
struck Madagascar, Kesiny had precipitation power. Torrential rains
led to severe and widespread flooding and landslides. Differing numbers
of fatalities were reported in various press releases, but it appears
that at least 20 and possibly as many as 33 persons died, primarily
due to drowning and by being buried in landslides. An additional 180
were reported as missing--many of these will possibly be added to the
fatality count--and over 1200 persons were injured. A report of the
Office for the Coordination of Humanitarian Affairs (OCHA) stated that
average winds of 60-65 kts with gusts to 98 kts were recorded, but the
particulars of time and location were not given. Over 520,000 persons
were adversely affected by the cyclone and approximately 5000 were left
homeless.
The port city of Toamasina was hard-hit. Much of the city was flooded
and all roads leading into the town were cut-off--the only access was by
sea or air. Residents were without electricity and fresh water for
several days. Some rivers in the region reportedly rose from 12 to 18
metres above their normal levels. In northern Madagascar the rice, bean
and maize crops, traditionally harvested between early May and mid-June,
were hard-hit with 50 to 75% of the crops destroyed. More information
about the effects of Tropical Cyclone Kesiny can be obtained at the
following URL: http://www.reliefweb.int/w/rwb.nsf> .
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for May: 1 tropical cyclone of gale intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Northwest Australia/Southeast Indian Ocean tropical cyclones are
the warnings and advices issued by the Tropical Cyclone Warning
Centres at Perth, Western Australia, and Darwin, Northern Territory.
References to sustained winds imply a 10-minute averaging period
unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Australian centres' coor-
dinates by usually 40-50 nm or more. The JTWC warnings are also the
source of the 1-minute average maximum sustained wind values included
in the tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Northwest Australia/Southeast Indian Ocean
Tropical Activity for May
------------------------------------------
An impulse of the MJO left the African coast at the end of April and
migrated eastward across the Indian Ocean. During the first week it was
responsible for spawning a cross-equatorial pair of cyclones: Kesiny
in the Southwest Indian Ocean and TC-02A in the Arabian Sea. As the
enhanced convection reached the eastern Indian Ocean, another pair of
systems formed--making a set of what could be termed tropical cyclone
"quadruplets". TC-02B formed in the Bay of Bengal on the 10th while
Tropical Cyclone Errol was named on the 9th well north of Cocos Island.
Errol meandered about for several days but never intensified beyond
minimal gale intensity. At 1200 UTC on 10 May, all four Indian Ocean
systems were of gale force, based on JTWC's warnings, although Kesiny
was rapidly weakening.
TROPICAL CYCLONE ERROL
(TC-24S)
8 - 16 May
------------------------------------------
A. Storm Origins
----------------
Tropical Cyclone Errol developed as the southern member of a pair
of cyclone twins, the Northern Hemisphere member being Tropical Cyclone
02B in the eastern Bay of Bengal. An area of convection developed on
8 May approximately 80 nm west of Sumatra with cycling scattered con-
vection which persisted for more than 12 hours. A 200-mb analysis
indicated that the disturbance was situated in the divergent region of
an upper-level ridge anchored over Thailand. The suspicious area was
relocated farther south at 1800 UTC with no indication of a significant
LLCC. Early on the 9th the disturbance began to undergo rather rapid
organization. At 0400 UTC the Perth TCWC upgraded the system to Tropical
Cyclone Errol with 35-kt winds while at 0600 UTC JTWC issued a TCFA for
Errol. Deep convection had increased, although it was sheared west of
the LLCC, and a recent QuikScat pass had indicated 30-kt winds east of
the center. Satellite intensity estimates were 25-30 kts, and a 200-mb
analysis indicated that the system was equatorward of the ridge axis
in a region of moderate easterly vertical shear.
B. Track and Intensity History
------------------------------
JTWC issued their first warning on Errol at 09/1800 UTC with the
center located approximately 300 nm north-northwest of Cocos Island.
JTWC estimated the MSW (1-min avg) at 30 kts while Perth maintained the
10-min avg MSW at 35 kts. A recent QuikScat pass had indicated winds
to 35 kts west of the LLCC. Errol was forecast to track westward under
the steering influence of a low to mid-level ridge, currently south-
southwest of the cyclone but forecast to slide eastward. At 0600 UTC
on 10 May Errol's center was relocated eastward to a position about
360 nm north of Cocos Island. JTWC increased their 1-min avg MSW
to 35 kts based on continued QuikScat winds to 35 kts west of the
exposed LLCC. During the 10th Errol remained quasi-stationary, perhaps
drifting to the west slightly. The intensity remained static with deep
convection over the center cycling in intensity.
By 0400 UTC on 11 May CI estimates had increased a bit to 45 kts.
JTWC upped their 1-min avg MSW estimate to 45 kts while Perth maintained
the intensity at 35 kts. Errol continued drifting westward and by 1800
UTC had reached a point approximately 350 nm north-northwest of Cocos
Island. A 37 GHz TRMM image at 11/1602 UTC suggested that a weak
secondary circulation lay directly west of Errol. Current intensity
estimates had dropped a bit by early on the 12th and JTWC lowered their
reported MSW to 40 kts at 12/0600 UTC. At 1800 UTC the center of Trop-
ical Cyclone Errol was located roughly 300 nm north-northwest of Cocos
Island, moving south-southwestward at 6 kts. A recent microwave image
indicated that the deep convection was displaced to the southwest of the
LLCC. Errol was forecast to track slowly southwestward toward a weak-
ness in the subtropical ridge.
At 0400 UTC on 13 May Perth made a significant relocation of Errol's
center southward and eastward--to a position roughly 250 nm north-
northwest of Cocos Island. The system was moving south-southeastward
at 6 kts and deep convection was sheared 45 nm to the south-southwest of
the LLCC. Satellite intensity estimates were still 35 and 45 kts, but
both Perth and JTWC reported the intensity at 35 kts. At 1800 UTC the
partially-exposed center of Errol was approximately 200 nm north-
northwest of Cocos Island and appeared to be weakening. At 2100 UTC
Perth cancelled the gale warning and issued their final warning on the
cyclone. JTWC issued their final warning at 14/0600 UTC, placing the
center 130 nm north-northwest of Cocos Island, moving southeastward at
7 kts with maximum winds of only 25 kts. The residual LOW continued
moving southeastward and was last mentioned in a STWO from Perth at
0400 UTC on the 16th when it was located about 500 nm southwest of
Christmas Island.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
Intensity estimates between Perth and JTWC agreed very well for Errol.
During the time the cyclone was in warning status, Perth estimated the
maximum 10-min avg wind at 35 kts. For most of Errol's history, JTWC
also estimated the MSW (1-min avg) at 35 kts, but did raise the MSW to
45 kts on the 11th. This would equate to a 10-min avg MSW of 40 kts,
which is only 5 kts higher than Perth's estimate.
D. Damage and Casualties
------------------------
No damage or casualties are known to have resulted from Tropical
Cyclone Errol.
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for May: 1 tropical cyclone of gale intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Northeast Australia/Coral Sea tropical cyclones are the warnings
and advices issued by the Tropical Cyclone Warning Centres at
Brisbane, Queensland, and Darwin, Northern Territory, and on very
infrequent occasions, by the centre at Port Moresby, Papua New
Guinea. References to sustained winds imply a 10-minute averaging
period unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Australian centres' coor-
dinates by usually 40-50 nm or more. The JTWC warnings are also the
source of the 1-minute average maximum sustained wind values included
in the tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Northeast Australia/Coral Sea
Tropical Activity for May
-----------------------------
The TCWC at Brisbane once issued tropical cyclone warnings for the
entire tropical region lying east of Darwin's AOR to longitude 160E.
However, when the former Australian territory of Papua New Guinea was
granted independence in 1973, that nation established a meteorological
service and Brisbane turned over tropical cyclone warning responsibility
to them for a limited region immediately surrounding Papua New Guinea
and extending eastward to 160E generally north of latitude 10S. Very
few tropical cyclones form and reach gale intensity in this region.
Tropical Cyclone Upia in May, 2002, was the first system named by the
Papua New Guinea TCWC at Port Moresby since Tropical Cyclone Adel in
May, 1993. Upia remained a fairly weak cyclone and did not significantly
affect any islands in the area.
TROPICAL CYCLONE UPIA
(TC-25P)
25 - 29 May
-----------------------------------------
A. Storm Origins
----------------
Tropical Cyclone Upia was the first tropical cyclone to develop within
the limited AOR of the TCWC at Port Moresby, Papua New Guinea, in nine
years. The last system forming in this region was Tropical Cyclone Adel
in May, 1993. (A description of Adel can be found in the tropical
cyclone summary for December, 2001.) On 23 May an area of convection
developed approximately 120 nm north of the Solomon Islands. A well-
defined mid-level vortex was present but the LLCC was broad and difficult
to locate. QuikScat data indicated maximum winds of 20-25 kts while a
200-mb analysis revealed that the disturbance was located equatorward of
a ridge axis in a region of good diffluence and weak vertical shear.
JTWC assigned a fair development potential to the disturbance.
At 0600 UTC on 24 May the partially-exposed broad LLCC was located
approximately 75 nm north of the Solomon Islands. Deep convection was
cycling but was increasing in areal extent near the LLCC. An area of
deep convection was also persisting southwest of the center. JTWC issued
a TCFA at 25/0130 UTC, placing the center about 100 nm southwest of
Bougainville. A developing banding feature was wrapping in toward the
LLCC from the southeast, and the MSW was estimated at 25-30 kts. The
first warning from JTWC was issued at 1200 UTC on the 25th with the MSW
(1-min avg) estimated at 35 kts. A recent SSM/I pass had depicted deep
convection beginning to build over the LLCC with a convective band
developing in the southeast quadrant. By 1800 UTC the center of TC-25P
was located approximately 165 nm southwest of Bougainville, moving south-
westward at 4 kts. Also at 1800 UTC, the Port Moresby warning center
issued the first advisory on Tropical Cyclone Upia, assigning a 10-min
avg MSW of 40 kts.
B. Track and Intensity History
------------------------------
At 0000 UTC on 26 May Upia's center was located approximately 165 nm
southwest of Bougainville. Moderate upper-level northeasterlies were
hampering outflow over the northern half of the storm. Strengthening
low-level tropical easterlies appeared to be offsetting the low-level
equatorial westerlies, thereby imparting a temporary southwesterly drift
to the system. By 0600 UTC Upia was moving slowly south-southeastward
at 4 kts, influenced by a low to mid-level subtropical ridge to the
east. By 1800 UTC the cyclone was moving southward at 4 kts with the
respective MSW estimates from Port Moresby and JTWC being 40 and 35 kts,
based on CI estimates of 35 and 45 kts. Some warming of cloud tops had
been noted along with a decrease in the areal coverage of deep convec-
tion. Water vapor imagery and a 200-mb analysis indicated that Upia had
slipped poleward of the subtropical ridge axis.
By 27/0000 UTC the weak tropical cyclone had become quasi-stationary.
Multi-spectral imagery at 26/2030 UTC had depicted a fully-exposed LLCC
about 40 nm north of the previous warning position. Some recent pictures
revealed that convection had started to rebuild over the center; however,
apparently as soon as new convection formed it was sheared to the south
by upper-level northerlies overlying the system. At 0600 UTC Upia's
fully-exposed center was drifting northward with the nearest convection
located 65 nm to the south. By 0000 UTC on 28 May the cyclone was once
more drifting south-southeastward, being located approximately 180 nm
south-southwest of Bougainville. The LLCC was located just north of
some new deep convection which had redeveloped during the previous few
hours. Port Moresby upped the intensity to 50 kts while JTWC's 1-min
avg MSW remained at 35 kts.
At 28/0600 UTC JTWC issued their final warning on Tropical Cyclone
Upia. The intensity was lowered to 30 kts based on CI estimates of
30 kts and a recent QuikScat pass which had indicated winds of 30 kts
near the center. At the same time Port Moresby decreased their MSW
estimate to 45 kts. The final warning on Upia from Port Moresby (that
I have available) was issued at 1800 UTC, further reducing the winds to
35 kts. The system subsequently moved south of their AOR and into Bris-
bane's region of warning responsibility. At 29/0600 UTC Brisbane issued
a warning downgrading Upia to an ex-tropical cyclone. The system had
merged with a large tropical trough with winds still forecast to reach
near gale force in the vicinity of the LOW. The final bulletin on the
former tropical cyclone, at 1800 UTC, placed the LOW approximately 250 nm
west-southwest of Honiara on Guadalcanal.
C. Comparisons Between JTWC and Other Centers
---------------------------------------------
Intensity estimates from Port Moresby and Brisbane tended to be some-
what higher than JTWC's estimates. JTWC never reported the 1-min avg
MSW for Upia any higher than 35 kts. Port Moresby estimated the MSW
(presumably 10-min avg) at 40 kts (equivalent to a 1-min avg MSW of
45 kts) for most of the cyclone's history, increasing to 50 kts at
28/0000 UTC with an estimated central pressure of 995 mb. This would be
the equivalent of a 1-min avg MSW of 60 kts--considerably more intense
than the 35 kts estimated by JTWC. On the next warning at 28/0600 UTC,
JTWC reduced the 1-min avg MSW to 30 kts while Port Moresby lowered the
10-min avg MSW estimate to 45 kts, and further to 35 kts at 1800 UTC.
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Cyclone
Upia have been received.
E. Additional Discussion
------------------------
I'd especially like to thank Jeff Callaghan of the Brisbane TCWC for
alerting me to the development of Upia and for passing along some of
Port Moresby's warnings. It seems appropriate to conclude this discus-
sion of Tropical Cyclone Upia with the text of an e-mail from Jeff: "We
here in Brisbane would like to acknowledge the great work the PNG cyclone
forecasters did during Upia. They don't get many tropical cyclones in
their area of responsibility, but despite this they retain great interest
in these systems and during the event made excellent use of new web-based
technologies such as Jeff Hawkin's SSMI/TRMM site, Chris Velden's CIMSS
site and the various QuikScat sites. This surely is an example of how
the web can help forecasters in countries like PNG."
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for May: No tropical cyclones
*************************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the July, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
*************************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
in the following manner:
(a) FTP to: hrd-type42.nhc.noaa.gov [140.90.176.206]
(b) Login as: anonymous
(c) For a password use your e-mail address
(d) Go to "data" subdirectory (Type: cd data)
(e) Set file type to ASCII (Type: ascii)
(f) Transfer file (Type: get remote_file_name local_file_name )
(The files will be named with an obvious nomenclature--using
May as an example: may02.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: may02.sum, for
example.
Back issues can also be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua and Michael Pitt):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.ph> OR http://66.40.4.61>
http://mpitthurricane.com>
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
AND
John Wallace (Northeast Pacific and North Indian Ocean)
E-mail: [email protected]
*************************************************************************
*************************************************************************
|
Document: summ0205.htm
Updated: 27th December 2006 |
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