MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
JANUARY, 2003
Part 2
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
NOTE: The January summary is being issued in two parts. The first
installment covered the Northwest Pacific and Southwest Indian Ocean
basins and contained the Feature of the Month. This second part
covers the Australian Region and the South Pacific basin.
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JANUARY HIGHLIGHTS
--> Tropical storm strikes Madagascar
--> South Pacific continues active with two intense cyclones
--> Fiji experiences devastating cyclone strike
--> Monsoon depression surprises Australian forecasters
--> First Northwest Pacific tropical storm of year forms
*************************************************************************
***** Feature of the Month for January *****
NOTE!!! The Feature of the Month appeared in Part 1 of the January
summary.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for January: No tropical cyclones
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NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for January: No tropical cyclones
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NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for January: 1 tropical storm
NOTE!!! The Northwest Pacific basin was covered in Part 1 of the
January summary.
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NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for January: No tropical cyclones
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SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for January: 1 tropical disturbance
2 severe tropical storms
NOTE!!! The Southwest Indian Ocean basin was covered in Part 1 of the
January summary.
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for January: 1 tropical LOW **
** - system formed east of 135E and moved westward into Perth's AOR
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Northwest Australia/Southeast Indian Ocean tropical cyclones are
the warnings and advices issued by the Tropical Cyclone Warning
Centres at Perth, Western Australia, and Darwin, Northern Territory.
References to sustained winds imply a 10-minute averaging period
unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Australian centres' coor-
dinates by usually 40-50 nm or more. The JTWC warnings are also the
source of the 1-minute average maximum sustained wind values included
in the tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Northwest Australia/Southeast Indian Ocean
Tropical Activity for January
------------------------------------------
The only tropical system for which warnings were issued between
longitudes 135E and 90E during January was a tropical LOW in the Timor
Sea on the 23rd and 24th. This system was a reincarnation of a long-
lived, interesting system which had formed in the Arafura Sea very early
in the month. The system was not classified operationally as a tropical
cyclone, but a post-event analysis concluded that early in its history
the LOW had reached tropical cyclone intensity as it moved inland into
the Northern Territory across Elcho Island. For the most part the system
exhibited monsoon depression characteristics and spent the middle two
weeks of January meandering around the Northern Territory. A post-event
study by the Perth TCWC has concluded that the LOW became a tropical
cyclone for a second time as it made landfall in Western Australia
between Port Hedland and Pardoo on the 24th. A report on this system is
included in the next section of this summary covering the Northeast
Australia/Coral Sea region.
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NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for January: 1 tropical LOW (monsoon depression) **
** - system was ajudged in post-analysis to have reached tropical cyclone
intensity at one point
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Northeast Australia/Coral Sea tropical cyclones are the warnings
and advices issued by the Tropical Cyclone Warning Centres at
Brisbane, Queensland, and Darwin, Northern Territory, and on very
infrequent occasions, by the centre at Port Moresby, Papua New
Guinea. References to sustained winds imply a 10-minute averaging
period unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Australian centres' coor-
dinates by usually 40-50 nm or more. The JTWC warnings are also the
source of the 1-minute average maximum sustained wind values included
in the tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Northeast Australia/Coral Sea
Tropical Activity for January
-----------------------------
No tropical cyclones were declared operationally east of longitude
135E during January. The main highlight of the month was a very long-
lived monsoon depression which formed in the Arafura Sea very early in
the month and lasted for almost three weeks. A damage survey and
examination of AWS data from Elcho Island indicated that the system had
developed into a small tropical cyclone of storm intensity on the 4th
and 5th as it moved across the island. The system later parked itself
over or near the western Gulf of Carpentaria for several days where it
spawned very heavy rainfall which led to major flooding in some areas.
After spending several days moving slowly westward across Arnhem Land,
the LOW eventually emerged into the Timor Sea and underwent some
strengthening once more, reaching tropical cyclone intensity a second
time as it came ashore in Western Australia. A report on this system
follows.
Long-lived Monsoon Depression
and
Elcho Island Tropical Cyclone
-----------------------------
A. System History
-----------------
A long-lived monsoon LOW formed in the Arafura Sea on 4 January.
The system moved southward and inland along the Top End of the Northern
Territory on the 5th. Some non-tropical cyclone-style gale warnings
were issued by Darwin, but the system was not considered a tropical
cyclone by Darwin nor by JTWC. The LOW hung around for several days
and by 10 January was near the coastline in the southwestern Gulf of
Carpentaria region. Darwin issued tropical cyclone advices on the 11th
and 12th in the anticipation that the LOW might develop into a tropical
cyclone in the Gulf. By around 1300 UTC on the 11th the center was out
over the Gulf south-southeast of Groote Eylandt, but further development
did not take place and the LOW subsequently began moving westward. By
early on the 14th the system was well inland over the Northern Territory.
The weak system spent roughly the next week moving very slowly
westward across northern Australia, being more of a diffuse trough of
low pressure than a closed LOW. By the 21st a tropical LOW had formed
in the Timor Sea north of the Western Australian coast. Perth began
issuing gale warnings for this LOW on 23 January in the anticipation that
it would develop into a tropical cyclone. The LOW drifted westward,
thence recurving southwestward and southward, finally moving inland just
west of Pardoo around 1900 UTC on the 24th. There was initially some
uncertainty if the Timor Sea tropical LOW was a redevelopment of the
earlier Arafura Sea/Gulf of Carpentaria system. Mark Kersemakers of
the Darwin TCWC indicated that they were separate system, and therefore
I treated them as separate systems in the January tracks file. However,
Mark later informed me that after reviewing the data later, the
consensus of opinion was that the two were one and the same system.
Although the surface circulation had been very difficult to keep tabs
on, it appeared that the mid-level circulation was the same.
B. Tropical Cyclone #1
----------------------
During the time the system was initially developing north of the Top
End coastline, forecasters at the Darwin TCWC analyzed it as a very
broad circulation with bands of gales at wide radii from the center (out
to 180 nm to the north and east). The LOW was expected to move over land
early on 5 January, but remained over water longer than expected, coming
inland near Elcho Island around 0900 UTC (1830 local time--Australian
Central Standard Time). Gales began on Elcho Island at 1850 CST and
lasted until 2000 CST. A secondary maximum with near gale-force winds
of 32 kts occurred at 2230 CST. At 1920 CST sustained winds reached
50 kts with peak gusts of 62 kts, accompanied by a MSLP of 991.7 mb. The
minimum MSLP reading of 989.8 mb occurred at 2010 CST.
A damage survey was conducted on Elcho Island several days later.
Extensive tree damage was noted, mainly from southerly or westerly winds.
There was also some damage to buildings and vehicles, largely due to
falling trees. An extensive post-event analysis has concluded that the
system reached tropical cyclone strength around 04/2100 UTC, and with the
benefit of hindsight, a Dvorak CI of around 3.0 to 3.5 can be assigned
at the time of landfall. Images from the Gove radar showed a C-shaped
structure with a radius of around 10 nm which persisted for many hours,
and can be associated with the band of maximum winds. It is estimated
that the radius of gales in the core region was around 15 nm.
Fortunately, there were no injuries. The main human impact on Elcho
Island was panic and confusion with people running or driving around in
dangerous conditions. The inhabitants of the island were not expecting
a tropical cyclone since no warnings had been issued, and apparently
the people there had not heard nor understood the gale warnings that were
in force for Arnhem Land.
The asymmetry of the winds around the system are particularly inter-
esting. Winds were much stronger in southerly (offshore) flow on the
west side of the center--the same side as the C-shaped structure on
radar--than in the northerly flow east of the center. On the eastern
side the wind field consisted of a more broad area of gales which
persisted for another twelve hours while the system rapidly moved
off to the west-southwest--a feature more consistent with the monsoon
LOW structure analyzed in real time. It's possible that the system
was a hybrid, with a small tropical cyclone developing within a broader,
annular system.
C. Best Track
-------------
Following is the post-event analysis best track for the Elcho Island
portion of the system's history. This was sent to me by Peter Otto--a
special thanks to Peter for forwarding it to me. I will include this
track in the March tropical cyclone tracks file as an addendum.
Date Time Lat Lon Cent MSW MSW Remarks
(GMT) Press 1-min 10-min
(mb) (kts) (kts)
-------------------------------------------------------------------------
03 JAN 04 0000 10.0 S 135.5 E 1004 15
03 JAN 04 0300 10.2 S 136.0 E 1002 15
03 JAN 04 0600 10.4 S 136.3 E 1000 20
03 JAN 04 0900 10.7 S 136.4 E 999 20
03 JAN 04 1200 11.2 S 136.3 E 998 25
03 JAN 04 1500 11.3 S 135.9 E 996 30
03 JAN 04 1800 11.4 S 135.7 E 994 30
03 JAN 04 2100 11.4 S 135.6 E 992 35
03 JAN 05 0000 11.4 S 135.4 E 991 35
03 JAN 05 0300 11.5 S 135.5 E 990 40
03 JAN 05 0600 11.6 S 135.8 E 989 45
03 JAN 05 0900 11.9 S 135.8 E 988 50
03 JAN 05 1200 12.1 S 135.5 E 988 50
03 JAN 05 1500 12.3 S 135.0 E 990 40
03 JAN 05 1800 12.4 S 134.9 E 993 35
03 JAN 06 0000 12.6 S 134.7 E 997 30
D. Meteorological Observations
------------------------------
The folks at the Darwin TCWC prepared a summary of observations in
and around the Gulf of Carpentaria during the time the monsoon LOW was
affecting that region. I'm not sure just who sent it to me (I saved
only the attachment and not the e-mail message), but I'd like to thank
whomever it was. The maximum wind gust recorded was 52 kts at Sweers
Island (17.1S, 139.6E) on 16 January. Centre Island (15.7S, 136.8E)
recorded a peak gust of 47 kts on the 14th while the Mornington Island
AWS (16.7S, 139.2E) recorded a peak gust of 37 kts at 0900 UTC on the
16th. (This last observation is thought to be closer to a 10-minute
average value due to the AWS being surrounded by large trees and close
to a building.)
Some of the more significant 24-hour rainfall totals include:
Location Period Ending Amount (mm)
-----------------------------------------------------------------------
Sweers Island 10 Jan/2300 UTC 138
" 11 Jan/2300 UTC 162
Mornington Island 10 Jan/2300 UTC 172
" 11 Jan/2300 UTC 298
" 16 Jan/2300 UTC 210
Centre Island 14 Jan/2300 UTC 159
Boroloola 07 Jan/2300 UTC 164
" 08 Jan/2300 UTC 102
" 09 Jan/2300 UTC 179
" 13 Jan/2300 UTC 103
Groote Eylandt 05 Jan/2300 UTC 140
Gove 14 Jan/2300 UTC 100
Several localities had 24-hour rainfall totals in the 80-100 mm range.
Moderate to major flooding occurred in the Nicholson River catchment.
Rainfall accumulations in or near the catchment over the period
07 Jan/2300 UTC to 22 Jan/2300 UTC include:
Redbank Mine 1103 mm
Woologorang 880 mm
Westmorland 889 mm
E. Possible Tropical Cyclone #2
-------------------------------
As mentioned earlier, the remnants of the monsoon LOW/tropical cyclone
eventually emerged into the Timor Sea off Western Australia and developed
into a tropical depression. The system was forecast to intensify into
a tropical cyclone and precautionary gale warnings were issued by the
Perth TCWC, but the system did not strengthen. Or so was thought.
According to an e-mail from Barry Hanstrum of the Perth TCWC, off the
Western Australian coast the LOW's structure was monsoonal and multi-
centered as it had been in the Arafura Sea. However, during the period
around landfall just to the east of Port Hedland, a region of strong
gales was observed in the offshore flow immediately to the west of and
north of the LOW--very similar to the situation at Elcho Island. The
Perth office will be performing a careful analysis of the system and
there is a possibility it may be later upgraded to tropical cyclone
status a second time.
UPDATE: I have learned from Mark Kersemakers that a post-analysis
study of this system has determined that it did reach tropical cyclone
intensity shortly before moving ashore in Western Australia. If and
when I receive a tabular "best track" for this portion of the system,
I will include it in a future summary.
(Report written by Gary Padgett)
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SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for January: 1 tropical cyclone of gale intensity
2 tropical cyclones of hurricane intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
South Pacific tropical cyclones are the warnings and advisories
issued by the Tropical Cyclone Warning Centres at Nadi, Fiji (for
waters north of latitude 25S), and Wellington, New Zealand (for
waters south of latitude 25S). References to sustained winds imply
a 10-minute averaging period unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Southern Hemisphere
centres' coordinates by usually 40-50 nm or more. The JTWC warnings
are also the source of the 1-minute average maximum sustained wind
values included in the tracks file. Additionally, information
describing details of satellite imagery and atmospheric circulation
features included in the narratives is often gleaned from the JTWC
warnings.
South Pacific Tropical Activity for January
-------------------------------------------
Three tropical cyclones formed in the South Pacific Ocean east of 160E
during January. One of these systems, Cilla, was of minimal tropical
cyclone intensity and of little consequence. The other two, however,
became quite intense and one was very destructive to Fiji. Tropical
Cyclone Ami cut a destructive swath across the Northern and Eastern
Divisions of Fiji, resulting in total losses possibly exceeding
$100 million in Fijian dollars and claiming 14 lives. Later, Tropical
Cyclone Beni became even more intense and caused some damage in the
Solomons and Vanuatu as it passed near those island groups, but
fortunately no loss of life is known to have resulted. Beni weakened to
a tropical depression southwest of New Caledonia, but the remnant LOW
moved westward and briefly regained tropical cyclone status off the
Queensland coast in early February.
The reports on Tropical Cyclones Ami and Beni were written by Simon
Clarke of Cleveland, Queensland, and these were based in part on storm
reports received from Alipate Waqaicelua, Chief Forecaster at the Nadi
TCWC. A special thanks to Simon and Alipate for their assistance.
TROPICAL CYCLONE AMI
(TD-05F / TC-10P)
9 - 15 January
----------------------------------------
A. Storm Origins
----------------
Ami was the third tropical cyclone to form in the RSMC Nadi's area of
responsibility during the 2002-2003 South Pacific Tropical Cyclone
Season.
A tropical depression (TD-05F) was first identified as an embedded
system in an active monsoon trough to the east of Tuvalu, or about
240 nautical miles east of Funafuti at around 09/2100 UTC. The system
steadily moved southwestward to lie close to Niulakita early on the
12th, with development greatly affected by diurnal variations and
relatively strong vertical wind shear.
Overnight on 11 January, the central convection increased and
became much better organised over the LLCC. Under favourable
diffluent air conditions aloft and with low to moderate vertical wind
shear, TD-05F underwent steady development and subsequently was named
Tropical Cyclone Ami around 0000 UTC on 12 January. Ami was located
just east of Niulakita at the time and moving steadily southwestward
with maximum 10-minute mean winds estimated at 40 knots.
B. Track and Intensity History
------------------------------
Initially, Ami moved toward the southwest at approximately 6 knots
and intensified rapidly with banding wrapping into the southern semi-
circle of the low-level circulation. Ami slowly turned toward the
south and reached storm intensity (50 knots) around 12/1200 UTC.
Around 13/0600 UTC, Ami attained hurricane intensity whilst
accelerating toward the south at 12 knots. Ami exhibited good outflow
in all quadrants as a deepening upper-level trough southwest of the
cyclone increased the outflow above the system. A ragged eye had
become visible in satellite imagery, and the storm's centre was then
located (by radar) about 140 nautical miles north-northeast of Labasa
or about 130 nautical miles north-northwest of Udu Point.
The centre of the cyclone made landfall near Dogotuki, Vanua Levu,
slightly after 13/1500 UTC. At this time, Ami had a MSW of 75 knots
(or 90 knots MSW 1-minute average per JTWC) close to the centre and a
central pressure estimated at 960 hPa.
The centre of the cyclone passed over the western tip of Taveuni
after 13/1700 UTC before accelerating through the Lau Group, curving
southeastward as it did so. At 14/0600 UTC Ami reached its peak
intensity of 80 knots (or 110 knots 1-minute average per JTWC) with an
estimated central pressure of 950 hPa. The centre was located about
60 nautical miles south-southwest of Lakeba, or about 100 nautical miles
north-northwest of Ono-i-Lau. (Editor's Note: JTWC based its estimated
peak 1-minute average MSW of 110 kts on CI estimates of 102 and 115 kts,
or T5.5 and T6.0. Fiji's analysis yielded a final T-number of 5.5, but
the CI was held to 5.0--90 kts 1-minute or 80 kts 10-minute average. So
whether or not Ami became an intense tropical cyclone (100 kts 1-minute/
90 kts 10-minute) isn't quite such a clear-cut issue as with the other
intense South Pacific cyclones this season.)
Ami maintained its southeasterly track and accelerated further to
between 30 and 35 knots as it moved out of RSMC Nadi's area of warning
responsibility. By this time Ami was tracking poleward of the upper-
level ridge axis and encountering increasing vertical wind sheer and
cooler sea surface temperatures. Ami began to interact with a frontal
boundary to its immediate southwest and underwent complete extratropical
transition by 15/1200 UTC whilst inside the RSMC Wellington's area of
responsibility. The remains of Ami were last seen tracking toward the
east about 600 nautical miles south-southeast of Rarotonga.
C. Damage and Casualties
------------------------
Ami was a relatively intense tropical cyclone with maximum (10-
minute average) winds of about 80 knots and momentary gusts of 110
knots at its peak intensity. The cyclone caused destructive to very
destructive storm and hurricane-force winds over Fiji's Northern and
Central Divisions, and damaging gale-force winds over Tonga and
Tuvalu. Damage was extensive and severe, especially to roads,
infrastructure, buildings, houses, crops (particularly hard-hit being
the sugar industry) and vegetation over Macuata, Cakaudrove and Lau
Provinces in Fiji's Northern and Eastern Divisions.
Fiji's Disaster Management Centre declared the northern island of
Vanua Levu a natural disaster zone. Communication to and within the
Northern and Eastern Divisions was severed for several days after the
passage of Ami. Severe flooding in Labasa from its river took a heavy
toll on the township's residents and caused serious health and
environmental risks. Water supplies in the Northern Division were
severely disrupted, leaving residents without clean drinking water
for several days and forcing the Government to cart fresh water from
mainland Viti Levu to the affected areas. Torrential rains also caused
landslides. High waves and a heavy surge generated by Ami caused
coastal and inland inundation in many areas along its path, some
quite severe.
The following figures from the Government of Fiji show the extent of
the damage:
Housing:
-> In Lau and Lomaiviti, but mostly in Lau - 237 houses were
partially damaged and 158 completely destroyed; the total
estimated cost was $2.2 million.
-> In Macuata, Cakaudrove and Bua, and mostly in Macuata and
Cakaudrove - 5300 houses were partially damaged and 2287
completely destroyed; total estimated cost was $11.6 million.
Health Facilities:
-> The Visoqo Nursing Station was completely destroyed, with
structural damage sustained to the Labasa and Savusavu
hospitals and various health centres and nursing stations.
Infrastructure:
-> Damage to roads, bridges and jetties estimated at $2.7 million
-> Damage to water and sewerage systems of $79,300
-> Damage to rural water supply systems of $1 million
-> Damage to Government buildings of $101,000
-> Damage to electricity infrastructure of $3.4 million
Agriculture:
-> Damage assessment by the Ministry estimates the cost of
rehabilitation at $1 million for the non-sugar sector.
-> For the cane and sugar sector, the 2003 cane is estimated to
suffer a reduction of 15% on the 2003 forecast of 800,000
tonnes. This means an estimated loss of $8 million with
$6 million required for the heavy damage sustained to the Labasa
Mill.
-> Widespread damage sustained to coconut plantations with an
estimated three to five year period required for the trees to be
productive again.
The extent of damage requiring immediate Government attention has
been valued at $F60 million. However, the socio-economic loss is
likely to exceed $F100 million.
Fiji's National Emergency Operational Centre confirmed the total
number of fatalities to be fourteen.
Preliminary information provided by the Tonga Meteorological Service
reveals that damage suffered in Tonga was mainly to fruit bearing trees.
The inter-island ferry MV Olovaha was left stranded on a reef in
Tongatapu. Nuku'alofa reported a maximum sustained wind of 40 knots
with gusts to 60 knots.
Some pictures of Tropical Cyclone Ami's brush with Tonga may be
found on Geoff Mackley's website:
<http://www.rambocam.com/ami.html>
Additional articles on the effects of Tropical Cyclone Ami in Fiji
can be found at the following URL:
<http://www.reliefweb.int/w/rwb.nsf/vLND>
(Report written by Simon Clarke with contributions by Alipate
Waqaicelua, Chief Forecaster at the Nadi TCWC)
TROPICAL CYCLONE BENI
(TD-06F / TC-12P)
19 January - 5 February 2003
------------------------------------------------
A. Storm Origins
----------------
Beni was the fourth tropical cyclone of the 2002-2003 South Pacific
Tropical Cyclone Season, and the first of the season to cross over
into the Queensland Tropical Cyclone Warning Centre's area of warning
responsibility.
Beni was first identified at 19/1800 UTC as a broad circulation
embedded in the monsoon trough to the northeast of the Santa Cruz
Islands and moving towards the west-southwest at about 5 knots. At the
time, the disturbance was located in a favourable outflow environment
with minimal shear and a SST of approximately 30 C. The system was
upgraded to Tropical Depression 06F after 24 hours while steadily
travelling towards the west, being located at 20/2100 UTC about 200 nm
northeast of Rennell Island in the Solomons. However, from 22 January
through 23 January, further development was suppressed by strengthening
vertical wind shear which exposed the LLCC to the east of the deepest
convection.
After 23/2100 UTC, TD-06F returned to a favourable environment for
development consisting of high SSTs, decreasing vertical wind shear,
and a position beneath an upper-level ridge axis with fair and improving
outflow in all quadrants. Accordingly, convection erupted over the LLCC
during the night whilst cooling significantly.
The first international marine warning on TD-06F was then issued at
24/2155 UTC, mentioning winds reaching gale force within 60 nautical
miles of the centre in the next 12 to 24 hours. TD-06F was
subsequently upgraded and named Tropical Cyclone Beni at 25/0000 UTC.
B. Track and Intensity History
------------------------------
At the time of naming, the slow-moving Beni was located about
90 nautical miles southeast of Rennell Island in the Solomon Island
chain. For the ensuing 24 to 48 hours, Beni underwent a slow clockwise
loop while remaining to the southeast of Rennell Island. This motion
was partly a consequence of a strong surface ridge to the south of
the LLCC. Again, under fluctuating environmental conditions primarily
as a consequence of its position north of the strongly diffluent flow
on the northern side of the upper-level ridge axis, Beni exhibited a
partially-exposed LLCC and broken feeder bands with the best areal
coverage of convection on its western flank.
By 26/0600 UTC, Beni began to adopt a more definite but slow path
towards the south-southwest and was set to embark into a region of
increasingly favourable conditions for development. Steady
intensification was the result.
By 28/0600 UTC Beni was beginning to recurve towards the southeast
under the increasing influence of a low to mid-level equatorial ridge
to the east-northeast of the system and as the ridge anchored to the
southwest weakened due to a passing mid-latitude trough. At this time
Beni attained hurricane intensity (> 63 knots), and by 28/1800 UTC,
the cyclone was estimated to have 10-minute average winds of 90 knots
close to the centre. A ragged eye appeared on infrared satellite
imagery and became increasingly well-defined while shrinking in size.
Beni slowly accelerated towards the southeast while intensifying.
Beni reached its peak intensity around 29/0600 UTC with the MSW
estimated at 110 knots (or approximately 125 knots 1-minute average)
close to the centre. At its peak Beni possessed an estimated central
pressure of 920 hPa and was located at 17.0S, 163.7E, or approximately
120 nautical miles to the north of the northwestern tip of New
Caledonia. This position was also roughly 275 nautical miles west of
Port Vila, Vanuatu. Gales extended outward from the centre 120 nm in
all quadrants, and the radius of 50-kt winds was estimated to be on
the order of 50 nm.
Warm air intrusion, increasing wind shear and anomalously cool SSTs
caused Beni to weaken from 29/1200 UTC onward. Within 24 hours after
its peak, Beni, with winds of 85 knots was causing gales and storm-force
winds in parts of central Vanuatu as it passed between that nation and
New Caledonia.
By 30/2000 UTC, a strengthening ridge to the south of Beni had turned
the system to a southerly and eventually southwesterly path around the
southeastern tip of New Caledonia. By this time increasing vertical
wind shear of 30 to 40 knots had blown away Beni's CDO, exposing the
LLCC. At 30/1800 UTC, Beni was downgraded to a 55-knot storm, and
24 hours later Beni was downgraded to a tropical depression while
located roughly 240 nautical miles west-southwest of the southern tip
of New Caledonia, moving towards the west.
The remains of Beni progressed at approximately 10 to 15 knots
firstly westward, then in a west-northwesterly, and finally a north-
westerly path across the southern Coral Sea. Periodic peripheral
gales persisted between the remnant depression and the low-level ridge
to the south. By 2 February 2003, these peripheral gales had begun
to affect the southeastern Queensland Coast between Sandy Cape and
Coolangatta, and gale warnings were issued by the Bureau of Meteorology,
Queensland.
With increasing sea surface temperatures, Beni managed to regain
deep convection to the southeast of the LLCC and the storm reformed
into a tropical cyclone at 0100 UTC on 4 February 2003 approximately
135 nautical miles east of Mackay at 20.9S, 151.6E. Beni was moving
towards the west at 8 knots at the time with the central pressure
estimated at 995 hPa.
Re-classification as a cyclone was to be brief, however, and Beni was
downgraded to a tropical depression within 12 hours. By the early hours
of 5 February 2003 the depression had drifted ashore near Mackay.
C. Meteorological Observations and Analysis
-------------------------------------------
In post-analysis, Jeff Callaghan of the Queensland Bureau of
Meteorology provided this insight into ex-Tropical Cyclone Beni
following its initial demise south of New Caledonia:
"From 1200 UTC, 29 January 2003 to 31 January 2003, a 500 hPa to
200 hPa LOW developed just to the west of New Caledonia and Beni was
moving beneath 40-knot vertical wind shear (CIMSS data) to the east
of this system at 1200 UTC, 30 January 2003. Beni was consequently
weakening rapidly. The LOW was part of an anticyclonic involution,
and ridging developed south of Beni, steering it westward. The ridging
developed first at low levels while ridging was delayed at 500 hPa
south of Beni as a weakening trough system passed to the south at
1200 UTC, 1 February 2003. This had the effect of displacing the
500 hPa centre of Beni to the southeast of the low-level circulation.
"By 1200 UTC, 2 February 2003, a new anticyclonic involution had
developed over eastern Australia, culminating in a new 500 hPa LOW
southwest of Beni.
"This southwest slope of the circulation resulted in a large area of
warm air advection on the eastern flank of the system. We diagnosed
the warm air advection from the EC 850 hPa, 700 hPa and 500 hPa winds
which of course were backing with height in the warm air advection
region. The convective blow up around 1200 UTC, 3 February 2003
happened when the warm air advection area reached the strong low-level
circulation of Beni. There were 40 to 50-knot northwest winds at
200 hPa over the top of Beni, which kept the convection away from the
centre.
"Gannet Cay AWS (WMO 94379) was in the convective region and recorded
gales from 1300 UTC, 3 February 2003 to 0600 UTC, 4 February 2003 with
a maximum 10-minute mean wind of 41 knots.
"By 1200 UTC, 4 February 2003 there were 70-knot northwest winds at
200 hPa over the system and the low-level centre got further displaced
from the warm air advection and gales. A QuikScat image shows a low-level
centre at 0711 UTC, 4 February 2003 near 19S, 151E, while a band of gales
to 50 knots were located between 21S and 23S to the south and southeast
of the centre. (This gale area was also in the area of strongest warm
air advection based on the 1200 UTC, 4 February 2003 EC winds).
"The isolated low-level circulation then weakened; however, the warm
air advection region came on to the coast and produced very heavy rain."
D. Damage and Casualties
------------------------
Whilst Beni was stationary over the Rennell and Bellona group, the
estimated 2,000 inhabitants were taking shelter in caves on the island
in a similar fashion to the residents of the island of Tikopia
(approximately 600 km to the east), which was severely battered by
Tropical Cyclone Zoe late in December. Winds gusted to between 50 and
60 knots at the town of Bellona as the cyclone passed by, along with a
48-hour period of heavy rains. Contact with the islands was lost during
the storm. Beni was rather destructive to vegetation on the islands,
knocking over extensive food-bearing plants including pawpaw (papaya),
banana and coconut trees. Salt-water inundation damaged some garden
plots, and about 85 buildings constructed of semi-permanent materials
were damaged.
Preliminary reports from the Vanuatu Meteorological Service mentioned
strong winds to marginal gales over central Vanuatu. Over the southern
parts, gale-force winds were experienced with gusts to 50 knots.
Heavy swells and waves were reported from most islands in New
Caledonia and Vanuatu. Inland sea inundation also occurred in some
areas during the passage of Beni between the two countries.
In Australia, some of the best rains seen in many years affected
regions primarily in the coastal zone and hinterland of south-central
Queensland south from around Mackay in association with ex-Tropical
Cyclone Beni. Some areas in and around Gladstone received in excess
of 500 mm of rain during the event. However, much of this rain to the
south of Beni was induced in conjunction with an upper-level LOW over
southeastern Queensland at the time.
There are no known official casualties as a direct result of Beni.
Some pictures of Tropical Cyclone Beni's approach to New Caledonia
may be found on Geoff Mackley's website:
<http://www.rambocam.com/beni.html>
Additional articles on the effects of Beni in the Solomons can be
found at the following URL:
<http://www.reliefweb.int/w/rwb.nsf/vLND>
(Report written by Simon Clarke with contributions by Alipate
Waqaicelua, Chief Forecaster of the Nadi TCWC, and Jeff Callaghan
of the Brisbane TCWC)
TROPICAL CYCLONE CILLA
(TD-07F / TC-13P)
25 - 30 January
------------------------------------------
A. Storm Origins
----------------
An area of convection appeared early on 25 January approximately
325 nm west-northwest of Fiji, and by 1900 UTC was located about 240 nm
west-northwest of Suva. Animated enhanced infrared imagery revealed
increasing deep convection near a LLCC while a 200-mb analysis indicated
favorable outflow aloft associated with the western quadrant of an upper-
level ridge. The system was embedded in the monsoon trough and was fore-
cast to drift southeastward along the trough axis. The Nadi TCWC gave
the disturbance a moderate to high chance of developing into a tropical
cyclone during the next 24-36 hours. Nadi classified the system as
Tropical Depression 07F at 2100 UTC, locating the center about 200 nm
northwest of Fiji with 30-kt maximum winds.
The depression was embedded in an active monsoon trough linking up
with Tropical Cyclone Beni to the northwest. Early on the 26th the LLCC
was difficult to locate in satellite imagery. Radar from Nadi showed
some circulation, but the center was difficult to pinpoint since the
system was on the edge of the radar's range. There was a large area of
convection with the deeper convection located mostly to the southeast
and north of the depression's center. CIMSS data showed low shear over
the LLCC. At 26/1300 UTC JTWC issued a TCFA for the system with deep
convection cycling over a partially-exposed center. Around 1800 UTC
radar animation showed several small eddies with the main LLCC located
about 150 nm east-northeast of Fiji. Most of the deepest convection was
confined to the northeastern quadrant of the system at this time.
B. Track and Intensity History
------------------------------
By 27/0000 UTC the LLCC had moved beneath a small convective cluster
and Nadi upgraded the depression to Tropical Cyclone Cilla. The newly-
christened cyclone was located about 275 nm east of Fiji and moving
east-southeastward. The MSW was estimated at 35 kts. Convection
gradually became better established as the day progressed. CIMSS data
revealed 10-20 kts of shear to the south of Cilla, but the shear was
forecast to decrease with time. JTWC wrote their final warning on
Cilla at 2100 UTC, stating that SSM/I data indicated the mid and upper-
level circulations had begun to decouple from the LLCC and that water
vapor imagery indicated the system was rapidly becoming extratropical.
Nadi's warning at 28/0000 UTC, however, indicated that convective
organization had continued to improve. Cilla's intensity was bumped up
to the peak of 40 kts at 0600 UTC with the center located approximately
440 nm south-southeast of Pago Pago, still moving east-southeastward in
excess of 20 kts. The 1200 UTC advisory from Fiji indicated that the
storm had begun to display some baroclinic characteristics; thus, Cilla
may have become somewhat hybrid in nature by this juncture. By 1800
UTC the LLCC had become partially-exposed but was still under deep
convection which appeared to be struggling against shearing conditions.
The cyclone's forward motion had slowed considerably to 10 kts by this
time.
By 0000 UTC on 29 January the LLCC had once more slipped under the
deep convection, and recent satellite images indicated a banding pattern.
CIMSS data showed the system to be located in a region of light vertical
shear, and Fiji's Dvorak analysis yielded a final T-number of 3.0. The
0600 UTC advisory, however, noted that deep convection had weakened once
more, and the latest CIMSS analysis showed that Cilla was located in
30 kts of shear. (JTWC issued a STWO which assigned a fair potential
for redevelopment to Cilla's "remnants".) The storm began to weaken
quickly thereafter and was downgraded to a tropical depression by Nadi
at 29/1200 UTC when located about 360 nm west of Rarotonga. Winds near
the center were analyzed to be less than gale force, but gales to 35 kts
were occurring within 100 nm of the center in the southern semicircle.
The deep convection was sheared well to the southeast of the LLCC. By
1100 UTC on the 30th the depression had become extratropical about
375 nm southwest of Rarotonga.
C. Damage and Casualties
------------------------
No damage or casualties are known to have resulted from Tropical
Cyclone Cilla.
(Report written by Gary Padgett)
*************************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the July, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
*************************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
from the archive sites listed below. (Note: I do have a limited e-mail
distribution list for the track files. If anyone wishes to receive
these via e-mail, please send me a message.)
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. Back issues can be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Michael Pitt, and
Chris Landsea):
<http://australiasevereweather.com/cyclones/>
<http://www.typhoon2000.ph> OR <http://64.235.42.210>
<http://mpittweather.com>
<ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
Another website where much information about tropical cyclones may
be found is the website for the UK Meteorological Office. Their site
contains a lot of statistical information about tropical cyclones
globally on a monthly basis. The URL is:
<http://www.met-office.gov.uk/sec2/sec2cyclone/sec2cyclone.html>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the complete Annual Tropical
Cyclone Report (ATCR) for 2001 (2000-2001 season for the Southern
Hemisphere). ATCRs for earlier years are available also. Recently
added was the report for the Southern Hemisphere 2001-2002 season.
The URL is: <http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2001 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 2001
Atlantic and Eastern North Pacific cyclones are now available, as
well as track charts and reports on storms from earlier years.
The URL is: <http://www.nhc.noaa.gov>
A special thanks to Michael Bath of 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
John Wallace (Eastern North Pacific, North Indian Ocean, Western
Gulf of Mexico)
E-mail: dosidicus@aol.com
Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South
China Sea)
E-mail: newchapelobservatory@btinternet.com
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: saclarke@iprimus.com.au
*************************************************************************
*************************************************************************
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