MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
NOVEMBER, 2004
First Installment
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
SPECIAL NOTE: The November summary will be issued in two installments.
This first one covers the North Indian and Southwest Indian Ocean basins
and contains the Feature of the Month. The second installment will cover
the Atlantic and Northwest Pacific basins.
*************************************************************************
NOVEMBER HIGHLIGHTS
--> Philippines experience deadly visits from tropical systems
--> Surprise Atlantic storm forms on last day of official season
--> Two storms--one intense--form in Southwest Indian Ocean
--> Arabian Sea cyclone forms almost on equator
*************************************************************************
***** Feature of the Month for November *****
A REVIEW OF THE 2003-2004 TROPICAL CYCLONE SEASON
FOR THE SOUTHERN HEMISPHERE
Following is a tabular summary of all the tropical depressions
and tropical cyclones which occurred in the Southern Hemisphere
between 1 July 2003 and 30 June 2004 as reported in the Monthly
Global Tropical Cyclone Summaries prepared by the author.
(1) Number - this is the sequential cyclone number assigned by JTWC
in Hawaii.
(2) Name - the name (if any) assigned by the responsible Tropical
Cyclone Warning Centre. For systems in the South Indian Ocean
west of 90E and in the Southwest Pacific east of 160E which were
unnamed, the alphanumeric designator applied by La Reunion or
Fiji, respectively, is given in this column.
(3) Dates - range of dates for which tracking information for the
cyclone is available in the Global Tropical Cyclone Tracks files
prepared by the author. The dates given in most cases refer to
the time the system was in warning status and generally do not
include the pre-depression stages of the disturbance.
(4) Pressure - Lowest central pressure (either estimated or recorded)
during the lifetime of the cyclone. An asterisk (*) following
the pressure indicates the reading was an actual measured
pressure. Central pressure is given in millibars, which is
numerically equivalent to hectopascals.
(5) MSW 1-min avg - maximum 1-minute average sustained windspeed in
knots as assigned by JTWC. An asterisk (*) following the MSW
indicates that it was an actual measured value.
(6) MSW 10-min avg - maximum 10-minute average sustained windspeed
in knots as assigned by the responsible Tropical Cyclone Warning
Centre. An asterisk (*) following the MSW indicates that it was
an actual measured value.
(7) Basins - tropical cyclone basins where the cyclone tracked during
its life:
SWI - Southwest Indian Ocean - West of 90E
AUW - Northwest Australia/Southeast Indian Ocean - 90E to 135E
AUE - Northeast Australia/Coral Sea - 135E to 160E
SPA - South Pacific Ocean - East of 160E
SAT - South Atlantic Ocean
A number in parentheses (e.g. (1) ) following an entry refers to
a note following the entries for the given basin. A separate table
is given for each of the four Southern Hemisphere basins.
Abbreviations for Tropical Cyclone Warning Centres:
JTWC - Joint Typhoon Warning Center, formerly on Guam, now at
Pearl Harbor, Hawaii
MFR - Meteo France Reunion (RSMC La Reunion)
RSMC - Regional Specialised Meteorological Centre
************************************************************************
SOUTH ATLANTIC OCEAN
JTWC NAME DATES CENT MSW MSW BASIN
NUM PRS 1-MIN 10-MIN
(mb) (kts) (kts)
------------------------------------------------------------------------
01T Catarina 19-28 Mar --- 85 -- SAT (1)
NOTES:
(1) The number "01T" was unofficially assigned by Julian Heming of the
UK Meteorological Office. The name "Catarina" was apparently used
by the Brazilian news media. The track included in the March
tropical cyclone tracks file was supplied by Roger Edson. Prior
to Catarina, back in January, another tropical cyclone of tropical
depression or minimal tropical storm intensity occurred just off the
tropical Brazilian coastline. No track was available for this
system.
************************************************************************
SOUTHWEST INDIAN OCEAN
JTWC NAME DATES CENT MSW MSW BASIN
NUM PRS 1-MIN 10-MIN
(mb) (kts) (kts)
------------------------------------------------------------------------
01S Abaimba 29 Sep-04 Oct 990 50 45 SWI
02S Beni 09-22 Nov 935 105 100 SWI
03S Cela 05-21 Dec 968 65 65 SWI
06S Darius 29 Dec-04 Jan 976 65 55 SWI
09S Elita 26 Jan-12 Feb 974 65 60 SWI
10S Frank 27 Jan-07 Feb 925 125 105 SWI
16S Gafilo 02-15 Mar 895 140 125 SWI
21S (MFR-11) 13-28 Mar 1002 30 25 AUW/SWI
23S Juba 05-15 May 980 65 55 SWI
************************************************************************
NORTHWEST AUSTRALIA / SOUTHEAST INDIAN OCEAN
JTWC NAME DATES CENT MSW MSW BASIN
NUM PRS 1-MIN 10-MIN
(mb) (kts) (kts)
------------------------------------------------------------------------
04S Jana 07-12 Dec 960 80 75 AUW
05P Debbie 17-21 Dec 970 65 65 AUE/AUW
08S Ken 01-06 Jan 992 35 40 AUW
11S Linda 28 Jan-01 Feb 978 45 55 SWI/AUW
--- ----- 08-12 Feb 994 -- 30 AUW
14S Monty 26 Feb-02 Mar 935 110 95 AUW
17S Nicky-Helma 08-13 Mar 972 70 60 AUW/SWI
18S Fay 14-28 Mar 910 120 115 AUW
20S Oscar-Itseng 20-28 Mar 935 110 95 AUW/SWI
************************************************************************
NORTHEAST AUSTRALIA / CORAL SEA
JTWC NAME DATES CENT MSW MSW BASIN
NUM PRS 1-MIN 10-MIN
(mb) (kts) (kts)
------------------------------------------------------------------------
--- ----- 30 Dec-01 Jan 996 -- 35 AUE (1)
12P Fritz 08-12 Feb 985 35 45 AUE
15P Evan 29 Feb-06 Mar 994 35 40 AUE/AUW
--- ----- 02-05 Mar 994 -- 55 AUE (2)
19P Grace 18-24 Mar 985 35 50 AUE/SPA
--- (13F) 10-20 Apr 1002 -- 30 AUE/SPA
NOTES:
(1) System was described in warnings from Brisbane as a monsoon LOW.
The center was actually east of 160E during much of its life.
(2) System was not a true tropical LOW but more hybrid in nature.
************************************************************************
SOUTH PACIFIC OCEAN
JTWC NAME DATES CENT MSW MSW BASIN
NUM PRS 1-MIN 10-MIN
(mb) (kts) (kts)
------------------------------------------------------------------------
07P Heta 28 Dec-11 Jan 915 140 115 SPA
13P Ivy 21-29 Feb 935 110 90 SPA
--- (06F) 20-22 Mar 994 -- 25 SPA (1)
--- (08F) 30 Mar-01 Apr 1002 -- 40 SPA (1)
--- (09F) 01-03 Apr 1000 -- 30 SPA (1)
22P (10F) 04-09 Apr 995 35 32 SPA
--- (12F) 07-12 Apr 1002 -- 25 SPA
--- ----- 02-03 May 998 -- -- SPA (2)
NOTES:
(1) Gales were associated with these systems but were well-removed from
the center.
(2) No maximum wind estimates were given in the Fiji summaries for this
system, and it likely was not purely tropical but rather hybrid in
nature. Peripheral gales of up to 40 kts were forecast for this
system.
************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for November: 1 tropical storm
NOTE!!! The Atlantic basin will be covered in the second installment
of the November summary.
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for November: No tropical cyclones
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for November: 3 tropical depressions **
1 tropical storm ++
1 typhoon
1 super typhoon
** - two of these were classified as tropical depressions by JMA only;
another by JMA and PAGASA
++ - classified as a tropical storm by JMA only, but as a tropical
depression by PAGASA also
NOTE!!! The Northwest Pacific basin will be covered in the second
installment of the November summary.
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for November: 1 deep depression **
1 severe cyclonic storm ++
** - this system classified as a tropical storm by JTWC
++ - this system classified as a hurricane by JTWC
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.
North Indian Ocean Tropical Activity for November
-------------------------------------------------
Two tropical cyclones came to life in the North Indian Ocean during
the month of November, both in the Arabian Sea. The first one was
classified as a minimal tropical storm by JTWC, but only as a deep
depression by IMD. Tropical Cyclone 04A formed early in the month in
the central Arabian Sea and moved generally in the direction of the
Arabian Peninsula, later moving southwestward as it weakened and
dissipated off the coast of Somalia. Late in the month Cyclonic Storm
Agni formed at an extremely low latitude in the southern Arabian Sea,
only 42 nm north of the equator. Furthermore, before the tropical storm
developed, the parent circulation had drifted southwestward to a point
just south of the equator and then moved back into the Northern
Hemisphere while maintaining its counterclockwise circulation. Short
reports on both these systems follow.
TROPICAL CYCLONE
(TC-04A)
4 - 7 November
------------------------------------
A STWO issued by JTWC at 1800 UTC on 31 October noted that an area
of convection had developed and persisted approximately 750 nm west
of Colombo, Sri Lanka. A 31/0106 UTC QuikScat pass had revealed the
existence of a LLCC around which convection was beginning to organize,
and upper-level conditions were favorable for further development with
good diffluence and low vertical shear. The potential for development
was upgraded to fair at 1300 UTC on 1 November as deep convection had
continued to consolidate around the LLCC. A ship observation around
01/0600 UTC had reported maximum winds of only 10-15 kts, but in light
of the increasing organization the MSW was estimated to have increased
to 20-25 kts. At 02/1800 UTC the disturbance had moved westward to
a point almost 900 nm west-northwest of Colombo and deep convection was
continuing to cycle near the LLCC.
At 0700 UTC on 4 November the system was located almost 500 nm south-
west of Mumbai (Bombay), India, and the deep convection was becoming
more wrapped around the LLCC. Animated water vapor imagery showed an
increase in poleward outflow, and an upper-level analysis indicated
that the LLCC was located in an environment of low to moderate vertical
shear with favorable divergence aloft. Maximum winds were estimated
at 25-30 kts, and the potential for development was upgraded to good
with a TCFA being issued at this time. The first JTWC warning on
Tropical Cyclone 04A was issued at 1200 UTC on the 4th, placing the
center approximately 500 nm southwest of Mumbai. The initial warning
intensity was set at 35 kts.
Over the next couple of days TC-04A moved on a course slightly north
of due west. The peak intensity of 40 kts was reached at 05/0600 UTC,
and again for a 12-hour period beginning at 06/0000 UTC, based on
satellite CI estimates of 35 and 45 kts. The system was in an environ-
ment of weak vertical shear and poleward outflow, but deep convection
remained confined to the eastern semicircle. The MSW was decreased to
35 kts at 1200 UTC on the 6th as satellite imagery revealed a fully-
exposed LLCC located approximately 120 nm to the southwest of the
remaining convection. After 07/0000 UTC, TC-04A began to move on
a southwesterly track as it weakened. Deep convection had dissipated
by 07/1200 UTC due to the entrainment of dry, continental air and the
MSW was dropped to 25 kts. The final JTWC warning at 1800 UTC placed
the still well-defined LLCC about 150 nm east of Socotra Island, or
about 280 nm east-northeast of Cape Guardafui, Somalia. (This system
was not treated as a cyclonic storm by IMD.)
TC-04A seemed to stage a weak attempt at a comeback. A QuikScat
chart at 0724 UTC on 9 November shows a circulation off the coast of
Somalia with some possible rain-contaminated vectors exceeding 50 kts,
and a visible image at 09/0500 UTC depicts a flare-up of convection
associated with the system.
No damage or casualties are known to have resulted from this rather
weak marine cyclone.
(Report written by Gary Padgett)
SEVERE CYCLONIC STORM AGNI
(ARB0403 / TC-05A)
28 November - 3 December
----------------------------------------------
Agni: contributed by India, means 'fire'
A. Storm Origins
----------------
The origins of Agni are in a sense more exciting than the cyclonic
storm stage which followed. As early as 19 November an area of
convection developed and persisted at an unusually low latitude (2.7N)
about 445 nm east-southeast of Colombo, Sri Lanka. Animated multi-
spectral imagery and an 18/1235 UTC QuikScat pass showed that convection
was beginning to consolidate around a well-defined LLCC. Concurrently,
an upper-level analysis indicated that the region was under moderate
vertical shear but also in a region of favorable divergence. Maximum
winds were estimated at 20 kts. Over the next few days the rather
broad LLCC drifted westward, passing approximately 250 nm south of
Colombo on the 21st. Deep convection seemed to be increasing on the
22nd so the development potential was upgraded to fair. JTWC issued a
TCFA for the system at 2200 UTC on 22 November, placing the center
about 255 nm southwest of Colombo and estimating the maximum winds at
25-30 kts. However, 24 hours later the convection had decreased and
had become cyclic, so the TCFA was cancelled and the potential for
development downgraded to poor. The disturbance was written off as a
candidate for tropical cyclone development on the 24th.
Another area of convection had developed by 1800 UTC on 26 November
about 560 nm southwest of Colombo, or only 90 nm north of the equator.
This area of disturbed weather was likely a continuation of the earlier
system described in the above paragraph. Animated infrared imagery
indicated that deep convection was becoming organized over a weak LLCC.
An upper-level analysis indicated low vertical shear and good diffluence
aloft. The maximum winds were estimated at 20-25 kts and the development
potential was assessed as fair. At 1800 UTC on the 27th the disturbance
was located farther to the west, or about 620 nm west-southwest of
Colombo. JTWC issued a TCFA for the system at 0300 UTC on 28 November
due to increasing deep convection over the LLCC. Maximum winds were now
estimated at 25-30 kts. The first JTWC warning on Tropical Cyclone 05A
was issued at 0600 UTC on 28 November, placing the center approximately
785 nm west-southwest of Colombo, or over 1100 nm south-southwest of
Mumbai, tracking west at 10 kts. The initial warning intensity of 35 kts
was based on CI estimates of 35 and 45 kts.
The initial warning location of TC-05A's center was only 42 nm north
of the equator! The lowest latitude system so far to date was Typhoon
Vamei in December, 2001, which was a typhoon only 90 nm north of the
"line". However, even more astounding is a QuikScat image taken of the
pre-warning circulation at 27/0107 UTC. This image clearly shows a
broad, somewhat elongated circulation with a COUNTERCLOCKWISE spin
centered about a half-degree SOUTH of the equator! It appears that this
system of Northern Hemisphere origin dipped just south of the equator
and then came back without losing its counterclockwise rotation. It
would be a pretty good bet to say that this is the first documented case
of such an occurrence.
B. Synoptic History
-------------------
Having apparently survived its excursion just south of the equator,
the tropical cyclone embarked on a generally northwestward track across
the Arabian Sea which it would follow for most of its life. At some
point IMD named the system Cyclonic Storm Agni, but I am not certain of
the exact time the storm became the second officially named North Indian
Ocean tropical cyclone on record. Once having reached tropical storm
intensity, Agni continued to intensify rather steadily. By 1200 UTC on
29 November JTWC had upped the MSW to 65 kts, based on CI estimates of
55 and 65 kts. The size of the CDO had decreased slightly, but outflow
remained well-defined in all directions. At this time Agni was located
about 1050 nm south-southwest of Mumbai, or approximately 920 nm east-
southeast of Cape Guardafui, Somalia. Based upon JTWC's warnings,
Agni maintained hurricane intensity for 18 hours before beginning to
slowly weaken.
Continued weakening was forecast as Agni was moving into a region of
moderate vertical shear and drier air. The MSW was lowered to 40 kts
at 0000 UTC on 2 December when the storm was centered approximately
375 nm southeast of Cape Guardafui. Satellite CI estimates at the time
ranged from 35 to 45 kts. Agni was by now moving on more of a westerly
course as it tracked along the southern periphery of the subtropical
ridge. Deep convection continued to cycle over the storm as it continued
plodding toward the Somalian coastline. This apparently led to some
satellite analysts assigning Dvorak ratings as high as T3.5, but JTWC
maintained the MSW at 40 kts during this period. However, by 03/1800
UTC CI estimates had dropped to 25 and 35 kts, and with the system
having encountered a hostile environment of dry, continental air and
reduced outflow, JTWC issued the final warning on Agni, locating the
weakening 30-kt center about 240 nm south-southeast of Cape Guardafui.
C. Further Discussion
---------------------
Regarding the maximum intensity of Severe Cyclonic Storm Agni, Karl
Hoarau feels that early on 30 November the intensity could have been as
high as 80-85 kts. According to Dr. Hoarau, the Dvorak embedded center
technique with the EIR imagery would have yielded Data-T numbers of
4.5 or 5.0. Also, microwave images showed a much better signature with
an eye at 30/0239 UTC, which was not the case on the 29th. I do not
know the maximum intensity assigned Agni by IMD, but I do have a copy
of an IMD warning for 30/1200 UTC which estimates the MSW at 55 kts and
forecast to increase to 65 kts in six hours. This is the basis for my
referring to the system as Severe Cyclonic Storm Agni in the title line
above.
D. Damage and Casualties
------------------------
There are no known damage or casualties resulting from Severe Cyclonic
Storm Agni.
(Report written by Gary Padgett)
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for November: 1 severe tropical storm **
1 very intense tropical cyclone
** - this system classified as a minimal hurricane (cyclone) by JTWC
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 November
-----------------------------------------------------
The first two named tropical cyclones of the Southern Hemisphere
season formed in the Southwest Indian Ocean basin during November. Both
formed well to the east of Diego Garcia and equatorward of latitude 10S.
Arola became a severe tropical storm with peak winds reaching 60 kts,
but Bento became the most intense Southwest Indian cyclone to form north
of 10S--the cyclone reached its peak intensity of 120 kts at latitude
8.5S. Both systems passed south of Diego Garcia but at a sufficient
distance that there were no significant effects felt on the island.
Reports on both Arola and Bento follow.
SEVERE TROPICAL STORM AROLA
(MFR-03 / TC-03S)
7 - 13 November
-----------------------------------------------
Arola: contributed by Lesotho
A. Storm Origins
----------------
Early on 7 November (UTC) an area of convection lay approximately
630 nm east-northeast of Diego Garcia. Animated infrared satellite
imagery revealed a mid-level circulation becoming more organized over a
possible weak LLCC. An upper-level analysis indicated moderate
diffluence in the poleward direction with weak to moderate vertical shear
under the subtropical ridge axis. MFR initiated bulletins on Tropical
Disturbance 03 at 07/0600 UTC with a very weak 15-kt center located
about 650 nm east of Diego Garcia. Deep convection continued to
persist near the LLCC and the winds were increased to 25 kts at 1800
UTC. JTWC issued a TCFA for the system at 0200 UTC on 8 November as
the system continued to display increased organization.
B. Synoptic History
-------------------
The system continued to increase in organization and at 0600 UTC on
8 November MFR upgraded the disturbance to tropical depression status,
i.e., 30-kt winds. (At the same time JTWC issued the first warning on
TC-03S with the 1-min avg MSW estimated at 35 kts.) Six hours later
MFR upgraded the depression to tropical storm status with Mauritius
assigning the name Arola. Tropical Storm Arola was then located about
400 nm east-southeast of Diego Garcia with the MSW estimated at 45 kts
(10-min avg). Arola was moving west-southwestward and this motion was
forecast to continue as the system remained under the steering influence
of an anticyclone anchored to the south of the storm. Arola continued
to intensify rapidly on the 8th of November--by 1800 UTC the storm had
reached its peak intensity of 60 kts, increasing from 30 kts in only
12 hours. The minimum CP estimated by MFR was 976 hPa. At this point
Arola exhibited a very strong poleward outflow channel. Surface inflow
also was strong with feeder bands stretching over 300 nm equatorward
from the center.
Severe Tropical Storm Arola maintained its 60-kt intensity for
24 hours, then began to slowly weaken. By 09/1800 UTC convection had
decreased and the center had become partially-exposed. "Slowly"
describes Arola in two ways on the 10th through 12th of November--it
very slowly weakened and also moved very slowly, generally in a west-
southwesterly direction. The MSW had dropped to 45 kts by 1200 UTC
on the 10th, and to minimal tropical storm intensity of 35 kts 24 hours
later. At 12/0600 UTC Arola was downgraded to a 30-kt tropical
depression while located approximately 285 nm south-southeast of Diego
Garcia. The weakening depression continued to drift westward for the
next day or so--the final bulletin on the system at 13/1200 UTC placed
the center about 400 nm southwest of Diego Garcia.
The peak intensity estimated by JTWC was 75 kts (1-min avg) at 0000
UTC on 9 November, up from 45 kts six hours earlier. This was based on
CI estimates of 65 and 77 kts. However, six hours later the MSW was
dropped to 65 kts. Satellite imagery revealed that the convection had
greatly weakened and that the eye had disappeared. This sharp increase
in the reported winds and subsequent quick reduction suggests that
perhaps the 75-kt estimate at 09/0000 UTC was a little high.
C. Damage and Casualties
------------------------
No damage or casualties are known to have resulted from Severe
Tropical Storm Arola.
(Report written by Gary Padgett)
VERY INTENSE TROPICAL CYCLONE BENTO
(MFR-04 / TC-04S)
20 - 30 November
-------------------------------------------------------
Bento: contributed by Mozambique
A. Storm Origins
----------------
An area of convection developed and persisted on 18 November roughly
365 nm east of Diego Garcia. Animated multi-spectral imagery and data
from an 18/1240 UTC QuikScat pass revealed that convection was beginning
to consolidate around a well-defined and elongated LLCC. An upper-level
analysis indicated low to moderate vertical shear and favorable
divergence aloft, and an increase in 850-mb vorticity had also been
noted. The disturbance drifted westward and 24 hours later was located
approximately 310 nm east of Diego Garcia. MFR began issuing bulletins
on the developing disturbance at 0600 UTC on 20 November, designating it
as Tropical Disturbance 04 and locating the center about 300 nm east of
Diego Garcia with winds estimated at 25 kts, locally 30 kts in the
southern quadrants. Convection gradually increased in organization near
the LLCC and the upper-level environment remained favorable for
strengthening. The system was upgraded to a 30-kt tropical depression
at 21/0000 UTC when located approximately 325 nm slightly south of due
east of Diego Garcia.
B. Synoptic History
-------------------
JTWC initiated warnings on TC-04S at 21/0600 UTC, and six hours later
the system became Tropical Storm Bento, located about 375 nm east-
southeast of Diego Garcia with 40-kt winds (10-min avg). Bento steadily
increased in intensity, reaching cyclone (i.e., hurricane) status by
1200 UTC on 22 November when located about 300 nm east-southeast of Diego
Garcia. Interestingly, at 1800 UTC on the 21st satellite CI estimates
were ranging from 45 to 77 kts. Bento was similar to its predecessor
Tropical Storm Arola in two regards: (1) it moved rather slowly, most
of the time around 5 kts or less, and (2) it intensified rather quickly
to its peak intensity and then weakened slowly for several days.
However, the similarity ends there as Bento was much more intense than
Arola. Once having reached cyclone intensity at 22/1200 UTC, Bento
deepened very rapidly, reaching its peak intensity of 120 kts within
24 hours. The very intense cyclone was at this time located about
175 nm east-southeast of Diego Garcia, at latitude 8.5S. According
to Karl Hoarau, Bento is the first South Indian cyclone on record to
reach this extreme intensity equatorward of 10S. JTWC's estimated peak
1-min avg MSW of 140 kts compares very well with MFR's intensity. All
satellite agencies assigned a Dvorak rating of T7.0 to Bento on the 23rd.
Bento was a somewhat compact tropical cyclone with gales covering an area
only around 200 nm in diameter. The minimum CP estimated by MFR was
905 hPa.
Tropical Cyclone Bento maintained its peak intensity of 120 kts for
an 18-hour period, and then began to slowly weaken on the 24th. The
initial weakening was likely due to an eyewall replacement cycle which
was evident in satellite imagery. During its most intense phase Bento
tracked slowly in a west-southwesterly direction under the steering
influence of a subtropical ridge anchored to the south of the cyclone.
Convection was beginning to decrease by 24/1800 UTC due to some dry
air intrusion, and at 25/0000 UTC MFR lowered the MSW to 95 kts. By
this time Bento had made a fairly abrupt turn to the south-southeast
around the western periphery of the mid-level steering ridge toward
a weakness created by a passing mid-latitude trough. In addition to
the dry air the cyclone was moving into a region of increasing vertical
shear. By 1800 UTC on 25 November the MSW had dropped to 70 kts, and
six hours later MFR downgraded Bento to a tropical storm, located about
350 nm south-southeast of Diego Garcia.
The weakening Bento continued to track slowly in a general south-
southeasterly direction for the next few days. The storm's intensity,
based on MFR's analysis, remained pegged around 50-55 kts for a three-
day period from the 26th through 28th, and JTWC's 1-min avg MSW estimates
were in general agreement. However, there is some evidence that Bento
may have been stronger than this on the 27th and 28th. Two consecutive
QuikScat passes over the cyclone--one at 27/1211 UTC and the other at
28/0040 UTC--show winds of up to 75 kts or stronger. According to Roger
Edson it is highly unlikely that these winds are artificially too high.
The satellite agencies were all reporting Dvorak ratings of T3.0 and
T3.5 around this time. In Roger's opinion the CI was not behaving the
way it is "supposed" to, and he considered this very possible since
Bento had a large wind field and could possibly take longer than normal
to wind down. By late on the 27th the LLCC had become decoupled from the
deep convection and by 28/0600 UTC the center had become fully-exposed.
Convection continued to decrease, and JTWC issued their final warning
on Bento at 0600 UTC on 29 November. The LLCC was drifting westward
while the sheared convection was tracking southeastward. MFR downgraded
Bento to a tropical depression at 29/1200 UTC--the system was then
located approximately 575 nm south-southeast of Diego Garcia. The
system continued to weaken and the final bulletin was issued at 1200 UTC
on the 30th, placing the center about 615 nm south of Diego Garcia. The
MSW had decreased to 25 kts but winds up to 30 kts were still considered
possible in isolated locations in the southern semicircle.
C. Damage and Casualties
------------------------
Tropical Cyclone Bento remained well-removed from any populated
regions during its lifetime and there have been no reports of damage
or casualties resulting from the storm.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for November: No tropical cyclones
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NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for November: No tropical cyclones
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SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for November: No tropical cyclones
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SPECIAL FEATURE - SOURCES OF TROPICAL CYCLONE INFORMATION
The purpose of this section is to list some websites where many and
varied types of tropical cyclone information are archived. Many readers
will know about these already, but for the benefit of those who don't,
I wanted to include them.
(1) Aircraft Reconnaissance Information
---------------------------------------
Various types of messages from reconnaissance aircraft may be
retrieved from the following FTP site:
<ftp://ftp.nhc.noaa.gov/pub/products/nhc/recon/>
Information regarding how to interpret the coded reconnaissance
messages may be found at the following URL:
<http://www.nhc.noaa.gov/reconlist.shtml>
Links are also included to websites with further information about the
U. S. Air Force 53rd Weather Reconnaissance Squadron and the NOAA Air-
craft Operations Center.
(2) Archived Advisories
-----------------------
All the advisory products (public advisories, forecast/advisories,
strike probabilities, discussions, various graphics) issued by TPC/NHC
are archived on TPC's website. For the current year (using 2004 as an
example), the archived products can be found at:
<http://www.nhc.noaa.gov/archive/2004/index.shtml>
Links to tropical products archives for earlier years are available at
the following URL:
<http://www.nhc.noaa.gov/pastall.shtml>
JTWC warnings for past storms are archived on the NRL Monterry website:
<http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen.
I am not aware at the moment of any other TCWC which archives all
its tropical cyclone warning/advisory products for public access, but
if I learn of any, I will add them to this list.
(3) Satellite Imagery
---------------------
Satellite images of tropical cyclones in various sensor bands are
available on the NRL Monterrey and University of Wisconsin websites,
courtesy of Jeff Hawkins and Chris Velden and their associates. The
links are:
<http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
<http://cimss.ssec.wisc.edu/tropic/tropic.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen. For the CIMSS site, a link to data archives is
located in the lower left portion of the screen.
I'm sure there are other sites with available imagery available, and
as I learn of them, I will add the links to this list.
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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 August, 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.
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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
from the archive sites listed below. (Note: I do have a limited e-mail
distribution list for the track files. If anyone wishes to receive
these via e-mail, please send me a message.)
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. Back issues can be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Michael Pitt, Chris
Landsea, and John Diebolt):
<http://australiasevereweather.com/cyclones/>
<http://www.typhoon2000.ph>
<http://mpittweather.com>
<ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
<http://www.tropicalcyclone2005.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.metoffice.gov.uk/weather/tropicalcyclone>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the Annual Tropical Cyclone
Report (ATCR) for 2004 (2003-2004 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 2004 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2004 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 McLeans Ridges, New South Wales,
Australia, for assisting me with proofreading the summaries.
PREPARED BY
Gary Padgett
E-mail: garyp@alaweb.com
Phone: 334-222-5327
Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South
China Sea)
E-mail: newchapelobservatory@btinternet.com
John Wallace (Assistance with Eastern North Pacific)
E-mail: dosidicus@aol.com
Huang Chunliang (Assistance with Western Northwest Pacific, South
China Sea)
E-mail: huangchunliang@hotmail.com
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: saclarke@iprimus.com.au
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