MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
SEPTEMBER, 2003
Part 2
(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 September summary is being disseminated in two
installments. The first part covered tropical cyclones forming during
the first half of the month, plus contained the Feature of the Month.
This second installment covers storms forming during the latter half
of the month.
*************************************************************************
SEPTEMBER HIGHLIGHTS
--> Long-lived intense Cape Verde hurricane makes devastating strike on
U. S. East Coast--still a tropical storm in Ontario, Canada
--> Nova Scotia experiences significant hurricane damage
--> Another hurricane strikes the Baja California Peninsula and moves up
entire Gulf of California
--> Very deadly and devastating typhoon strikes South Korea
--> Unusually early-season tropical storm forms in Southwest Indian Ocean
*************************************************************************
***** Feature of the Month for September *****
NOTE!!! The Feature of the Month was included in Part 1 of the
September summary.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for September: 1 tropical depression
1 tropical storm
1 hurricane
2 major hurricanes **
** - one of these did not reach major hurricane status until October
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:
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.
Atlantic Tropical Activity for September
----------------------------------------
September was an active month in the Atlantic basin. Over the period
1950-2002, the month of September has averaged 3.5 named tropical storms,
2.4 hurricanes, and 1.25 intense (Category 3+) hurricanes. September of
2003 produced 4 named storms, 3 hurricanes, and 1 intense hurricane.
(Kate, which formed in September, did not reach major hurricane status
until October.) Over the 1950-2002 period, September has averaged about
three intense hurricane days. This year, there were 13.5--due to the
long-lived Cape Verde hurricanes Fabian and Isabel.
As the month opened, Fabian was already a major hurricane and
continued to intensify, reaching its peak intensity on 1 September.
On the 5th the large, severe hurricane passed directly over the island
of Bermuda as a Category 3 hurricane on the Saffir/Simpson scale--the
most intense storm to strike the island since 1926. Since Fabian
originated in August, it was covered completely in the August tropical
cyclone summary. Also, on the first couple of days in September, the
remnants of former Tropical Storm Grace were weakening over Texas and
Arkansas.
Tropical Storm Isabel was christened in the eastern Atlantic on
6 September, and subsequently became the first Category 5 hurricane in
the Atlantic basin since Hurricane Mitch in October, 1998. Isabel
reached a peak intensity of 145 kts and maintained intense hurricane
status for 8 days, Category 4 intensity for 6.75 days, and was a
Category 5 hurricane for a total of 2.25 days. Isabel fortunately
weakened as it approached the U. S. East Coast, and was a Category
2 hurricane with 90-kt winds as it made landfall on the Outer Banks of
North Carolina.
Hurricane Juan formed on the 25th east-southeast of Bermuda.
Initially more subtropical in nature, Juan soon acquired tropical storm
characteristics and reached hurricane intensity the next day. Juan
pursued a basic northward trajectory which carried the hurricane inland
near Halifax, Nova Scotia, on the 29th as a Category 2 hurricane. The
storm was reported to be the most destructive hurricane to strike the
city of Halifax in well over a century. Tropical Storm Kate formed
during the final week of September in the eastern Atlantic, briefly
reached hurricane intensity late on the 29th, and then weakened back
to tropical storm status. Kate regained hurricane intensity late on
1 October, and on the 3rd became the season's third major hurricane.
The only other tropical cyclone to form during September was Tropical
Depression 14. This system formed southeast of the Cape Verde Islands
and later moved northwestward, passing near or over the westernmost
Cape Verdes as it weakened. The official TPC/NHC storm report on TD-14,
written by James Franklin, can be found at the following URL:
<http://www.nhc.noaa.gov/2003fourteen.shtml?>
Since the TPC/NHC storm reports are now available online, I have not
written detailed preliminary reports as I usually do. Links to the
various cyclone reports can be found in the brief report on each storm.
Juan and Kate are covered in this installment--brief reports on Henri
and Isabel were included in Part 1.
UPDATE: The official TPC/NHC storm report on Hurricane Isabel, authored
by Jack Beven, is now available online at the following link:
<http://www.nhc.noaa.gov/2003isabel.shtml?>
HURRICANE JUAN
(TC-15)
25 - 30 September
-------------------------------------
Hurricane Juan formed out of the complex interaction between a
tropical wave, an upper-level LOW, and a frontal zone. The first
advisory on Tropical Depression 15 was issued at 1500 UTC on
25 September, and the system was upgraded to Tropical Storm Juan six
hours later. However, a careful analysis of all the available data
suggests that a depression had formed on 24 September. Juan moved on
a generally north-northwest to northerly track from its genesis south-
east of Bermuda and made landfall near Halifax, Nova Scotia, as a
Category 2 hurricane on the Saffir/Simpson scale.
The last time Halifax was struck by the eyewall of a hurricane was
on 21 August 1893. Juan was the most damaging hurricane to strike Nova
Scotia in modern times. According to a report on the website of the
Canadian Hurricane Centre, Juan claimed eight lives, either directly or
indirectly. (The NHC report indicates two direct fatalities with three
indirect.) Thousands of trees were blown down, and there were many
downed power lines as well as considerable structural damage. Juan also
crossed Prince Edward Island as a tropical storm. The Canadian news
media reported that the total estimated damage from Juan was around
$200 million (Canadian dollars).
The official TPC/NHC storm report on Juan, authored by Lixion Avila,
is available at the following URL:
<http://www.nhc.noaa.gov/2003juan.shtml?>
The Canadian Hurricane Centre has a page dedicated to coverage of
Hurricane Juan at the following link:
<http://www.atl.ec.gc.ca/weather/hurricane/juan/>
Also, Chris Fogarty has put together a page of many Juan-related
articles as well as pictures of storm damage:
<http://www.novaweather.net/Hurricane_Juan.html>
HURRICANE KATE
(TC-16)
25 September - 9 October
--------------------------------------------
Tropical Depression 16 formed on 25 September roughly 800 nm west-
southwest of the Cape Verde Islands. Moving northwestward for the next
couple of days, the system was upgraded to Tropical Storm Kate on the
27th. Kate proved to be stubborn, and despite south-southwesterly
vertical shear, strengthened during the following two days, briefly
attaining hurricane status on 29 September. A temporary weakening
trend set in as Kate, moving on a northeasterly track, turned abruptly
west-southwestward. The storm re-intensified and became a hurricane
once more on 1 October, and became the season's third intense hurricane
on the 3rd when winds reached 100 kts. Kate's west-southwesterly
heading veered gradually more westward and the storm reached its peak
estimated intensity of 110 kts on 4 October when located approximately
565 nm east-southeast of Bermuda.
Kate began to slowly weaken after reaching its maximum intensity.
Furthermore, it had turned northward by 6 October, then began to
accelerate north-northeastward as the MSW fell below hurricane strength.
The system became extratropical on 8 October but remained a powerful
storm as it crossed the North Atlantic, passing south of Iceland on the
9th and north of the UK the next day. The tail end of Hurricane Kate
brought gales to much of northern Scotland with gusts reaching 60 kts.
The official TPC/NHC storm report on Hurricane Kate, written jointly
by Richard Pasch and Robert Molleda, is now available online at the
following URL:
<http://www.nhc.noaa.gov/2003kate.shtml?>
(This brief report written by Kevin Boyle)
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for September: 1 tropical storm
2 hurricanes
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.
Northeast Pacific Tropical Activity for September
-------------------------------------------------
September was a month of near-normal activity in the Northeast Pacific
basin. Over the 1971-2002 period, the averages for the month are 3.5
named storms, 2.2 hurricanes, and 1.1 intense hurricanes. September of
2003 produced 3 named storms, 2 hurricanes, but no intense hurricane.
Hurricane Marty, however, became a Category 2 hurricane shortly before
striking the southern tip of Mexico's Baja California Peninsula. As the
month opened, Hurricane Jimena was beginning to weaken as it passed to
the south of Hawaii's Big Island. The storm continued to weaken as it
moved west-southwestward across the Central North Pacific, crossing the
International Dateline into the Western North Pacific just before
dissipating. Other than Marty, the other named storms forming in
September were Tropical Storm Kevin and Hurricane Linda. Kevin was just
a minimal tropical storm for only six hours while Linda reached minimal
hurricane strength for 12 hours before quickly weakening.
There was one additional system which warrants mentioning. A tropical
disturbance developed around 1000 nm west-southwest of the tip of Baja
California on 4 September. The area of low pressure remained stationary
for about 24 hours, then began a slow northward drift. On the 5th
convection increased somewhat around the center, prompting SAB to assign
a Dvorak rating of T2.5/2.5. Concurrent Tropical Weather Outlooks from
TPC/NHC indicated that a tropical depression could be forming. However,
early on 6 September convection began to diminish and the T-numbers from
SAB began to quickly come down. (This system was being rated during the
period 4-7 September, and the NRL temporary number was 91E.)
Reports for the cyclones are already available (or shortly will be)
on TPC/NHC's website, so I have not written the usual detailed
preliminary reports for these storms, but only a brief synopsis of
each which will include the link to the individual storm reports.
Hurricane Marty is covered in this installment--brief reports on Kevin
and Linda were included in Part 1.
UPDATE: The official TPC/NHC storm report on Hurricane Linda, authored
by Jack Beven, is now available online at the following link:
<http://www.nhc.noaa.gov/2003linda.shtml?>
HURRICANE MARTY
(TC-13E)
19 - 25 September
-------------------------------------
Hurricane Marty became the second hurricane in less than a month to
affect the Baja California Peninsula. Whereas Ignacio in late August
had moved to the east of Cabo San Lucas, eventually making landfall
north of La Paz and dissipating over the southern portion of the
peninsula, Marty moved directly over the Cabo as a Category 2 hurricane
and moved up the entire eastern shore of Baja California, reaching the
upper reaches of the Gulf of California as a tropical storm. The system
then weakened to a depression and meandered about the northern Gulf for
a couple of days before dissipating.
The Mexican government reported that Marty was responsible for twelve
deaths in the country. Five lives were lost when a fishing vessel sank
while the remainder of the fatalities were due to flash flooding along
rivers over the southern peninsula. Some articles about the effects
of Marty can be found at the following URL:
<http://www.reliefweb.int/w/rwb.nsf/vLND>
The official NHC storm report on Hurricane Marty, written by James
Franklin, is available online at the following link:
<http://www.nhc.noaa.gov/2003marty.shtml?>
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for September: 3 tropical depressions **
2 typhoons
1 super typhoon
** - None of these were classified as tropical depressions by JTWC. One
of these was named by PAGASA and treated as a tropical depression
by some of the other Asian TCWCs; two others were classified as
tropical depressions by JMA only.
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 September
-------------------------------------------------
As the month of September opened, intense Typhoon Dujuan was passing
just south of the southern tip of Taiwan. A couple of days later a
somewhat weaker typhoon made landfall in southeastern China near Hong
Kong. The complete report on Typhoon Dujuan was included in the August
tropical cyclone summary. Three typhoons came to life during September
with Super Typhoon Maemi by far the most significant. The intense storm
peaked at 150 kts on the 10th, and although somewhat weaker by the time
it landed in South Korea, Maemi still caused much destruction and loss
of life in that nation. The other September typhoons, Choi-wan and
Koppu, both were typhoons of moderate intensity which pursued generally
northeasterly tracks that carried them southeast of Japan into the
open North Pacific.
In addition to the typhoons, three other systems were classified as
tropical depressions by one or more of the Asian TCWCs, although not by
JTWC. The first of these was tracked as a tropical depression by JMA
only on the 2nd and 3rd as it moved generally northward several hundred
miles east of the Northern Marianas. JTWC had assigned this area a
fair development potential on 31 August, but downgraded it to poor on
1 September.
Another system which only JMA referenced as a tropical depression
formed on 12 September at a fairly high latitude about 200 nm southeast
of Tokyo. JTWC initially assigned this system a fair potential for
development, but no TCFA was issued. The system consisted of a well-
defined fully-exposed LLCC with associated convection displaced to the
southeast. Shear was relatively weak, but there was very little
divergence over the area. (No track was given for this system in the
companion cyclone tracks file.)
The third tropical depression was named Quiel by PAGASA. This system,
as tracked by PAGASA, formed well to the east of the Philippines and
eventually tracked into the northern South China Sea. However, there was
a "jump" of four degrees of longitude on 17 September. This was another
confusing "monsoon mess" situation similar to that which had occurred in
August with Tropical Depression Lakay and Tropical Storm Vamco. A second
circulation arose in the general region which PAGASA dubbed Roskas and
which subsequently became Typhoon Choi-wan. More details on Quiel can
be found in the September tropical cyclone tracks file.
The reports on Typhoons Maemi, Choi-wan and Koppu were written by
Kevin Boyle and with significant contributions by Huang Chunliang. A
special thanks to these gentlemen for their assistance. Reports on
Typhoons Choi-wan and Koppu are included in this installment--a rather
detailed report on Super Typhoon Maemi was contained in Part 1. Also
included below is a rainfall report sent by Huang Chunliang concerning
rains caused by a South China Sea system, probably a monsoon depression,
in mid-September.
MONSOON DEPRESSION RAINFALL
15 - 16 September
-----------------------------------------------
The following report was prepared in its entirety by Huang
Chunliang of Fuzhou City, Fujian Province, China. A special thanks
to Chunliang for compiling and sending the information.
A. Introduction
---------------
JTWC never mentioned the system in their STWOs, neither did NRL
list it as an invest area; thus, no temporary number was assigned by
NRL. JMA was the only agency that ranked the system as a weak tropical
depression, as follows:
15/0600 UTC: TROPICAL DEPRESSION 1004 HPA AT 20N 110E
15/1200 UTC: TROPICAL DEPRESSION 1004 HPA AT 21N 110E
15/1800 UTC: TROPICAL DEPRESSION 1004 HPA AT 21N 110E
16/0000 UTC: TROPICAL DEPRESSION 1004 HPA AT 21N 109E
Judging by the satellite appearances, the system is probably best
classified as a monsoon depression, in my opinion.
Since the system was treated as a weak tropical depression by JMA,
and since it caused widespread torrential rains in the coastal area of
Guangdong Province and a few stations of the Guangxi Zhuang Autonomous
Region, a brief report is included on this system.
B. Rainfall Observations
------------------------
Provinces/Region Station Period (UTC) Rainfall
---------------- -------------- ------------------ ---------
Guangdong Doumen 14/0000 -- 15/0000 225.3 mm
Guangdong Doumen 15/0000 -- 16/0000 136 mm
Guangdong Shantou 14/0000 -- 15/0000 109.1 mm
Guangdong Shanwei 14/0000 -- 15/0000 146.5 mm
Guangdong Yangjiang 15/0000 -- 16/0000 126.0 mm
Guangdong Zhongshan 14/0000 -- 15/0000 222 mm
Guangdong Zhongshan 15/0000 -- 16/0000 172 mm
Guangdong Zhuhai 15/0000 -- 16/0000 142 mm
Guangdong Boluo 15/0000 -- 16/0000 123 mm
Guangdong Panyu 15/0000 -- 16/0000 123 mm
Guangdong Yangchun 16/0000 -- 17/0000 142.8 mm
Guangxi Lipu 16/0000 -- 17/0000 142.5 mm
Guangxi Jinxiu 16/0000 -- 17/0000 146.2 mm
Note: In Guangdong Province, storm totals (14/0000 -- 17/0000 UTC)
exceeded 250 mm in the cities/counties/districts of Zhongshan, Doumen,
Shunde, Panyu, Zhuhai, Yangchun and Jieyang, with Zhongshan reporting
the highest amount of 420.3 mm.
(Report written by Huang Chunliang)
TYPHOON CHOI-WAN
(TC-16W / 0315 / ROSKAS)
17-24 September
--------------------------------------------
Choi-wan: contributed by Hong Kong, China, means 'colourful cloud';
also the name of a housing estate in Hong Kong
Roskas: PAGASA name, is the name for the screw--a piece of hardware
A. Storm Origins:
-----------------
Typhoon Choi-wan did not take too long to develop out of an area of
deep convection initially located approximately 480 nm south-southeast
of Okinawa at 0130 UTC on 17 September. Indeed, only 16.5 hours elapsed
from JTWC's initial reference in the STWO issued at 17/0130 UTC to the
first warning at 1800 UTC later that same day. Animated multi-spectral
imagery and a 16/2215 UTC microwave pass indicated that the area of deep
convection was located on the northeast edge of a broad trough. Even
though the convection appeared rather disorganised, it was under an area
of weak vertical wind shear and favourable diffluence aloft, so the
potential for development at this stage was assessed as fair. This was
upgraded to good and a TCFA released when the LLCC was seen to
consolidate and organise in both animated enhanced infrared pictures and
microwave imagery. The first warning followed at 17/1800 UTC on
Tropical Depression 16W, located approximately 250 nm south-southeast of
Okinawa, Japan. Initial movement was toward the northwest at 8 kts.
B. Storm History
----------------
PAGASA had already assigned their internal name Roskas by the time
of the first JTWC warning, and following JMA's upgrade to a tropical
storm (40 kt, 10-min avg) at 0000 UTC on 18 September, the depression
was christened Choi-wan from the international naming list. Six hours
later TD-16W (Choi-wan) was relocated westward to a position approxi-
mately 285 nm south of Naha, Okinawa, based on the latest multi-spectral
imagery and a 18/0130 UTC SSM/I pass, both which suggested two possible
LLCCs associated with the system. The Prognostic Reasoning Message for
the system issued at 18/1200 UTC indicated a poleward heading as the
developing system moved into southwesterly flow associated with an east-
ward moving shortwave trough, located at the time over the Korean
Peninsula. TD-16W continued to consolidate and intensify. An 18/1121
UTC SSM/I pass in combination with satellite animations indicated the
formation of a deep convective band in the eastern semicircle. Based on
satellite CI estimates of 35 kts and 45 kts, JTWC finally upgraded
Choi-wan to tropical storm intensity with a MSW of 45 kts at 18/1800
UTC. For the past several hours Choi-wan had been moving northward at
8 kts.
By 19/0000 UTC Choi-wan was closing in on Okinawa. The northerly
heading had brought the system to a position approximately 75 nm south
of Naha. The MSW had increased to 55 kts and Choi-wan strengthened to
typhoon intensity while crossing Okinawa around 19/1200 UTC. The storm
veered north-northeastward, crossing the ridge axis, but strengthening
was forecast for the next 24 to 36 hours before Choi-wan would enter the
unfavourable westerly wind flow.
The intensity of Choi-wan remained constant with the MSW only slowly
rising to 70 kts by 20/0600 UTC and to 75 kts twelve hours later.
Outflow enhancement was noted in 20/1200 UTC microwave imagery, although
a recent QuikScat pass indicated that the low-level circulation was
slightly elongated while the microwave image revealed dry air entrainment
from the west. Typhoon Choi-wan had undergone a temporary track change--
an eastward trek--as it rode over the mid-level ridge located to the
southeast.
At 0000 UTC on the 21st Typhoon Choi-wan was moving east-northeastward
at a faster speed of 22 kts from a position approximately 365 nm south-
southwest of Tokyo, Japan. Visible satellite imagery revealed a 12-nm
diameter eye at this time. The system had resumed its intensification,
reaching a peak intensity of 95 kts at 21/0600 UTC. By this time the eye
had expanded to 45 nm in diameter with enhanced outflow continuing to the
north and northeast. However, microwave imagery at 21/1200 UTC indicated
that the upper-level circulation was beginning to tilt slightly to the
east of the LLCC. Typhoon Choi-wan started to weaken as its movement
settled into a northeasterly heading.
The MSW had dropped to 85 kts by 22/0000 UTC as shearing conditions
in the mid-level westerly zone began to separate the deep convection from
the LLCC. Typhoon Choi-wan was accelerating northeastward away from
Japan, being then centred approximately 250 nm east of Tokyo. The
associated deep convection decreased significantly as the intensity of
Choi-wan fell to 80 kts at 22/0600 UTC, to 70 kts six hours later, and
to below typhoon strength at 1800 UTC, by which time extratropical
transition was complete and the last warning issued by JTWC. The last
warning position was near 39.4N, 151.1E, or 450 nm east of Misawa, Japan.
The extratropical remnants of Choi-wan, as tracked by JMA, sped east-
northeastward across the northern Pacific. By 0000 UTC on 24 September
the system had crossed the International Dateline and had weakened into
a 40-kt gale south of the Aleutians.
(Editor's Note: The peak 10-min avg MSW and minimum CP as reported
by JMA were 70 kts and 960 hPa, respectively. CWBT also estimated
the peak intensity of Choi-wan at 70 kts, whereas NMCC's peak MSW
was higher at 80 kts. Choi-wan/Roskas had exited PAGASA's AOR long
before the peak intensity was reached.)
C. Meteorological Observations
------------------------------
The following meteorological observations were compiled and sent by
Huang Chunliang. A special thanks to Chunliang for sending the
information.
1. Peak Wind Reports
--------------------
NOTE: All sustained wind speeds reported below are 10-min avg winds.
(a) Station: Naha, Okinawa (WMO 47936)
Lat 26.2N, Lon 127.7E, Alt 28 m
Winds reached a sustained speed of 36 kts at 19/1350 UTC with a peak
gust of 60 kts recorded at 19/1157 UTC.
(b) Station: Nago, Okinawa (WMO 47940)
Lat 26.6N, Lon 128.0E, Alt 6 m
Peak MSW of 36 kts occurred at 19/1240 UTC and the highest gust
recorded was 62 kts at 19/1502 UTC.
(c) Station: Ojima, Tokyo (WMO 47675)
Lat 34.8N, Lon 139.4E, Alt 74 m
Gale-force winds of 33 kts were reported at 1510 UTC on 21 September,
gusting to a top speed of 64 kts at 21/1934 UTC.
(d) Station: Hachijojima , Tokyo (WMO 47678)
Lat 33.1N, Lon 139.8E, Alt 79 m
A MSW of near typhoon force, 62 kts, was recorded at 21/1510 UTC, while
a top gust of 116 kts was reported at 1434 UTC on the 21st. A gust of
99 kts, occurring at 21/1430 UTC, was highlighted in a JMA local warning.
Winds first reached sustained gale force from the east-northeast at
21/1300 UTC, increasing to storm force by 22/1500 UTC. By 1600 UTC the
MSW began to ease while the SLP started to rise after the minimum of
958.6 hPa was reached at 1533 UTC. Winds continued at gale force for
another two hours from the north until between 1700 and 1800 UTC when
they fell below 35 kts.
(e) Station: Miyakejima, Tokyo (WMO 47677)
Lat 34.1N, Lon 139.5E, Alt 36 m
A MSW of 57 kts was recorded at 21/1300 UTC with a gust of 80 kts at
21/2108 UTC.
(f) Station: Choshi, Chiba (WMO 47648)
Lat 35.7N, Lon 140.9E, Alt 20 m
Sustained winds reached 50 kts at 21/2250 UTC while earlier at 2108 UTC
a peak gust of 68 kts occurred.
(g) Station: Ajiro, Shizuoka (WMO 47668)
Lat 35.1N, Lon 139.1E, Alt 67 m
The MSW reached 39 kts at 21/1550 UTC with a peak gust of 61 kts at
21/1632 UTC.
The following gust reports below were taken from JMA local warnings
and cannot be taken as peak values.
(h) Station: Okinoerabu, Kagoshi (WMO 47942)
Lat 27.4N, Lon 128.7E, Alt 27 m
19/0851 UTC 69 kts
19/1046 UTC 81 kts
19/1155 UTC 82 kts
(i) Station: Yakushima, Kagoshima (WMO 47836)
Lat 30.4N, Lon 130.7E, Alt 36 m
20/0640 UTC 52 kts
(2) Minimum Sea Level Pressure Observations
-------------------------------------------
Naha, Okinawa 985.8 hPa (19/0608 UTC)
Nago, Okinawa 983.8 hPa (19/1004 UTC)
Hachijojima, Tokyo 958.6 hPa (21/1533 UTC)
Note: Only stations that reported sea level pressures below 990 hPa are
included above.
3. Storm Total Rainfall Observations
------------------------------------
The most torrential hourly amount associated with Choi-wan was
recorded in Hachijojima during the 1-hr period ending at 21/1512 UTC,
accumulating to 91.5 mm. The maximum storm total for the period 19/1500
UTC-22/0300 UTC was 281.0 mm.
Other stations (in Japan) which received storm totals above 200 mm
during the period 19/1500 UTC-22/0300 UTC were:
Miyakejima, Tokyo WMO 47677 288.5 mm
Miyake-Ako, Tokyo JMA 44227 316 mm
Miyake-Izu, Tokyo JMA 44229 291 mm
Ojima, Tokyo WMO 47675 211.0 mm
Amagisan, Shizuoka JMA 50427 228 mm
A couple of rainfall amounts from Okinawa for the period 17/1500
UTC-19/1500 UTC include:
Naha, Okinawa WMO 47936 139.5 mm
Nago, Okinawa WMO 47940 105.0 mm
(4) Sources of Data
-------------------
1. Reports prepared by the local meteorological services of Okinawa and
Tokyo, which are under the control of JMA.
2. Raw data on the official web pages of JMA (Japanese version):
D. Damage and Casualties
------------------------
No reports of damage or casualties have been reported in association
with Typhoon Choi-wan.
(Report written by Kevin Boyle and Huang Chunliang)
TYPHOON KOPPU
(TC-17W / 0316 / SIKAT)
24 September - 2 October
--------------------------------------------
Koppu: contributed by Japan, means 'cup', and specifically refers to
the constellation Crater
Sikat: PAGASA name, means 'popular'
A. Storm Origins
----------------
A new area of convection developed near 10.0N, 141.0E, or approxi-
mately 220 nm east-northeast of Yap Island. This suspect area was
mentioned in JTWC's STWO at 0600 UTC on 22 September. The development
potential of this broad circulation was assessed as poor. This was
upgraded to fair at 23/2130 UTC as organisation improved. A surface
analysis indicated multiple circulations in the monsoon trough, while
at upper-levels a TUTT cell centred to the northeast was enhancing
outflow. At 24/0230 UTC JTWC issued a TCFA relocating the disturbance
to near 14.9N, 139.4E, or approximately 360 nm west of Saipan.
The first warning on Tropical Depression 17W was issued at 1200 UTC
on 24 September, placing the centre roughly 480 nm west-northwest of
Guam. The exact location of the LLCC was still highly uncertain at
this point as the system remained embedded within the broad trough.
Movement was toward the west-northwest at 10 kts and this heading
continued into the 25th. Intensification was slow and the MSW remained
at 25 to 30 kts through the 25th and 26th due to the hindering effects
of the TUTT cell located to the northeast. During this time the
depression began a slow northward drift, and then finally reached
tropical storm intensity at 27/0000 UTC. A northeastward acceleration
had started in response to a shortwave trough heading toward Japan as
well as to changes in the position of the equatorial and subtropical
ridges.
(Editor's Note: PAGASA issued only four warnings on this system as
Tropical Depression Sikat, well before it had reached tropical storm
intensity. The final PAGASA warning was issued at 0000 UTC on
26 September as Sikat was moving northeastward out of the agency's
AOR.)
B. Track and Intensity History
------------------------------
JMA named this system Koppu just prior to JTWC's upgrade to a 50-kt
tropical storm at 27/0000 UTC. At this time it was located approximately
234 nm south-southwest of Iwo Jima, moving north-northeastward at 16 kts.
After some additional strengthening the intensity of Koppu remained
static at 60 kts for a day or so. Then, following the appearance of a
60-nm ragged eye on the 28/1154 UTC SSM/I pass (infrared satellite
imagery had revealed an eye feature earlier in the day), Koppu was
upgraded to a 70-kt typhoon at 28/1200 UTC, by which time it had slowed
to a 2-kt crawl as it moved through the ridge axis. Earlier, Koppu had
made its closest approach to Iwo Jima at 28/0000 UTC, passing 50 nm to
the west of the island.
Typhoon Koppu began to accelerate once again at 0000 UTC on
29 September. At this time it was centred approximately 160 nm north of
Iwo Jima, moving north-northeastward at 9 kts with the MSW estimated
at 80 kts. A peak intensity of 90 kts was reached at 29/0600 UTC, and
soon afterward, a weakening trend began. The eye faded, deep convection
weakened and the circulation took on an elongated appearance. Koppu was
now undergoing extratropical transition as it continued to accelerate
northeastward at 20 kts.
At 0000 UTC on 30 September, Koppu, barely a typhoon, lay
approximately 390 nm east-southeast of Tokyo, Japan. Convection had
almost completely sheared away and extratropical transformation was
nearly complete. Koppu was downgraded to a tropical storm at 30/0600
UTC and the final warning issued by JTWC. The remnant extratropical
storm could be followed for several more days as it moved south and east
of the Kamchatka Peninsula. The final reference in JMA's High Seas
Bulletins, at 0000 UTC on 2 October, placed the 50-kt storm near
48.0N, 167.0E.
(Editor's Note: The peak 10-min avg MSW estimated by JMA and CWBT was
70 kts, while NMCC's peak intensity was 80 kts. The minimum CP estimated
by JMA was 960 hPa.)
C. Meteorological Observations
------------------------------
The meteorological observations in this section were compiled and
sent by Huang Chunliang. A special thanks to Chunliang for sending the
information.
(1) Hourly Sustained Wind/Pressure Observations from Chichijima
---------------------------------------------------------------
WMO 47971, Lat 27.1N, Lon 42.2E, Alt 3m)
NOTE: All MSW values are 10-min avg winds.
Winds started to increase from the southeast at 1600 UTC,
28 September, and reached gale force six hours later and storm intensity
at 0400 UTC, 29 September. During this period SLP pressure had been
falling (about 3 mb per 3 hours) and reached a minimum of 974.6 mb at
29/0300 UTC. The highest hourly sustained winds (from the south-
southwest) occurred at 29/0400 UTC, peaking at 55 kts. Winds quickly
dropped to gale force and had fallen below 30 kts by 29/0700 UTC.
A peak wind gust of 108 kts was recorded on Chichijima, Japan, at
29/0300 UTC and was the third highest gust measured at this station.
Only two storms have brought stronger gusts: Super Typhoon Marge of
1983 (116 kts) and Typhoon Ben of 1986 (114 kts). In the history of the
station, only one typhoon has brought a MSW higher than Koppu and that
was Joan of 1997 (62 kts). The highest sustained winds observed in
association with Koppu were 60 kts.
Other gust reports from Chichijima include: a gust of 69 kts at
28/2224 UTC, 78 kts at 28/2320 UTC, and 93 kts at 29/0042 UTC. All of
these observations were highlighted in the JMA local warnings and cannot
be regarded as the peak values.
(2) Sources of Data
-------------------
This report was distilled, translated and edited from the raw data
on the official web pages of JMA (Japanese version):
(3) Wind/Pressure Reports from Iwo Jima
---------------------------------------
The MSW reached a maximum of 38 kts at 28/0600 UTC and 28/1500 UTC.
A peak gust of 59 kts was recorded at 27/2100 UTC and a pressure of 982.1
hPa was also reported at this time. Also, a minimum pressure of 980 hPa
was reported at 28/0000 UTC. These reports were from 3-hourly synoptic
observations and cannot be taken as peak/minimum values.
D. Damage and Casualties
------------------------
There have been no reports of damage or casualties resulting from
Typhoon Koppu.
(Report written by Kevin Boyle and Huang Chunliang)
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for September: No tropical cyclones
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for September: 1 moderate tropical storm
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 September
------------------------------------------------------
The tropical storm season in the Southwest Indian Ocean west of 90E
got underway early with the formation of Tropical Storm Abaimba. Such
early-season storms are unusual but not all that rare in this basin.
JTWC initiated warnings on TC-01S on 29 September and upgraded the system
to minimal tropical storm status the next day. The system intensified
markedly on 1 October and was named Abaimba by the Meteorological Service
of Mauritius. Tropical Storm Abaimba meandered around at a very low
latitude several hundred miles west-northwest of Diego Garcia and had
dissipated by 4 October.
TROPICAL STORM ABAIMBA
(MFR-01 / TC-01S)
29 September - 4 October
--------------------------------------------
Abaimba: contributed by Tanzania
A. Storm Origins
----------------
The precursor to this early-season tropical storm in the Southwest
Indian Ocean was an area of convection which formed about 600 nm west
of Diego Garcia early on 29 September. JTWC issued a STWO at 0400 UTC,
noting that satellite imagery indicated cycling deep convection near
an elongated LLCC with the convection wrapping into the center. The
development potential was assessed as fair based on the presence of good
diffluence aloft and weak to moderate vertical shear. MFR issued their
first bulletin on Tropical Disturbance 01 at 0600 UTC, and JTWC followed
with a TCFA at 0930 UTC which relocated the disturbance to a position
approximately 590 nm west-northwest of Diego Garcia.
JTWC issued the first warning on Tropical Cyclone 01S at 1800 UTC,
again relocating the center--this time to a point 505 nm west-northwest
of Diego Garcia. The MSW (1-min avg) was estimated at 30 kts, based on
CI estimates of 25 and 35 kts. The system was quasi-stationary with
the LLCC located just east of the deepest convection. At 0000 UTC on
30 September MFR upped the MSW (10-min avg) to 30 kts, which qualified
the system for formal tropical depression status. JTWC upped their
MSW estimate to 35 kts (1-min avg) at 0600 UTC; at the time TC-01S was
located about 475 nm west-northwest of Diego Garcia, moving southeast-
ward at 4 kts. The LLCC was partially-exposed to the northeast of the
deep convection. The intensity remained static for the remainder of
the 30th as the depression continued moving slowly east-southeastward.
It was forecast to turn to the southwest in 12-24 hours as a low to mid-
level ridge built to the south.
B. Storm History
----------------
At 0600 UTC on 1 October the center of TC-01S was located roughly
420 nm west-northwest of Diego Garcia, moving very slowly southwestward.
Poleward outflow had improved, and the LLCC was no longer exposed. JTWC
upped the MSW to 50 kts (1-min avg), based on CI estimates of 35 and 45
kts plus QuikScat data. Also, MFR and the Mauritius Meteorological
Service upgraded the system to tropical storm status with the latter
agency assigning the name Abaimba. MFR bumped up their MSW estimate
from 30 to 45 kts (10-min avg) at 0600 UTC. However, at 1800 UTC MFR
lowered the intensity to 40 kts. JTWC's MSW remained at 50 kts, but
the warning noted that there was evidence of some cooler air infiltrating
the western side of Abaimba's circulation.
A SSM/I pass at 02/0451 UTC revealed a fully-exposed LLCC with deep
cycling convection located 100 nm to the west under 20-30 kts of north-
easterly shear. JTWC downgraded the MSW to 30 kts (1-min avg) and placed
the center about 290 nm west-northwest of Diego Garcia, moving south-
eastward at 6 kts. MFR's intensity remained at 35 kts, but this was
lowered to 30 kts at 1200 UTC. The factors responsible for Tropical
Storm Abaimba's sudden weakening were adjudged to be a lack of upper-
level outflow, increased vertical shear, and entrainment of cooler (and
likely drier) air. Interestingly, at 0600 UTC on 3 October, JTWC upped
the MSW back to 35 kts (1-min avg) and forecast Abaimba to strengthen
steadily, reaching 55 kts in 48 hours. The storm at this time was
located approximately 335 nm west-northwest of Diego Garcia, moving
slowly southwestward at 3 kts. Abaimba's organization was improving
somewhat, and the system was forecast to move into a more favorable
environment of increased outflow and reduced vertical shear.
However, Abaimba continued to present a very poorly-organized
appearance in satellite imagery. MFR dropped the MSW to 25 kts at
1200 UTC, although the bulletin noted that stronger winds were likely
occurring in isolated spots in the southwestern semicircle. At 1800 UTC
JTWC once more dropped the intensity to 30 kts, but still forecast the
system to recover and undergo some modest strengthening. At 0600 UTC
on 4 October MFR and JTWC decreased their MSW estimates to 20 kts and
25 kts, respectively. The JTWC warning indicated that CI estimates
were 25 and 30 kts, and the agency's forecast still called for Abaimba
to re-intensify to tropical storm strength. This optimistic forecast
failed to verify, however, and MFR issued their final bulletin on
the system at 1200 UTC. JTWC likewise issued their final warning on
the dissipating system at 1800 UTC, placing the center about 460 nm
west of Diego Garcia and moving west-northwestward at 6 kts. All deep
convection associated with the LLCC had dissipated during the previous
twelve hours.
C. Damage and Casualties
------------------------
No damage or casualties are known to have resulted from Tropical
Storm Abaimba.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for September: No tropical cyclones
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for September: No tropical cyclones
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for September: 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
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, and
Chris Landsea):
<http://australiasevereweather.com/cyclones/>
<http://www.typhoon2000.ph>
<http://mpittweather.com>
<ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
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 2002 (2001-2002 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 2002 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2002 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
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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