MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
SEPTEMBER, 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 September summary will be issued in three install-
ments. This first installment covers the Atlantic basin. The second
part will cover the Northwest Pacific basin and an out-of-season South
Indian Ocean cyclone. The final installment will cover the Northeast
Pacific basin and will contain the Feature of the Month.
*************************************************************************
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. After a couple of months, I will move this
note to the ending section of the summary.
(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.
*************************************************************************
SEPTEMBER HIGHLIGHTS
--> Two large, severe hurricanes pass through northern Bahamas and
strike same point on Florida's East Coast
--> Tropical storm rains cause catastrophic loss of life in Haiti
--> Long-lived intense hurricane causes great destruction on Grenada,
Jamaica, Cayman Islands, western Cuba, and north-central U. S.
Gulf Coast
--> Japan experiences yet another tropical cyclone strike
*************************************************************************
***** Feature of the Month for September *****
NOTE!!! The Feature of the Month will be contained in the third
installment of the September summary.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for September: 1 tropical depression
1 hurricane **
3 intense hurricanes
** - system actually reached hurricane intensity in early 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
----------------------------------------
The very active pattern of tropical cyclone activity observed in
August in the Atlantic basin continued into September, though at a
slightly less hectic pace. Four named tropical cyclones formed during
the month--near the long-term (1950-2003) average of 3.50. All four
of these storms reached hurricane intensity, but Tropical Storm Lisa did
not do so until 2 October, so counts as an October hurricane. The 1950-
2003 average number of hurricanes is 2.44, so September was roughly
average in that department. It was in the intense hurricane category
(MSW > 95 kts) that September was well-above the mean. The long-term
average number of intense hurricanes is 1.24, and Hurricanes Ivan, Jeanne
and Karl all achieved that distinction.
Mighty Hurricane Ivan maintained an intensity at or above Saffir/
Simpson Category 3 for 10.25 days--certainly near if not setting a new
record for longevity as an intense hurricane. The great storm reached
Category 5 status on three separate occasions during its lifetime, and
spread death and destruction from the southern Windward Islands to the
eastern United States. Hurricane Jeanne, in its early tropical storm
stages, brought torrential rains to Haiti which led to catastrophic
loss of life. After loitering around in the western Atlantic for several
days and executing a large clockwise loop, Jeanne began a westward march
which ultimately carried it across the northern Bahamas and into the
Florida Peninsula on a track almost identical to that followed by
Hurricane Frances three weeks earlier. Hurricane Karl became a very
impressive Category 4 hurricane around mid-month, but fortunately
followed a harmless track northward through the central Atlantic. On
its heels came Tropical Storm Lisa, a very tenacious storm which hung
out in the east-central tropical Atlantic for almost a week, barely
clinging to life at times, but eventually following Karl northward
on a track between Bermuda and the Azores. Lisa managed to briefly
reach minimal hurricane intensity in early October before losing its
tropical characteristics.
In addition to the named tropical cyclones, there was an additional
tropical depression for which advisories were issued. An active tropical
wave left the coast of Africa on 29 August and passed north of the Cape
Verde Islands the next day. The system became fairly well-organized on
the 31st--SAB gave it a Dvorak classification as high as T2.5/2.5 at
1800 UTC. The system likely would have been upgraded to depression
status, but the next day convection began to wane as the disturbance
moved into a less-favorable environment. Over the next several days
the system moved northwestward, then northward, and finally northeastward
over the eastern Atlantic. Deep convection had returned by the 7th,
although southwesterly shear was inhibiting development somewhat. The
system was classified as Tropical Depression 10 at 0600 UTC on the 9th
of September when located about 365 nm west-southwest of the Azores.
However, at 1800 UTC convection had diminished and all that remained was
a low-level cloud swirl; hence, advisories were discontinued. In post-
analysis, it was decided to begin the tropical depression stage at
1200 UTC on 7 September. A short report on this system, written by
Richard Pasch, is available at the following URL:
<http://www.nhc.noaa.gov/2004ten.shtml?>
Also, as the month of September opened, mighty Hurricane Frances
was passing north of the Turks and Caicos Islands at its peak intensity
of 125 kts. The large storm had fortunately weakened to Category 2
status before passing over the northwestern Bahamas and subsequently
striking the Florida coast. A full report on Frances can be found
in the August summary, and the official TPC/NHC report on Frances,
written by Jack Beven, may be found at the following URL:
<http://www.nhc.noaa.gov/2004frances.shtml?>
HURRICANE IVAN
(TC-09)
2 - 25 September
------------------------------------
A. Storm History
----------------
When I began to write this account of Hurricane Ivan, the TPC/NHC
official storm report was not available online, so I wrote a fuller
account than I would have otherwise. But I have just discovered that
the official storm report on Ivan, authored by Stacy Stewart, has now
been placed on TPC/NHC's website. However, I am still including the
report which I had written. Ivan was a classic long-lived Cape Verde
hurricane which made two landfalls along the U. S. coast and reached
Saffir/Simpson Category 5 status three times, peaking at 145 kts on
12 September when located in the northwestern Caribbean Sea near Grand
Cayman Island. The great storm's origins lay with a vigorous tropical
wave which crossed the West African coast on 31 August. The system
strengthened into the season's 9th tropical depression on the afternoon
of 2 September when located about 485 nm southwest of the Cape Verde
Islands. Tropical Storm Ivan was christened at 0900 UTC on 3 September
when the system was centered approximately 530 nm southwest of the Cape
Verdes. The system continued westward at an unusually low-latitude
(for the Atlantic) along the 9th parallel. Ivan was upgraded to
hurricane status at 0900 UTC on 5 September when located about 1050 nm
east-southeast of the Lesser Antilles. An eye had appeared and satellite
intensity estimates from TAFB and SAB supported the upgrade.
Once upgraded to a hurricane, Ivan began to intensify very rapidly.
A special advisory package was issued at 1700 UTC upgrading Ivan to
a 100-kt Category 3 hurricane, located 865 nm east of the southern
Windward Islands and moving quickly westward near 19 kts. Ivan was
upgraded to major hurricane status at latitude 10.1N--to the author's
knowledge this is the southernmost point any Atlantic hurricane on
record has achieved Category 3 status. Ivan weakened some on the 6th
and 7th--the first reconnaissance mission into the hurricane on the
afternoon of the 6th found a 90-kt hurricane. This weakening was
possibly due to some slight westerly shear induced by a weak upper-level
LOW over the east-central Caribbean, and also to an eyewall replacement
cycle. The storm began to re-intensify on the morning of the 7th and
was back to Category 3 status before it passed near the island of
Grenada that afternoon with devastating results. (Ivan was the most
destructive hurricane to strike Grenada since Hurricane Janet of 1955,
which also became an intense Category 5 hurricane in the northwestern
Caribbean.)
Many tropical cyclones have weakened or met their demise while
traversing the southeastern Caribbean Sea. Dunn and Miller in
_Atlantic Hurricanes_ attribute the lack of significant hurricane
activity in this region at least in part to the significant divergence
in the lower tropospheric easterly flow as the easterly trades are
diverted into the semi-permanent LOW over the Amazon valley. As Ivan
chugged along westward, roughly parallel to the Venezuelan coastline,
it continued to strengthen, reaching Category 5 status at 0600 UTC
on 9 September when located about 75 nm northeast of Aruba in the
Netherlands Antilles. The CP was 922 mb, down 15 mb in 7 hours, and
an eyewall dropsonde recorded 175 kts at about 192 m above MSL. Intense
Hurricane Ivan maintained its estimated 140-kt MSW for 18 hours until
being downgraded slightly to 130 kts at 10/0000 UTC. The dangerous
storm by this time had its sights set on Jamaica, about 280 nm straight
ahead as it moved west-northwestward at 11 kts. Very fortunately for
Jamaica, as Ivan approached the island during the early morning hours
of 11 September, its eye wobbled westward enough that the core of
strongest winds remained offshore. Nonetheless, the island experienced
hurricane-force winds.
During the weakening episode on 10 September, Ivan's CP rose to
937 mb at 10/1800 UTC, then began to drop again, reaching a minimum of
910 mb around 0000 UTC on the 12th. This reading ranks Ivan 6th for the
lowest Atlantic basin CP on record, behind Camille (1969) and Mitch
(1998) at 905 mb, Allen (1980) at 899 mb, the Labor Day Hurricane of
1935 at 892 mb, and Gilbert (1988) at 888 mb. The MSW was estimated at
145 kts at this time and hurricane-force winds extended outward from
the center 30 nm to the southwest and 60 nm in the other quadrants.
The storm at this time was located about 115 nm southeast of Grand
Cayman, moving generally in a west-northwesterly direction. Ivan main-
tained its peak intensity for a 12-hour period before being downgraded
to Category 4 status again at 12/1200 UTC. This slight weakening trend
was likely due to an eyewall replacement cycle. The great storm weakened
only to 130 kts before being upgraded to Category 5 status (140 kts) for
the third time at 0600 UTC on 13 September. Ivan at this time was
located about 140 nm southeast of the western tip of Cuba, still moving
slowly west-northwestward. The hurricane's third round at Category 5
status was the longest--30 hours--with the CP dipping down to 912 mb
for a secondary minimum at 13/1800 UTC. Around 0000 UTC on 14 September
the extremely dangerous hurricane's center passed just off the western
tip of Cuba. Ivan's track by this time had become more northwesterly as
the cyclone headed into the confines of the Gulf of Mexico.
As the hurricane continued north-northwestward into the Gulf of
Mexico on the morning of the 14th, it began to slowly weaken, likely
due to a combination of an eyewall replacement cycle, the entrainment of
some very dry air and a restriction of the outflow in the northwestern
quadrant. The MSW had dropped to 120 kts by 14/1800 UTC where it
remained pegged for 24 hours. After the completion of the eyewall cycle,
convection made a temporary comeback, and since Ivan was forecast to
pass over a warm eddy during the next day or so, a modest strengthening
was anticipated. However, this did not materialize and the MSW was
reduced to 115 kts at 1800 UTC on 15 September. Ivan was centered
at this time about 150 nm south of the Alabama coastline and had made
an expected turn to the north. Hurricane-force winds extended outward
90 nm to the east of the center and 75 nm to the west while gales
covered an area 400 nm in diameter. Throughout the afternoon and evening
of the 15th and into the early morning hours of the 16th, the great storm
continued inexorably toward the Alabama coastline. The center of Ivan's
eye appears to have made landfall near Gulf Shores, Alabama, shortly
after 0700 UTC on the morning of 16 September with the MSW estimated at
113 kts--an upper-end Category 3 hurricane. (The intermediate advisory
nearest landfall gave the MSW as 130 statute miles-per hour, or 113 kts.)
NOTE: In post-storm analysis it has been determined that Ivan's MSW at
landfall was 105 kts.
Hurricane Ivan continued moving inland through west-central Alabama
as it gradually weakened. At 1800 UTC the cyclone was downgraded to
tropical storm status while passing about 70 km west-northwest of
Montgomery, Alabama. The weakening Ivan continued north-northeastward
across Alabama, dropping copious amounts of rainfall, and was down-
graded to a tropical depression during the evening of the 16th while
located about 40 km north-northwest of Gadsden, Alabama. This was
accomplished on the final TPC/NHC advisory, issued at 17/0300 UTC.
Warning responsibility was then assumed by HPC in Maryland. The residual
depression continued moving northeastward across the southeastern U. S.,
finally emerging into the Atlantic off the Delmarva Peninsula as an
extratropical gale. This LOW became elongated and the southern portion
of the surface circulation moved southwestward just off the southeastern
U. S. coast, eventually passing over south Florida and into the Gulf of
Mexico on 21 September.
This system began to show signs of intensification, and advisories
were re-initiated on Tropical Depression Ivan at 2300 UTC on the 22nd,
placing the center about 135 nm south of the mouth of the Mississippi
River. Intensification continued and a reconnaissance plane during the
evening measured a peak FLW of 47 kts within a convective band to the
north of the center; hence, the depression was re-upgraded to Tropical
Storm Ivan at 0300 UTC on 23 September. The resurrected Ivan continued
moving northwestward toward the western Louisiana/eastern Texas coasts.
A peak intensity of 50 kts during this second phase of Ivan's colorful
career was attained at 23/1500 UTC when a reconnaissance plane found
70-kt winds at 450 m during the morning within a burst of deep convection
which had fired off near the LLCC earlier in the morning. However,
thunderstorm activity subsequently dwindled and Ivan began to weaken.
Tropical Storm Ivan crossed the coast just west of Cameron, Louisiana,
around 0000 UTC on the 24th with peak winds estimated near 40 kts. The
system was downgraded once more to a depression at 24/0300 UTC and the
second "final" TPC/NHC advisory was issued at 0900 UTC with Ivan
weakening over southeastern Texas. HPC issued four advisories on Ivan,
the final one at 25/0900 UTC after the remnant LOW had become no longer
discernible in surface observations.
According to a discussion bulletin from NHC, the debate over what to
call the rejuvenated tropical cyclone in the Gulf of Mexico on the 22nd
of September was at times animated. Many tropical cyclone enthusiasts
and professional meteorologists on various discussion groups were fully
expecting the system to be named Matthew--the next available name on
the list. The decision to apply the name Ivan to the cyclone came
somewhat of a surprise. The NHC discussion bulletin at 23/2300 UTC
states that the decision was based primarily on the reasonable continuity
observed in the analysis of the surface and low-level circulation.
B. Meteorological Observations
------------------------------
The aforementioned TPC/NHC official storm report on Hurricane Ivan can
be accessed at the following link:
<http://www.nhc.noaa.gov/2004ivan.shtml?>
Table 3 in the report lists selected surface observations made during
the hurricane's lifetime. The highest sustained wind recorded in
Grenada was 64 kts, gusting to 101 kts, at Point Salines. Grand Cayman
reported the highest wind recorded during Ivan's history--indeed the
highest wind recorded on land in an Atlantic hurricane in many years.
At 12/1500 UTC the station recorded a peak 1-min avg wind of 130 kts
with a peak gust of 149 kts. Cabo de San Antonio, Cuba, reported a
MSW of 96 kts with a peak gust of 104 kts as the storm passed just off
the western tip of the island. An automated weather observation station
on the oil drilling platform Ram Powell-VJ956, located about 70 nm south
of Mobile, Alabama, reported a sustained wind of 102 kts with a gust to
135 kts at 15/2256 UTC. (The instrument's elevation was 121.9 m above
MSL.) The strongest winds measured in the U. S. were an unofficial
report from a storm chaser near Gulf Shores, Alabama, of a sustained
wind of 77 kts with a gust to 99 kts at 0602 UTC on 16 September. The
Pensacola Naval Air Station reported a peak wind of 76 kts with a gust
to 93 kts at 16/0629 UTC. Television station WEAR-TV in Pensacola
recorded a storm total rainfall of 401 mm.
Interested persons should consult the Ivan report for more detailed
information.
C. Damage and Casualties
------------------------
Ivan is responsible for at least 94 deaths: 39 in Grenada, 26 in
the United States, 18 in Jamaica, 4 in the Dominican Republic, 3 in
Venezuela, 2 in the Cayman Islands, and 1 each in Tobago and Barbados.
The storm was also indirectly responsible for 31 deaths in the U. S.
The total U. S. monetary losses due to Ivan have been estimated
at $15 billion, ranking Ivan as the 3rd most destructive U. S. hurricane
to date, after Andrew (1992) and Charley (2004). The effects of wind
and water along the Alabama and western Florida Panhandle coastlines
left behind incredible devastation. As the slowly-weakening cyclone
moved northward through west-central Alabama, thousands of homes suffered
extensive damage due to trees falling on them. Homes in Montgomery,
Alabama, about 250 km inland, suffered extensive damage from falling
trees. Downed trees were also reported as far inland as Birmingham
and Atlanta. Millions of board feet of timber were blown down in the
forests and woodlands of Northwest Florida and Alabama.
Ivan left behind a trail of great destruction across the Caribbean.
Grenada and the Cayman Islands were especially hard-hit, with Cuba,
Jamaica and other islands also experiencing significant damage. The
Caribbean Development Bank has estimated the damage in the region at
more than US$3 billion. In the Caymans about 95% of the homes and
other buildings were damaged or destroyed, and on Grenada more than
14,000 homes were damaged or destroyed, and 80% of the nutmeg trees
were destroyed. On Jamaica at least 47,000 homes were damaged with
5600 being completely destroyed.
Many articles concerning Ivan's rampage through the Caribbean can be
accessed at the following URL:
<http://www.reliefweb.int/w/rwb.nsf/vLND>
(Report written by Gary Padgett; some material taken from TPC/NHC storm
report authored by Stacy Stewart)
HURRICANE JEANNE
(TC-11)
13 September - 2 October
--------------------------------------------
A. Storm History
----------------
The official TPC/NHC report on Hurricane Jeanne, authored by Miles
Lawrence and Hugh Cobb, is now available at the following URL:
<http://www.nhc.noaa.gov/2004jeanne.shtml?>
Jeanne was the seventh hurricane of the 2004 season and the sixth
major hurricane (MSW > 96 kts). (Karl, which formed after Jeanne,
became a major hurricane earlier than did Jeanne.) Jeanne formed from
a tropical wave of African origin and became a tropical depression on
the 13th just east of the Lesser Antilles. The depression moved into
the northeastern Caribbean where it became Tropical Storm Jeanne on
the 14th. The cyclone moved inland over southeastern Puerto Rico on
the 15th almost at hurricane intensity. After crossing Puerto Rico
Jeanne continued to intensify, reaching hurricane intensity over the
Mona Passage before striking the eastern tip of the Dominican Republic.
Jeanne moved slowly over the northern portion of the island of Hispaniola
on the 17th and weakened into a tropical depression. On 18 September,
after the center had moved northward back over the Atlantic, the original
LLCC moved westward away from the deep convection while a new center
formed well to the northeast of the old LLCC. Tropical Storm Jeanne
moved slowly through the Turks and Caicos Islands on the 19th, gradually
regaining its organization and strength. The slow movement of the
tropical storm contributed to torrential rainfall over Hispaniola. The
attendant flooding and mudslides led to thousands of fatalities in
Haiti.
The mid-level circulation from the remnants of Hurricane Ivan combined
with a shortwave trough in the westerlies and moved to the northeastern
U. S. coast where it eroded the ridge to the north of Jeanne. As a
result, Jeanne was left in a region with weak steering flow over the next
few days. From the 20th to the 24th Jeanne executed a large clockwise
loop a few hundred miles east of the northwestern Bahamas. The cyclone
regained hurricane intensity on the 20th and had become a Category 2
hurricane with 85-kt winds by 1200 UTC on the 22nd, but the intensity
leveled off and Jeanne weakened back to a Category 1 storm on the 24th
as it moved over its own previous track from a few days earlier and
encountered cooler waters caused by upwelling. As the storm moved away
from the cooler waters, it began to steadily re-intensify, becoming a
Category 2 hurricane once again at 1800 UTC on the 24th. Jeanne's
winds reached 100 kts at 25/1200 UTC as it was reaching Great Abaco
Island in the northwestern Bahamas. Jeanne followed a track across
Great Abaco and Grand Bahama Islands and to the eastern Florida coast
which was almost identical to that followed by Hurricane Frances three
weeks earlier.
Hurricane Jeanne made landfall at the southern end of Hutchinson
Island just east of Stuart at 0400 UTC on 26 September with peak winds
estimated at 105 kts over a very small area north of the center. The
slowly weakening storm then moved across central Florida, pretty much
right on top of Frances' track of three weeks earlier. The hurricane
weakened to a tropical storm at 26/1800 UTC while centered about 55 km
north of Tampa, Florida. In contrast to Frances, Jeanne's center did
not move back out over the northeastern Gulf of Mexico, although it
almost reached the coast in the Cedar Keys area. The weakening tropical
storm turned northward over Georgia and was downgraded to a tropical
depression on the 27th. The depression subsequently moved over the
Carolinas, Virginia and the Delmarva Peninsula before merging with a
frontal zone and losing tropical characteristics on the 29th while moving
eastward away from the U. S. mid-Atlantic coast.
B. Meteorological Observations
------------------------------
The highest sustained (1-min avg) surface wind reported in Florida
was 79 kts at the Melbourne NWS office. A reading of 69 kts was taken
on the north shore of Lake Okeechobee at 0515 UTC on the 26th. A C-MAN
station on Grand Bahama reported 77 kts at 26/0000 UTC when the center
was located about 35 nm northwest of the station. The highest wind gust
reported in Florida was 111 kts at Ft. Pierce Inlet, and a 106-kt gust
was reported from Vero Beach. Rainfalls of up to 200 mm accompanied
Jeanne as it moved across the Peninsula. A narrow band of 280-330 mm
was observed in the vicinity of the eyewall track over Osceola, Broward
and Indian River counties. A radar-estimated maximum of 280 mm was
observed over extreme northeastern Florida in Duval and Nassau counties.
Many more observations are available in the official storm report at
the link given above.
C. Damage and Casualties
------------------------
Press reports indicated that more than 3000 persons lost their lives
in Haiti due to flooding and mudslides, including nearly 2900 in the
coastal city of Gonaives. Some 200,000 people in the city lost their
homes, belongings and livelihoods. One death directly related to Jeanne
was reported in Puerto Rico, two in Florida, and one in South Carolina,
the latter due to a tornado. The total damage estimate in the U. S. has
been placed at $6.5 billion.
More articles concerning the destructive effects of Jeanne in the
Caribbean may be found at the following website:
<http://www.reliefweb.int/w/rwb.nsf/vLND>
(Report written by Gary Padgett; some material taken from TPC/NHC storm
report authored by Miles Lawrence and Hugh Cobb)
HURRICANE KARL
(TC-12)
16 - 26 September
-------------------------------------
The official TPC/NHC storm report on Hurricane Karl, authored by
Jack Beven, is available at the following URL:
<http://www.nhc.noaa.gov/2004karl.shtml?>
There is not a whole lot to say about Hurricane Karl. The storm
became an impressive Category 4 hurricane but, in stark contrast to
the preceding several hurricanes, pursued a harmless course northward
through the mid-Atlantic. The pre-Karl wave emerged from Africa on
13 September and had become organized enough to be classified as a
tropical depression by the 16th--the same day that destructive Hurricane
Ivan made landfall along the northern Gulf Coast. Tropical Storm Karl
was christened on the 17th, and had strengthened into a hurricane the
next day while moving west-northwestward. The cyclone became a major
hurricane (Category 3) early on the 19th, and reached its peak intensity
of 125 kts on 21 September. The hurricane had by this time turned
northward toward a weakness in the subtropical ridge, and on the 22nd
turned north-northeastward in response to a baroclinic trough developing
to the north. Karl weakened to 90 kts on the 22nd, apparently due to
an eyewall cycle, but rebounded to 110 kts on the 23rd. Following this
secondary peak in intensity, Karl began to weaken rather rapidly as it
began to transform into an extratropical cyclone. The former Category 4
hurricane had completed its transition into an extratropical cyclone
by early on the 25th a little over 500 nm east of Newfoundland. The
remnant extratropical LOW eventually reached Norway before being absorbed
by another LOW.
No damage or casualties are known to have resulted from Hurricane
Karl.
(Report written by Gary Padgett; some material taken TPC/NHC storm
report authored by Jack Beven)
HURRICANE LISA
(TC-13)
19 September - 3 October
--------------------------------------------
The official TPC/NHC report on Hurricane Lisa, authored by James
Franklin and David Roberts, is available at the following URL:
<http://www.nhc.noaa.gov/2004lisa.shtml?>
Like its predecessor, Hurricane Karl, Lisa moved northward through
the central Atlantic without ever affecting land. The progenitor of
Lisa was an African wave which departed the continent on 16 September.
The system gradually developed, becoming a tropical depression on the
19th when located about 450 nm west-southwest of the Cape Verde Islands.
The synoptic-scale environment was not particularly favorable for
strengthening. Hurricane Karl lay a few hundred miles to the west-
northwest and its outflow was impinging on the depression. Also, a
large, active tropical wave was located just a few hundred miles to the
southeast. Nonetheless, a very small core began to rapidly organize,
becoming Tropical Storm Lisa on the morning of the 20th. Just 18 hours
later, Lisa reached an initial peak intensity of 60 kts. However, over
the next couple of days the tropical storm weakened due to persistent
northerly shear. Meanwhile, the disturbance to the east continued to
approach Lisa, which had essentially stalled.
The two systems began to undergo a Fujiwhara interaction. Lisa turned
southward on the 22nd and then eastward the next day as convection from
the two systems gradually merged. Lisa weakened to a tropical depression
on the 23rd, but was nonetheless able to maintain a small but distinct
LLCC throughout its merger with the disturbance. A QuikScat image from
22 September clearly depicts the two circulations, and there are some
rain-flagged vectors of 40 kts within the circulation of the easternmost
disturbance. This system had been considered a good candidate for
tropical cyclone development, and had it not moved too close to Lisa
likely would have became Tropical Storm Matthew. Lisa completed a
cyclonic loop on the 24th, and on 25 September turned sharply northward
ahead of a deep mid to upper-level trough. As the shear abated Lisa
began to intensify again as it moved northward, almost reaching hurricane
intensity again on the 29th. On the 30th Lisa crossed over some cooler
water upwelled by Hurricane Karl and convection diminished, the winds
dropping to 45 kts, even though the eye feature remained distinct.
(Operationally, the MSW was dropped only to 55 kts during this time.)
On 1 October the tropical cyclone turned northeastward and accelerated
ahead of an approaching shortwave trough in the westerlies. Shear
lessened and Lisa re-intensified, even though it was over 25 C SSTs.
Early on 2 October cloud tops had cooled significantly and Dvorak
estimates reached 77 kts. Lisa became the season's ninth hurricane
at 0600 UTC on the 2nd when located about 625 nm southeast of Cape Race,
Newfoundland. Amazingly, at this time water temperatures beneath the
cyclone were around 23 C. After only about 12 hours, the cloud pattern
began to deteriorate rapidly and Lisa had lost tropical characteristics
by early on 3 October. A few hours later Lisa's remnants had been
absorbed into a frontal zone. Operationally, Lisa was upgraded briefly
to a hurricane for 6 hours on 1 October, but this was disallowed during
post-storm analysis.
No damage or casualties are known to have resulted from Tropical Storm
Lisa.
(Report written by Gary Padgett; some material taken from TPC/NHC storm
report authored by James Franklin and David Roberts.)
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for September: 1 hurricane
1 intense hurricane
NOTE!!! The Northeast Pacific basin will be covered in the third
installment of the September summary.
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for September: 5 tropical depressions **
2 tropical storms ++
1 typhoon
** - none of these were classified as tropical depression by JTWC; two
were treated as tropical depressions by JMA only; two others by
JMA and NMCC; and another by JMA and PAGASA
++ - one of these was not classified as a tropical storm by JTWC, but was
by several of the Asian TCWCs
NOTE!!! The Northwest Pacific basin will be covered in the second
installment of the September summary.
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for September: 1 active monsoon depression
1 tropical depression **
** - this system was not classified as a tropical depression by JTWC
NOTE!!! The North Indian Ocean basin will be covered in the third
installment of the September summary.
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for September: 1 tropical depression
NOTE!!! The Southwest Indian Ocean basin will be covered in the second
installment of the September summary.
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for September: 1 tropical cyclone of storm intensity
NOTE!!! The Northwest Australia/Southeast Indian Ocean region will be
covered in the second installment of the September summary.
*************************************************************************
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: 1 non-tropical depression
NOTE!!! The South Pacific basin will be covered in the third installment
of the September summary.
*************************************************************************
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.
*************************************************************************
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.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 2003 (2002-2003 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 2003 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2003 Atlantic
and Eastern North Pacific cyclones are now available, as well as
track charts and reports on storms from earlier years. Some of
the storm reports for 2004 cyclones are currently available as
well.
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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