[Index]
Monthly Global Tropical Cyclone Summary October 1998
[Summaries and Track Data] [Prepared by Gary Padgett]
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Cyclones
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Monthly Global Tropical Cyclone Summary October 1998 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
OCTOBER, 1998
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
SPECIAL NOTE: Another site where these summaries and track files are
archived is Weather Watchers Online, courtesy of Tom Berg. The URL
is: http://www.hcane.com/tropcl.html>.
Also, the website for the UK Meteorological Office contains much
information on tropical cyclones globally, including statistics for
storms on a monthly basis. The URL is:
http://www.met-office.gov.uk/sec2/sec2cyclone/sec2cyclone.html>
***********************************************************************
OCTOBER HIGHLIGHTS
--> Two hurricanes threaten Mexican Pacific Coast but neither
makes landfall
--> Two destructive typhoons slash across northern Philippines
--> Most intense Caribbean hurricane in ten years causes catastrophic
loss of life in Central America
***********************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for October: 2 hurricanes
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory. All
references to sustained winds imply a 1-min averaging period unless
otherwise noted.
ADDITIONAL INFORMATION ON HURRICANE GEORGES
A few weeks ago I received an e-mail from Juan Sebastian Lebron
Delgado in Puerto Rico containing additional information on the after-
math of Georges in Puerto Rico and the Dominican Republic. This
information came from the reputable newspaper _El Nuevo Dia_ (web
version at http://www.endi.com> ). Puerto Rico was devastated.
About 25,000 homes were totally destroyed with 65,000 partially
damaged. At least 2 persons were killed by collapsing roofs; many
others were swept away by rivers or mudslides but were still listed
as missing at the time of the report. Many of these were near
Arecibo, where el Rio Grande de Arecibo experienced an even bigger
flood than two years ago. The source region for the river
experienced an estimated 635 to 760 mm of rain. If substantiated,
this will eclipse the previous 24-hr rainfall record of 638 mm
recorded in association with Hurricane Hortense in 1996. (Hortense's
rainfall broke a record which had stood since the San Ciriaco
Hurricane of 1899, which killed 3369 in Puerto Rico.)
Five employees of a power company were killed while repairing lines.
The entire island was without power and it was estimated that it would
take 7 months to fully restore service. A wind gust of 150 kts was
measured "in the mountains", but the exact location wasn't given.
The storm surge height wasn't given, but the surge moved almost 1 km
inland in the cities of Humacao, Yabucoa, and Maunabo.
The number of fatalities in the Dominican Republic is still open to
debate. Some initial reports placed the toll above 2000, but the
newspaper contained an interview with the Dominican consul in Puerto
Rico, and the official was quoted as saying that probably several
hundred were killed but that 1000 may be a little high. One reason
that the Dominican Civil Defense was having trouble estimating the
number of dead is that many were buried in mass graves before the
authorities arrived in some of the more isolated areas. There was also
an unconfirmed report of a mudslide which had buried four villages,
killing 600. More than 600,000 homes were reported destroyed and
the total hurricane damage for the Dominican Republic was estimated at
$1.7 billion. The death toll for Haiti was placed near 300.
(A special thanks to Juan for sending along this information.)
Hurricane Lisa (TC #12)
5 - 9 October
------------------------
A strong tropical wave had been followed across the tropical
Atlantic for several days in early October. By 5 Oct the system had
run into some vertical shear several hundred miles east of the Lesser
Antilles and a fairly well-defined low-level center was exposed on the
west side of an area of deep convection. Around 1100 UTC an
observation of 45-kt winds was received from a drifting buoy. Based
on this report and the well-organized appearance of the circulation,
advisories were initiated on Tropical Storm Lisa at 2100 UTC. The
discussion noted that Lisa possibly had been a tropical storm for
18 hours or more. Initial intensity was set at 40 kts since it was
assumed the storm possibly had weakened some during the day. Lisa
became the third Atlantic tropical cyclone of the season to be named
on the first public advisory, the others being Earl and Jeanne. (Four
additional storms were named on the second advisory.)
The initial position of Lisa was about 725 nm east of the island
of Guadeloupe. The storm was expected to begin weakening as it
continued on a westward course into a region of even stronger shear;
however, Lisa rather quickly turned to the north and then northeast
in response to a major mid-tropospheric trough over the mid-Atlantic.
The storm remained in a sheared environment, but was moving with the
large-scale flow so the relative shear over the system was lessened.
Lisa moved rather slowly in a general north-northeasterly direction
on 6 Oct. The MSW was increased to 45 kts based on another report from
the drifting buoy still located in the convection southeast of the
center. The storm became better organized on the 7th as it accelerated
to the northeast, later turning back to the north. A drifting buoy
reported winds to 60 kts while satellite estimates were about 45 to 50
kts, so the MSW was increased to 50 kts at 07/1500 UTC. By the 8th
Lisa was moving northeast in excess of 20 kts ahead of a major trough
over the central Atlantic while the cloud pattern was gradually
becoming more defined with banding features, a CDO, and an eye trying
to form.
On 9 Oct the storm had turned to the north around a 500-mb cut-off
LOW which had formed to its west and had accelerated to nearly 40 kts.
Morning satellite pictures showed Lisa to still be separated from the
frontal LOW and T-numbers were 4.0, so the cyclone was upgraded to a
minimal hurricane with 65-kt winds as it passed approximately 350 nm
west of the northernmost Azores. Lisa continued racing northward and
was declared extratropical by 2100 UTC several hundred miles east of
Newfoundland.
Hurricane Mitch (TC #13)
22 October - 8 November
-------------------------
From the depths of the Caribbean Sea came the strongest hurricane to
roam the Atlantic basin in 10 years, and the first to even reach
Category 5 status on the Saffir/Simpson scale in 9 years. And after
reaching its peak intensity, Hurricane Mitch was responsible for one
of the greatest catastrophes to strike the North and Central American
region since records have been kept. At its peak mighty Hurricane
Mitch had an estimated MSW of 155 kts with an attendant pressure of
905 mb as measured by a U. S. Air Force Reserves Hurricane Hunter
plane. That value is the fourth lowest central pressure measured in an
Atlantic basin hurricane. A 905-mb central pressure was also measured
in Hurricane Camille in August, 1969, in the central Gulf of Mexico.
It is also the lowest pressure ever measured in an October cyclone.
Lower Atlantic basin pressures include:
(a) 899 mb in Hurricane Allen, August, 1980, Northwest Caribbean
(b) 892 mb in the famous Labor Day Hurricane, September, 1935,
Lower Matecumbe Key in the Florida Keys
(c) 888 mb in Hurricane Gilbert, September, 1988, Northwest
Caribbean
A tropical wave moved westward across the tropical Atlantic and
southern Caribbean in mid-October but did not show significant signs
of developing until around 20 Oct. The wave became better organized
on 21 Oct and a reconnaissance flight in the evening found that a
tropical depression had developed. A central pressure of 1001 mb in
a tight center and flight-level winds of 39 kts indicated that the
depression was already near tropical storm strength. The initial
advisory located the depression's center about 320 nm south of
Kingston, Jamaica.
The system moved somewhat erratically for a couple of days,
apparently drifting in a small cyclonic loop. A Hurricane Hunter
plane found 51-kt winds at the 450 m flight level on 22 Oct so the
depression was upgraded to Tropical Storm Mitch with 40-kt winds at
2100 UTC. The storm was centered about 360 nm south of Kingston at
this time. Mitch was well-organized and its MSW increased to 50 kts
by 23/0600 UTC, but as the day progressed, the storm was hit with some
unexpected westerly shear. However, Mitch held its own and by late
on the 23rd, the shear had lessened and deep convection had returned
to the central area of the storm. By early on 24 Oct a ragged eye
had begun to appear and T-numbers had reached 4.0 and 4.5. The
Hurricane Hunters arrived on the scene around 0600 UTC and found
a central pressure of 992 mb, winds of 64 kts at 850 mb and hints of
an eye; two hours later they found a pressure of 988 mb, winds of 91
kts at 850 mb and a partial eyewall. Mitch was upgraded to a
hurricane with a MSW of 80 kts at 0900 UTC. At this time the storm
was located about 250 nm south of Kingston and was moving slowly
northward.
By afternoon the pressure had fallen to 976 mb and the MSW had
increased to 90 kts. Mitch was displaying a well-defined eye and
excellent outflow was present in all quadrants. The forecast from
TPC/NHC at this time was calling for Mitch to reach 120 kts by 36
hours. Twenty-four hours later a reconnaissance flight found that
the pressure had dropped 52 mb to 924 mb at 1800 UTC on 25 Oct.
A flight-level (3000 m) wind of 155 kts was reported and the surface
MSW was increased to 130 kts. Mitch at this time had turned to more
of a westerly or west-northwesterly track. An early morning
reconnaissance flight on 26 Oct found a 10-nm diameter eye with a
central pressure of 923 mb. The eye was embedded within a symmetrical
ring of very cold cloud tops--the signature of a very intense tropical
cyclone.
Mitch continued on a slow west-northwesterly track in the direction
of tiny Swan Island in the Northwest Caribbean. The central pressure
continued to fall and a Hurricane Hunter flight around midday on the
26th measured 906 mb, and a couple of hours later the 905 mb reading
was obtained. A GPS dropwindsonde measured a sustained wind of 173 kts
at an elevation of 150 m, so the MSW was increased to 155 kts in the
2100 UTC advisory. At its peak intensity Hurricane Mitch was located
about 40 nm southeast of Swan Island. The hurricane passed over or
very near the island, but the author has not learned of any reports
from the island. (Coincidentally, Swan Island was struck by another
Category 5 hurricane over 40 years ago. Around midday on 27 Sep 1955,
the eye of Hurricane Janet passed directly over the island. A very
interesting eyewitness account of Janet can be found in Dunn and
Miller's classic book _Atlantic Hurricanes_. Twelve hours after
striking Swan Island, Janet passed over Chetumal, Mexico, which lies
probably 30 nm or so inland with a large bay and peninsula separating
it from the open Caribbean. An anemometer at the Chetumal Airport
was registering 175 mph (152 kts) when it collapsed. Eyewitnesses
reported that the wind continued to increase a goodly amount after
the instrument was destroyed.)
After peaking in intensity Mitch began to steadily weaken. The
hurricane moved very slowly to the southwest and stalled for about 24
hours just off the north Honduran coast near the islands of Roatan
and Guanaja. Then the storm resumed a very slow drift to the south
and had moved inland over Honduras by 1800 UTC on 29 Oct. The MSW
was still estimated at 155 kts at 0600 UTC on the 27th; 24 hours later
it had fallen to 115 kts and the pressure had risen to 942 mb; by
29/0600 UTC the pressure had risen to 979 mb and the MSW had dropped
to 75 kts. Mitch was downgraded to a tropical storm at 2100 UTC
and the reported MSW had been further decreased to 35 kts by 30/1500
UTC, but was increased back to 50 kts at 2100 UTC on the 30th based
on a report of 49 kts from Roatan Island. A report of 70 kts from
Puerto Barrios was believed to be the result of a funneling effect from
nearby mountains.
Mitch was downgraded to a tropical depression at 1500 UTC on 31 Oct
since there had been no reports of 34-kt winds during the past 12 hours
and land observations indicated 10-20 kt winds. A 1500 UTC observation
from ship C6HH3 did report winds of 54 kts in a band of strong
thunderstorms well removed from the center of Mitch. Forecasters at
TPC/NHC learned from the Belize Meteorological Service that the
funneling effect of the local mountains indeed often leads to rather
strong winds in the region. The weakening system drifted south across
Honduras, then turned gradually westward and moved across Guatemala.
By the afternoon of 1 Nov surface data showed little evidence of a
circulation, and an analysis of microwave imagery by the Air Force
Global Weather Agency revealed no low-level center, so advisories on
Mitch were discontinued. The weak LOW by this time had reached
extreme southeastern Mexico.
The remnants of Mitch moved northward on 2 and 3 Nov and moved out
over the southeastern Bay of Campeche. Satellite imagery suggested
that the LOW was strengthening and a reconnaissance flight was
dispatched to the area around midday on the 3rd. The Hurricane
Hunters found a 997-mb central pressure and winds to 50 kts near 450 m,
so the system was re-classified as Tropical Storm Mitch. Mitch
was located just off the west coast of the Yucatan Peninsula moving
northeastward, and within a few hours was inland and had been down-
graded to a tropical depression once more. By early on 4 Nov the
system was emerging back out into the southern Gulf of Mexico. Ship
and surface reports indicated that Mitch was not completely tropical
with minimal central convection and relatively light winds within
about 100 nm of the center, but tropical storm force winds were
occurring in a convective band between 200 and 300 nm southeast to
northeast of the center. To accommodate this and to simplify the
warnings, Mitch was upgraded again to a tropical storm at 1500 UTC.
Mitch accelerated quite rapidly toward the northeast and made
landfall near Ft. Myers, Florida, around 1200 UTC on 5 Nov. The storm
quickly crossed the peninsula and exited into the Atlantic within a
few hours. MSW increased to 55 kts with the central pressure falling
to 990 mb before Mitch made its final landfall in Florida. As Mitch
was making landfall, a Hurricane Hunter flight flew a "shore patrol"
around the southern end of the peninsula. An extrapolated pressure
of 988 mb was found just west of the center, and 73-kt winds were
reported at the 850 m flight level just east of Biscayne Bay. Fowey
Rocks reported a 10-min avg wind of 51 kts with a peak gust of 63 kts
at 1300 UTC.
Mitch was more of a hybrid system during this time, but did retain
some tropical characteristics as it crossed over Florida. Shortly
after passing into the Atlantic near Jupiter the storm was declared
extratropical. The extratropical storm continued rapidly
northeastward across the Atlantic, passing north of Bermuda and south
of Newfoundland. The system appeared to deepen significantly on the
7th as it was racing across the North Atlantic well southeast of
Newfoundland. Press reports indicated that the gusty winds of Mitch
caused widely scattered damage across the southern part of the Florida
peninsula and the Keys. Two deaths were attributed to the storm in
Florida.
However, as most of the world knows, the torrential rains of Mitch
in Central America unleashed one of the greatest disasters on record in
the Western Hemisphere. The highest actual death toll noted by the
author was 11,000 with an additional 18,000 missing. A report on
12 Nov by the United Nations' Office for the Coordination of
Humanitarian Affairs (OCHA) listed 9346 dead with 9694 still missing.
Hardest hit was Honduras with 7000+ fatalities; Nicaragua was next
with 1849 deaths; Guatemala and El Salvador had 258 and 239 fatalities,
respectively. One of the single deadliest events was a mammoth
mudslide on the flank of the Casitas volcano in northwestern Nicaragua.
Many villages were swept away with the loss of well over 1000 lives.
The actual number of deaths will probably never be known, but Hurricane
Mitch will likely go on record as the second deadliest Atlantic
hurricane in history, exceeded only by the Great Hurricane of October,
1780, which swept through the Lesser Antilles with a loss of more than
22,000 lives.
The author has seen very few actual rainfall amounts from Central
America. One press article mentioned rates of up to 100 mm per hour
in some spots. I do have some rainfall data from southern Honduras
near the city of Choluteca. This was supplied by Mr. Jon Hellin of
the UK, who has been in Honduras working on a PhD thesis in soil and
water conservation in association with the Corporacion Hondurena de
Desarrollo Forestal. Mr. Hellin's site was 11 km from Choluteca, which
is in the southern part of the country near the Pacific coast. The
actual coordinates of the trial site are 87 deg 04 min West, 13 deg
17 min North--altitude 100 m. The site was destroyed by the heavy
rains but Jon was able to salvage some rainfall measurements which he
thought might be useful to the meteorological community. From 28 Oct
through 3 Nov the total amount logged was 933 mm. The greatest
amounts were recorded on 30 and 31 Oct with 245.8 mm and 393.8 mm,
respectively. No doubt amounts farther north in the more mountainous
regions were much higher.
Damage to the infrastructure of Honduras is almost unimaginable.
Losses to agriculture are also astounding. A press report quoted the
President of Honduras as saying that "the country is semi-destroyed".
Transportation is very difficult because a high percentage of the
nations' bridges were destroyed. A recent press article noted by
the author mentions that now more lives are threatened by diseases,
with cases of cholera, leptospirosis, and dengue on the rise.
I assume that most readers of these summaries have access to the
Internet, so rather than try to summarize more bits of pieces of this
great tragedy in Central America, I am listing some websites where more
information on the aftermath of Mitch can be found.
(1) http://www.usatoday.com/weather/worldwea.htm>
(2) http://www.disastercenter.com/hurricm.htm>
(3) http://wwwnotes.reliefweb.int>
(4) http://www.ncdc.noaa.gov/ol/reports/mitch/mitch.htm>
(5) http://www.gbm.hn>
Gale Center in Gulf Of Mexico
21 - 24 October
-----------------------------
Although not a tropical cyclone, an unusual weather situation
developed in the Bay of Campeche area about the same time that Mitch
was forming in the Southwestern Caribbean. A weak tropical LOW had
formed on a tropical wave which traversed the Caribbean and moved
across the Yucatan Peninsula into the Bay of Campeche. At the same
time a fairly strong cold front had pushed out into the Gulf and
stretched from the extreme southwestern Gulf northeastward toward
Northwest Florida. By 21 Oct the LOW had shown some signs of increased
organization and a Hurricane Hunter flight was dispatched to
investigate the area. The plane could find no well-defined circulation
center nor pressure center.
On the 22nd the system's organization was about the same but winds
to 35 kts and occasionally 40 kts were being reported across the Bay of
Campeche, mainly west of the LOW center. These gales were possibly
related to a cold air surge associated with the front. By late on the
22nd thunderstorms were beginning to increase nearer to the low-level
center of the system.
Early on 23 Oct the LOW was still showing more characteristics of a
tropical system even though it was interacting with the front to some
degree. A reconnaissance flight reached the area about midday and
found that the center had moved southward and was located just inland
in Mexico near 93.3 W. Maximum flight-level winds (300 m) associated
with the depression were near 30 kts; however, the plane encountered
the cold front at 19 N, 94.5 W and found flight-level winds of 70 kts
north of the front. The center of the LOW remained inland and the
system slowly weakened over the next couple of days.
I discussed this system with Jack Beven (some of the above infor-
mation was supplied by Jack) and he feels that it could be classed
as some sort of hybrid system. The gales, as stated above, were
likely caused by a cold air surge west of the LOW and which got
pulled eastward along the southern periphery. There was a fairly
significant amount of convection near the supposed circulation center
early on 23 Oct, but there is uncertainty regarding the strength of
the winds near the center at that time. Jack informed me he plans
to study the system in greater detail as time permits to see if it
might qualify as a subtropical storm or (much less likely) a tropical
storm or depression.
***********************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for October: 1 tropical depression
3 hurricanes
NOTE: Much of the information presented below was obtained from the
TPC/NHC discussion bulletins issued with every regular advisory (CPHC
for locations west of 140W.) All references to sustained winds imply
a 1-min averaging period unless otherwise noted.
Tropical Depression (TC-12E)
1 - 3 October
-----------------------------
The first tropical depression to form in the Northeast Pacific basin
in almost a month turned out to be a rather weak, diffuse system. The
depression remained essentially quasi-stationary throughout the period
of its warning status approximately 150 nm south-southeast of Cabo San
Lucas on the southern tip of the Baja California peninsula. The track
coordinates seem to depict a north-south movement up and down the
109th meridian (west), but this appears to be due to re-locations of
the center. Depression advisories were initiated at 2100 UTC on 1 Oct
after a cluster of deep convection had persisted for most of the day.
The system was initially forecast to intensify into a moderately strong
tropical storm, but this failed to materialize.
The center was re-located about 70 nm to the north and east of the
previous position at 02/0900 UTC based on a report from a ship (C6LF9).
However, the first visible pictures that morning suggested that the
low-level center was located over 100 nm to the south--a position which
would violate the 0600 UTC observation of a southwest wind from the
ship. The 1500 UTC advisory re-located the center back to the south
to a position almost 200 nm south-southeast of Cabo San Lucas. A ship
reported 33-kt winds just northeast of the center at 1500 UTC,
confirming that the depression remained below tropical storm strength.
Late on the 2nd the system appeared to be weakening and the final
advisory was issued at 03/0300 UTC, placing the weak center roughly
100 nm south-southeast of Cabo San Lucas.
Hurricane Kay (TC-13E)
13 - 17 October
-----------------------
Hurricane Kay was a small, short-lived hurricane which developed
quickly and then died quickly several hundred miles southwest of the
Mexican coast. A disturbance, initially associated with the ITCZ, had
been tracked for several days. By the 12th the system had lifted
northward and had become detached from the ITCZ. Increasing
organization during the day led to the first depression advisory being
issued at 13/0300 UTC, placing the center about 600 nm southwest of
Cabo San Lucas. Twelve hours later the depression had intensified
rapidly and the system was upgraded to Tropical Storm Kay with 60-kt
MSW. A warm spot was evident in infrared satellite imagery, and by
the afternoon of 13 Oct a small eye had formed and persisted for
several hours. Dvorak classifications had reached T=4.0 so Kay was
upgraded to a hurricane. Kay was a small cyclone as the radius of
hurricane force winds was estimated to be only 25 nm while gales
reached out 60 nm from the center. Peak intensity of 65-kt MSW and
estimated central pressure of 987 mb was reached at 13/1800 UTC.
Just as Kay had intensified with great rapidity, so also it weakened
just about as quickly. By the morning of the 14th the deep convection
had essentially vanished and Kay was downgraded to a tropical storm
at 0900 UTC, and further downgraded to a depression at 15/0300 UTC.
During its initial developmental and hurricane stages, Kay drifted very
slowly to the west and west-southwest. As it began to weaken, the
storm began to move more to the south-southwest. For the next couple
of days enough intermittent convection would fire up to justify
continuing advisories on the system. The depression center drifted
south-southwest to a point about 900 nm southwest of Cabo San Lucas,
then turned more to the south-southeast. The final advisory on Kay
was written at 0300 UTC on 17 Oct and placed the weak low-level center
only about 300 nm southwest of its point of origin.
Hurricane Lester (TC-14E)
15 - 26 October
--------------------------
A tropical disturbance southeast of the Gulf of Tehuantepec was
getting better organized on 14 Oct as convective banding became better
defined south and east of the center and deep convection increased
near the low-level center. Upper-level outflow was also well
established, so depression advisories were initiated at 0300 UTC
on 15 Oct. The center of the new depression was located approximately
375 nm southeast of Salina Cruz, Mexico. The system initially moved
on a general northwesterly track--a little erratically--toward the
Mexican coast in the western Gulf of Tehuantepec region. The
depression was upgraded to Tropical Storm Lester at 16/0300 UTC with
a MSW of 45 kts. Lester was centered at this time about 225 nm
southeast of Salina Cruz.
The storm steadily intensified, and a U. S. Air Force Hurricane
Hunter flight into the storm on the afternoon of the 16th found flight-
level winds of 70 kts and a central pressure of 992 mb. A GPS
dropwindsonde reported a maximum wind of 80 kts with 71 kts at the
surface. An eye had also become visible in satellite imagery, so
Lester was upgraded to a hurricane at 2100 UTC located about 125 nm
south-southeast of Salina Cruz.
Since Hurricane Lester was forecast to move quite close to Mexico,
watches and warnings were issued for a portion of the coastline. This
threat, however, failed to materialize as the hurricane swung to more
of a west-northwesterly, and then westerly, course roughly parallel to
the coastline. A reconnaissance flight on the 17th measured a central
pressure of 973 mb, and another flight on the 18th measured a peak
flight-level wind of 98 kts with the pressure also 973 mb. A GPS
dropwindsonde measured winds of 85 kts near the surface. Lester at
this time had a circular eye 15 nm in diameter which was imbedded
in a circular CDO with convective tops of -70 to -80 deg C.
Estimated MSW reached 90 kts on the 18th, but Lester appeared to
weaken slightly on 19 Oct as the outflow was impeded somewhat in the
northeastern quadrant due to the effects of a mid- to upper-level LOW
over northern Guatemala. The storm passed about 165 nm south of
Acapulco around 0600 UTC on the 19th with the MSW estimated at 85 kts.
After weakening to 80 kts by 1800 UTC, Lester began to intensify once
more with the MSW reaching its estimated peak value of 100 kts (with
a central pressure of 960 mb) at 22/0600 UTC. The hurricane was
centered at this time about 300 nm southwest of Manzanillo.
Lester had been moving on a west-northwesterly course for the
previous three days, but as it reached its peak intensity, the storm
came to a virtual standstill. By early on 23 Oct the amount of
convection had diminished significantly and Lester began to weaken
rather rapidly. One factor leading to the weakening may have been
upwelling of cooler waters due to the very slow movement. Lester
was downgraded to a tropical storm at 23/1500 UTC. The weakening
cyclone moved south-southwestward on 23 and 24 Oct to a point about
400 nm southwest of Manzanillo, then resumed a west-northwestward
motion.
By the morning of the 24th Dvorak estimates were down to 35 kts,
but a burst of convection appeared over the center, so the MSW was
left at 45 kts. These bursts of central convection continued to
erupt through the morning of 25 Oct, so Lester was not downgraded
to a depression until 26/0300 UTC. The system continued to weaken
as southwesterly shear increased, and the final advisory at 1500 UTC
on the 26th placed the dissipating center about 450 nm southwest
of Cabo San Lucas.
While Hurricane Lester approached close enough to the Mexican coast
for peripheral effects to have been felt, the author has not located
any reports of casualties or significant damage due to this hurricane.
Hurricane Madeline (TC-15E)
16 - 20 October
----------------------------
Depression advisories were initiated at 16/0900 UTC on a disturbance
located about 200 nm west of Manzanillo. During the morning a very
large CDO feature, with core area tops less than -80 deg C, developed
over the center. Dvorak classifications were up to T=2.5, so the
depression was upgraded to Tropical Storm Madeline at 1500 UTC with
the MSW set at 45 kts. At around 1800 UTC ship 3FMH7 reported 50-kt
winds at a location about 40 nm northeast of the center, so the MSW
was increased to 55 kts in the next advisory. After this initial
blow-up, however, the convection became somewhat limited and Madeline's
intensity leveled off for the time being.
Madeline moved on a slow northwesterly course toward the Mexican
coast and gradually turned to a more northerly track. By the morning
of 17 Oct satellite pictures showed deep convection only on the western
side of the center, but there were also hints of an eye developing.
By afternoon the deep convection was wrapping 2/3 of the way around the
center and T-numbers had reached 4.0 from TAFB and SAB. A Hurricane
Hunter reconnaissance flight found a central pressure of 989 mb and
peak flight-level winds of 70 kts on the southwest side; therefore,
Madeline was upgraded to a 65-kt hurricane about 200 nm south of
Mazatlan at 2100 UTC. The Commander of the reconnaissance flight
made the comment that vertical motions were giving them quite a bumpy
ride!
On the morning of the 18th deep convection was more evenly
distributed but the coldest tops (-80 deg C) were to be found only
over the southern semi-circle. Outflow was well-established on the
western side but restricted on the east. An early-evening
reconnaissance flight found a closed eye 15 nm in diameter with a
central pressure of 982 mb. A GPS dropwindsonde reported surface winds
of 73 kts while the peak flight-level wind found was 76 kts. The MSW
was increased to its peak value of 75 kts at 2100 UTC with Madeline
located at this time about 150 nm south of Mazatlan. A slightly
lower pressure of 980 mb was measured on a subsequent pass through
the storm and was in close agreement with satellite estimates of 979 mb
a few hours later.
During the late afternoon and evening of 18 Oct Hurricane Madeline
moved through the Islas Tres Marias, located off the Mexican coast
and roughly 120 nm south of Mazatlan. About this time Madeline began
to be affected by strong southerly shear which caused the hurricane
to collapse with extreme rapidity. At 19/0000 UTC Madeline was a
75-kt hurricane with a 979-mb central pressure (confirmed by a
reconnaissance flight); 24 hours later the system was a rapidly
dissipating depression with only 20-kt winds. After passing through
the Islas Tres Marias the rapidly weakening cyclone turned to the
northwest, and the final advisory placed the low-level center in the
mouth of the Gulf of California a little less than 100 nm west of
Mazatlan.
The large areal extent and intensity of the initial convective
blow-up, coupled with model projections of a landfall along the Mexican
coast, led to a great concern that a major rainfall event for the
mountainous areas of Mexico could be shaping up, but fortunately this
threat failed to materialize. While Madeline moved quite close to the
Mexican mainland and passed over the small Islas Tres Marias, the
author has not located any reports of damage or casualties due to the
storm.
***********************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for October: 3 tropical depressions
1 tropical storm
2 supertyphoons
NOTE: Most of the information on each cyclone's history presented in
the narrative will be based upon JTWC's advisories, and references to
winds should be understood as a 1-min avg MSW unless otherwise noted.
However, in the accompanying tracking document I have made comparisons
of coordinates with JMA (Japan) and the Philippines (PAGASA) when their
positions differed from JTWC's by usually 40-50 nm or more. Also, as
announced earlier in a separate posting, a column of 10-min avg MSW
is included--the values being obtained from either PAGASA's or JMA's
advisories. A special thanks to Michael V. Padua, owner of the Typhoon
'98 webpage, for sending me the PAGASA tracks. Also some information,
primarily on the pre-depression stages of the various cyclones, was
taken from the Monthly Report of the RSMC, Darwin, Northern Territory,
Australia. A special thanks to Peter Bate for forwarding that report
to me.
In the title line for each storm I plan to reference all the cyclone
names/numbers I have available: JTWC's depression number and name (if
any), JMA's tropical storm numeric designator, and PAGASA's name for
systems forming in or passing through their area of responsibility.
Tropical Depression (TC-15W)
2 - 6 October
-----------------------------
JMA was the first warning center to begin issuing advisories on this
system. The depression was first located in the South China Sea about
650 nm south-southwest of Hong Kong at 0000 UTC on 2 Oct. The system
moved slowly and somewhat erratically to the north and east. JTWC
issued a Formation Alert at 02/0700 UTC when surface observations
indicated a large circulation with 20-kt winds along the periphery.
The first JTWC warning at 0600 UTC on 3 Oct placed the center about
450 nm south of Hong Kong, but the next advisory re-located the center
about 60 nm farther to the west based on satellite analysis and reports
from Xisha (WMO 59981) and Sanhu (WMO 59985) islands.
Convection remained concentrated along the periphery of the circu-
lation, mainly on the northeastern and southwestern sides. The system
moved generally west-northwestward, passed south of Hainan Island, and
moved into Vietnam after 1200 UTC on 5 Oct. The final advisory placed
the center inland about 100 nm southwest of Hanoi at 06/1200 UTC.
Tropical Depression (TC-16W)
5 - 7 October
-----------------------------
The second tropical depression in October formed from a vortmax in
the monsoon trough east-northeast of Taiwan. The initial advisory
at 0000 UTC on 5 Oct located the center about 75 nm southeast of
Taipei. The depression remained essentially stationary for the next
two days just east of northern Taiwan. The system was quite weak with
Dvorak T-numbers generally only around 1.0, implying a MSW of 25 kts.
The depression was stuck between one subtropical ridge to the east and
another one to the west over southern China.
By 07/0600 UTC the system was beginning to merge with a front to
the north as it moved east-northeastward away from Taiwan. By 1800
UTC almost all the convection had been sheared away to the east and
the final warning placed the weak low-level center about 165 nm west-
southwest of Okinawa.
Tropical Depression (TC-17W)
6 - 7 October
-----------------------------
The third depression to form in October was a weak, short-lived
system of high-latitude origin, and possibly may not have been fully
tropical. JMA did not issue any RSMC advisories on this system--it
was mentioned in their high seas Warning and Summary bulletins as
simply a low-pressure area. The depression began as an exposed low-
level circulation in an area of considerable vertical shear. JTWC
initiated warnings primarily because of a ship report of 30-kt winds.
At 06/0000 UTC the center was placed about 250 nm east-southeast of
Shanghai, and drifted very slowly northeastward during the next 24
hours. Six hours later the center was becoming elongated and the
depression appeared weaker. By 0000 UTC on the 7th the system was
located less than 50 nm from its point of origin and had lost its low-
level organization due to the passage of a weak front.
Supertyphoon Zeb/Iliang (TC-18W / TY 9810)
9 - 19 October
-------------------------------------------
What was to become the Northwest Pacific basin's most intense
tropical cyclone so far this year had its beginnings as a weak LOW in
the monsoon trough to the south of the Marianas. JTWC issued the
first depression advisory at 09/1800 UTC, placing the center of the
system about 300 nm southwest of Guam. The second warning re-located
the depression to the north somewhat, then the system began to move
steadily to the west. The depression was christened Tropical Storm
Zeb at 1200 UTC on 10 Oct about 300 nm northeast of Palau. Continuing
on a westward track Zeb became a typhoon at 12/0000 UTC when the storm
was centered about 250 nm northwest of Palau. The appearance of a
banding-type eye was the basis for upgrading the storm to typhoon
intensity.
About the time that typhoon intensity was attained Zeb began to
track more to the west-northwest. The storm also deepened rapidly
on 12 and 13 Oct, increasing from a 60-kt tropical storm at 1800 UTC
on 11 Oct to a 150-kt supertyphoon at 13/0000 UTC located about 400 nm
east of Manila. The typhoon, which had been named Iliang by
PAGASA, reached its estimated peak MSW of 155 kts at 1200 UTC on the
13th and maintained that intensity until landfall on Luzon. (JMA's
10-min MSW only reached 110 kts, but PAGASA's 10-min MSW estimate was
130 kts during the times when JTWC was reporting 155 kts 1-min MSW.)
At its peak Zeb/Iliang was a fairly large typhoon with 100-kt and
50-kt winds extending out from the center 50 nm and 100 nm,
respectively, while gales covered an area 500 nm in diameter.
Typhoon Iliang, still moving on a west-northwesterly course, entered
the island of Luzon east of the city of Ilagan. The storm passed near
Tuguegarao, then turned to a more north-northwesterly course and moved
over the northern coast back out into the Luzon Strait. The storm's
MSW had diminished to 85 kts while over the island and the storm did
not intensify to any significant degree after reaching the ocean again.
After exiting Luzon Zeb/Iliang turned north and then north-northeast,
moving very close to the east coast of Taiwan. By 15/0600 UTC the
forward speed increased significantly as Zeb was influenced by a ridge
to the east and southeast and a trough to the north. JMA downgraded the
system to a tropical storm at 0000 UTC on 16 Oct, but JTWC maintained
typhoon intensity for another 24 hours. Zeb's center passed about
75 nm east of Taipei around 16/0600 UTC with an estimated 85-kt MSW.
The typhoon had briefly re-intensified slightly about this time due
to a relaxation in upper-level shear.
Zeb continued to weaken as it accelerated toward Japan, being
downgraded to a tropical storm at 0600 UTC on the 17th when centered
a short distance south-southwest of Kyushu. The storm crossed over
extreme southern Kyushu, western portions of Shikoku, and thence
across western Honshu, passing west of Kyoto near Okayama. Zeb exited
into the Sea of Japan and was declared extratropical by 18/0600 UTC
as it merged with a frontal boundary. The extratropical remnants
of Zeb crossed Hokkaido, moved up into the Sea of Okhotsk, crossed
the Kamchatka Peninsula and moved into the Bering Sea.
The highest death toll in the Philippines from Zeb/Iliang noted by
the author was 83. One press article on the web mentioned 31 deaths
from Zeb in Taiwan and 12 in Japan. On Luzon losses to agriculture
and the infrastructure were quite severe, amounting to nearly a billion
Philippine dollars. In the Ilocos Region and Cagayan Valley, 181,630
metric tons of rice worth $384.2 million were destroyed. The mountain
resort town of Baguio measured 994.6 mm of rain--eight times the amount
recorded in association with Typhoon Gading (Vicki) in September.
Portions of the town were under 9 m of water.
The following websites contain more detailed information on the
effects of Typhoon Iliang in the Philippines:
(1) http://www.inquirer.net/issues/oct98/oct18/news/news_4.htm>
(2) http://www.inquirer.net/issues/oct98/oct16/news/news_2.htm>
Tropical Storm Alex (TC-19W)
11 - 12 October
-----------------------------
Tropical Storm Alex was a tiny tropical cyclone which formed within
the inflow into the much larger and strengthening Tropical Storm Zeb.
The small LOW was upgraded directly to Tropical Storm Alex based on an
11/1955 UTC observation from Rota of 40-kt sustained winds; and also
a report from Saipan at 1855 UTC of 25-kt winds. The initial position
was about 55 nm just east of due north of Guam at 0000 UTC on 11 Oct.
Gales were estimated to extend out only 30 nm from the center.
An amended warning was issued three hours later re-locating the
center of Alex about 90 nm to the west. This was based on visible
satellite imagery and radar observations. Alex was moving west-
northwestward at 21 kts and was located only about 430 nm east-
northeast of Zeb's center. The small storm was maintaining sustained
deep convection along with a well-organized low-level pattern.
However, the shear associated with Zeb increased and Alex was
downgraded to a depression at 12/0000 UTC, although it still managed
to produce some deep central convection. By 0600 UTC Alex was passing
about 400 nm due north of Zeb's center and was moving west at 33 kts.
By 1800 UTC a low-level center was no longer discernible and the weak
residual LOW was esimated to be about 200 nm west-northwest of Zeb
and moving southwest at 40 kts.
Supertyphoon Babs/Loleng (TC-20W / TY 9811)
14 - 27 October
--------------------------------------------
The second supertyphoon of the month formed on the heels of the
first and struck the island of Luzon only about 100 nm south of where
Supertyphoon Zeb/Iliang had made landfall. JTWC issued a Formation
Alert at 2330 UTC on 13 Oct, and the first depression warning was
issued at 14/0600 UTC, locating the weak center about 400 nm west-
southwest of Guam. The system was upgraded to Tropical Storm Babs
24 hours later about 275 nm north of Palau. Babs moved on a westerly
course until around 1800 UTC on 17 Oct, when it essentially stalled
about 300 nm east of the central Philippines. For the next couple
of days Babs drifted slowly in a general southerly direction.
During its first few days of existence Babs' development was
hampered by the outflow from Typhoon Zeb. The storm strengthened some
on the 16th, but weakened significantly on the 17th as its low-level
center became exposed on the north side of the deepest convection. An
upper-level LOW to the northeast also contributed some to the shear.
By late on 18 Oct the inhibiting shear had lessened and Babs reached
typhoon intensity at 0000 UTC on 19 Oct. A ship (JCQU) reported
a 10-min sustained wind of 52 kts at 19/0000 UTC, but the ship's
relationship to the center is unknown. The storm was still quasi-
stationary at this time, but by late on the 19th had begun to move
on a slow west-northwesterly course.
By 0000 UTC on 20 Oct Babs (christened Loleng by PAGASA) had rapidly
intensified to a MSW of 115 kts with an 8-nm diameter cloud-filled eye.
Twelve hours later Babs/Loleng reached its peak intensity of 135 kts
1-min MSW (105 kts 10-min MSW). 100-kt winds extended outward 20 nm
from the 13-nm diameter eye while gales reached out 180 nm to the
northeast. Six hours later the radius of 100-kt winds had expanded
to 40 nm.
The eye of Typhoon Loleng passed directly over Catanduanes Island
around 1200 UTC on 21 Oct. The weather station at Virac (WMO 98446)
measured a minimum pressure of 927.9 mb in the eye with peak gusts
of 140 kts. The typhoon continued moving west-northwestward along
the coast of southeastern Luzon, passing very near Daet (WMO 98440)
which measured a minimum pressure of 963.5 mb with a MSW of 70 kts
(10-min) and peak gusts to 100 kts. Michael Padua of Naga City
(owner of the Typhoon '98 webpage) sent me some observations he made
at a location about 35 km north-northeast of Naga City. He reported
a minimum pressure of 976 mb and peak gusts of 59 kts.
Typhoon Loleng's eye then moved over Lamon Bay, over Polillo
Island, and into the eastern coast of Luzon approximately 25 nm south
of Baler around 1800 UTC on 22 Oct. The synoptic station at Baler
(WMO 98333) recorded a minimum pressure of 984.7 mb, a 10-min MSW of
60 kts, and a peak gust of 104 kts. The center of the storm crossed
central Luzon, passing around 40 nm north of Manila and exiting in the
Lingayen Gulf region near Dagupan.
After crossing into the South China Sea, Babs/Loleng continued on a
northwestward track for a couple of days, gradually recurving to the
north and then northeast, and accelerating as a trough to the north
modified the subtropical ridge which had been guiding the storm. The
westernmost point of Babs' track was reached at 1200 UTC on 25 Oct when
the eye was located about 150 nm southeast of Hong Kong. The typhoon
maintained a more or less steady-state intensity for several days and
then began to slowly weaken. However, the areal extent of gales
increased some during this period. Babs had weakened into a minimal
typhoon by 26/0000 UTC but re-intensified some during the day as a
banding-type eye reappeared briefly.
By late on the 26th the storm was weakening once more and was
downgraded to a tropical storm at 0000 UTC on 27 Oct. At 27/0600 UTC
synoptic reports from Chinmen (WMO 46736) and Xiamen (WMO 59134)
indicated that the center of Babs was just southeast of those stations
on the coast of China. Babs was downgraded to a tropical depression
at 1200 UTC and was dissipating by 1800 UTC along the Chinese coast
west of northern Taiwan. This rapid demise of Babs was primarily
caused by the storm moving into a region of very strong vertical
shear.
Typhoon Babs/Loleng was quite destructive to the Philippines. The
latest fatality count located by the author was 221, with 199 of these
occurring in the Bicol region in the extreme southern tip of Luzon,
and 22 elsewhere. Catanduanes Island was the first Philippine Island
to be affected by Loleng, and was one of the hardest hit. Seventy-one
deaths were reported there with 50 in the town of San Miguel. Most of
these deaths were caused by landslides. In nearby Camarines Sur
province, 41 fatalities were reported from drowning, landslides, and
electrocution. Some of the deaths reported across the Philippines
resulted from poisonous snakebites and falling debris. Many of the
deaths were caused by a delay in evacuating families who tried to move
to safer ground during the height of the typhoon.
Torrential rains unleased 1.5 m high avalanches of volcanic material
on Mount Pinatubo but the swollen rivers were able to channel off the
flows, thus averting the threat of mudslides. Hundreds of thousands
of people were left homeless by the typhoon. The total combined
losses from Typhoons Iliang and Loleng were estimated at 6.57 billion
in Philippine dollars. Four billion of these were in agricultural
losses. The hard-hit Bicol region is one of the country's key coconut
growing regions, and widespread severe damage to coconut trees
occurred. Also, major rice growing areas of Luzon were affected by
the storm. Economic analysts stated that the combined effects of the
two typhoons was likely to turn a mild economic slowdown into a full-
scale recession.
Three people were reported killed in Taiwan, where 508 mm of rain
was reported in 24 hrs during the final days of Babs' life.
The following websites contain more detailed information on the
effects of Typhoon Loleng in the Philippines:
(1) http://www.inquirer.net/issues/nov98/nov03/news/news_14.htm>
(2) http://www.inquirer.net/issues/oct98/oct25/index.htm>
(3) http://www.inquirer.net/issues/oct98/oct26/index.htm>
(4) http://www.disasterrelief.org/Disasters/981023Babs2/>
***********************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for October: 3 tropical depressions
1 tropical cyclone of gale intensity
NOTE: The tracking and intensity information for North Indian Ocean
Basin tropical cyclones is based primarily upon operational warnings
from the Joint Typhoon Warning Center of the U.S. Air Force and Navy
(JTWC) on the island of Guam. For weaker systems not in warning
status by JTWC, information gleaned from the twice-daily issuances
of the Indian Meteorological Department (IMD) was used to complete
the tracks. These bulletins usually give analyzed center positions
at either 0300 or 0600 UTC and 1200 or 1500 UTC.
The MSW are based on a 1-min 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 region,
both 10-min and 3-min average winds are employed, but IMD makes no
attempt to modify the Dvorak scale for estimating tropical cyclone
intensity; hence, a 1-min avg MSW is implied. In the North Indian
basin JTWC usually does not initiate warnings until a system is
well-organized and likely to attain tropical storm status within
48 hours.
Tropical Depression
8 - 9 October
-------------------
A low-pressure area in the Arabian Sea was carried as a depression
by IMD. The system was located about 450 nm southwest of Bombay at
0300 UTC on 8 Oct. The depression moved west-northwestward and
weakened on 9 Oct. At 0600 UTC the weakening center was located about
575 nm west-southwest of Bombay and was not mentioned in any further
bulletins. The IMD bulletins classified this system as a deep
depression which implies winds of 30 kts.
Tropical Cyclone (TC-05A)
10 - 17 October
--------------------------
A weak LOW formed over the southeastern Arabian Sea just west of
the Laccadive Islands. Over the next several days this system was
tracked by IMD northwestward to a position a few hundred miles off
the coast of Oman by 0600 UTC on the 15th. Tropical Weather Outlooks
issued by JTWC had given the disturbance poor development potential
on previous days, but a Formation Alert was issued at 0900 UTC on
15 Oct based on a scatterometer pass which indicated winds of 20-25
kts associated with a well-defined low-level circulation. Some deep
convection was present to the west of the center.
The system was upgraded to a minimal tropical cyclone at 16/0000
UTC based on scatterometer data showing 35-kt winds south of the
center. The center was located about 425 nm west-southwest of Bombay.
The cyclone moved initially east-northeastward, then turned to more of
a north-northeasterly course. After its initial strengthening the
cyclone did not intensify further and consisted mainly of a low-level
circulation with very little deep convection. Strong vertical shear
was present over the weak cyclone throughout most of its short life.
The center made landfall on the Kathiawar Peninsula just south of the
Gulf of Cutch in northwestern India. This was the region which
experienced disastrous loss of life when it was struck by a tropical
cyclone of hurricane force (TC-03A) in early June. Fortunately
TC-05A weakened and the MSW was estimated at only 30 kts at landfall.
Tropical Depression
13 - 14 October
-------------------
IMD tracked a short-lived system in the Bay of Bengal which was
carried as a fairly weak depression. The system was first mentioned
at 1200 UTC on 13 Oct when the center was estimated to be located
about 150 nm south-southwest of Vishakhapatnam. The depression
subsequently drifted westward and onto the Indian coast near Narsapur
in Andhra Pradesh state by 14/0300 UTC.
Tropical Depression
28 - 29 October
-------------------
The fourth depression of October to be tracked by IMD formed in the
southeastern Bay of Bengal on 28 Oct. At 0600 UTC the center was
estimated to be located about 300 nm south-southeast of Vishakhapatnam.
This system was estimated to have generated 30-kt winds as it drifted
generally to the west-northwest. On 29 Oct the system weakened and
appears to have dissipated off the coast of southern Andhra Pradesh.
***********************************************************************
SOUTH INDIAN OCEAN (SIO) - South Indian Ocean West of Longitude 90E
Activity for October: No tropical cyclones
***********************************************************************
AUSTRALIAN REGION (AUG) - From Longitude 90E Eastward to Longitude 160E
Activity for October: 1 tropical cyclone of storm intensity
1998-1999 TROPICAL CYCLONE NAMES FOR THE AUSTRALIAN REGION
The three Australian TCWC's (Perth, Darwin, and Brisbane) each have
their own sets of names for cyclones developing within their respective
areas of warning responsibility. Perth assigns names for cyclones
forming in the southeastern Indian Ocean from 129E to 90E; Darwin
covers the waters off the Northern Territory and in the western Gulf
of Carpentaria lying between 129E and 138E; and Brisbane's area
includes the eastern Gulf east of 138E, and the Coral Sea and South
Pacific eastward to 160E. Additionally, Papua New Guinea's TCWC at
Port Moresby maintains a list of native names for the very rare
cyclones which form in the waters just off the PNG coast, the Bismarck
Archipelago, and the western Solomon Islands west of 160E.
Names for the upcoming season are (** indicates name has already
been assigned as of 22 November):
Perth - Zelia **, Alison **, Billy, Cathy, Damien, Elle,
Frederic, Gwenda, Hamish, Ilsa, John, Kirrily, Leon,
Marcia, Norman
Darwin - Thelma, Vance, Winsome, Alistair, Bonnie, Craig,
Debbie, Evan
Brisbane - Olinda, Pete, Rona, Sandy, Tessi, Vaughan, Wylva,
Abigail, Bernie, Claudia, Des, Erica, Fritz, Grace,
Harvey
Port Moresby - Epi, Guba, Ila, Kama, Matere, Rowe, Tako, Upia
The primary source of information for Australian Region tropical
cyclones are the warnings and bulletins issued by the three TCWC's
at Perth, Darwin, and Brisbane. Information gleaned from JTWC's
warnings is used as a supplement for times when it was impossible to
obtain Australian bulletins and for comparison purposes. Additionally,
some information came from the Monthly Report of the RSMC at Darwin,
Northern Territory. References to sustained winds should be
understood as being based on a 10-min averaging period unless
otherwise noted.
Tropical Cyclone Zelia (TC-03S)
7 - 10 October
---------------------------------
Zelia was an unusually early-season tropical cyclone which developed
well over 1000 nm off the coast of Western Australia from a convective
cluster in the monsoon trough southwest of Sumatra. At 0400 UTC on
7 Oct the Perth TCWC issued a bulletin on a developing tropical LOW
centered about 350 nm west-northwest of the Cocos Islands. JTWC was
carrying this as a 35-kt (1-min MSW) cyclone at this time. The basis
for JTWC's intensity was a ship report of 25-kt winds (10-min avg)
about 3 degrees from the center. The LOW formed in an area of
moderate windshear and initially intensified quite slowly. The initial
motion was east-southeastward, then gradually turning more to the
southeast.
On 8 Oct the system moved between two high-pressure ridges and the
shear lessened. Perth named the cyclone Zelia at 1000 UTC with the
MSW estimated at 40 kts. Zelia at this time was located about 230 nm
southwest of the Cocos Islands. Peak estimated intensity of 55 kts
occurred at 1600 UTC on the 8th. Shortly after reaching peak intensity
Zelia began to encounter extensive vertical windshear. Both Perth and
JTWC tracked the cyclone southward to 17.5 S based on nighttime
infrared satellite imagery; however, first visible imagery on the 9th
showed Zelia to be severely sheared with the low-level center located
approximately 230 nm northwest of the primary convection. Both TCWC's
re-located the low-level center back to near 15.0 S. Perth issued
the final warning at 09/0400 UTC but JTWC continued to track the system
as a weakening minimal cyclone for another day. Following this
re-location Zelia moved erratically in the area generally about 200 nm
southwest of Cocos; then on 10 Oct began to move west-northwestward
in southeasterly inflow following the passage of a cold front to the
south. JTWC wrote its final warning on the rapidly weakening system
at 1200 UTC on 10 Oct.
It is interesting to note that JTWC's highest 1-min MSW was only
45 kts while Perth's peak 10-min MSW was reported as 55 kts. This
serves as a very good illustration of the (sometimes considerable)
uncertainties inherent in trying to estimate tropical cyclone intensity
from satellite imagery. Furthermore, the drastic re-location of
Zelia's center on 9 Oct provides a good example of the difficulties
often encountered in following systems without a well-defined eye
at night with only infrared imagery available.
***********************************************************************
SOUTHWEST PACIFIC (SWP) - South Pacific Ocean East of Longitude 160E
Activity for October: No tropical cyclones
1998-1999 TROPICAL CYCLONE NAMES FOR THE SOUTHWEST PACIFIC
The Fiji Meteorological Service (TCWC at Nadi) bestows names upon
tropical cyclones developing in the South Pacific between 160E and
120W, which effectively covers the cyclogenetical area. Names for
the upcoming season include:
Cora, Dani, Ella, Frank, Gita, Hali, Iris, Jo, Kim, Leo, Mona,
Neil, Oma, Paula, Rita, Sam, Trina, Uka, Vicky, Walter
***********************************************************************
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 included in the July summary.
I will include this glossary from time to time, primarily in "lean"
months without a lot of tropical cyclone activity to cover. But if
anyone missed receiving it and wishes to obtain a copy, send me an
e-mail privately and I'll forward them a copy.
***********************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
in the following manner:
(a) FTP to: hrd-type42.nhc.noaa.gov [140.90.176.206]
(b) Login as: anonymous
(c) For a password use your e-mail address
(d) Go to "data" subdirectory (Type: cd data)
(e) Set file type to ASCII (Type: ascii)
(f) Transfer file (Type: get remote_file_name local_file_name )
(The files will be named with an obvious nomenclature--using
October as an example: oct98.tracks)
(g) To exit FTP, type: quit
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. If anyone wishes to retrieve any of the previous summaries,
they may be downloaded from the aforementioned FTP site at HRD. The
summary files are catalogued with the nomenclature: oct98.sum, for
example.
Back issues can also be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, and Tom Berg):
http://australiansevereweather.com/cyclones/>
http://www.geocities.com/capecanaveral/6825> (since January only)
http://www.hcane.com/tropcl.html>
The preliminary storm reports for all the 1997 Atlantic and Eastern
North Pacific tropical cyclones are available on the Tropical
Prediction Center's website: http://www.nhc.noaa.gov> . These
reports include the analyzed best-track for each cyclone. The staff
of JTWC is also working on an on-line version of their Annual Tropical
Cyclone Report for 1997. It is still under construction, but the
best-track files are already available for 1997 Northwestern Pacific
and North Indian Ocean cyclones. The URL is:
http://www.npmocw.navy.mil/npmocw/prods/jtwc.html>
Prepared by: Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays)
***********************************************************************
***********************************************************************
|
Document: summ9810.htm
Updated: 18th March 2008 |
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