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Monthly Global Tropical Cyclone Summary February 2001
[Summaries and Track Data] [Prepared by Gary Padgett]
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Monthly Global Tropical Cyclone Summary February 2001 [Summaries and Track Data] [Prepared by Gary Padgett] |
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
FEBRUARY, 2001
(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.)
***********************************************************************
FEBRUARY HIGHLIGHTS
--> Several tropical cyclones affect northern Australia
--> South Pacific cyclone season finally begins
***********************************************************************
***** Feature of the Month for February *****
An Eyewitness Account of a Very Intense Cyclone
The following narrative was written by Carl Smith, a cyclone
enthusiast who currently lives on the Gold Coast of Queensland, south
of Brisbane. Carl and his family were vacationing near Port Hedland,
Western Australia, in December, 1975, when the very intense Tropical
Cyclone Joan made landfall on the night of December 7th-8th. This
account is based on Carl's personal recollection of the incredible
experience of riding out this monster storm:
"My interest in tropical cyclones really developed from experiencing
a Category 5 cyclone, Tropical Cyclone Joan, in Port Hedland, Western
Australia, in the mid-1970's. I will never forget the thrill of
watching 10 metre (30 feet) high waves crashing on the beach two days
before the arrival of Joan, the intense build-up as this monster storm
approached, the very rough seas washing about 200 metres (~650 feet)
inland near the beachfront motel I was staying in on the evening before
Joan's arrival. The wind gusts increased to 150+ km/hr (81+ kts) as
Joan drew closer during the late evening--then the electricity supply
went, followed soon after by the local ABC radio station. The rest of
the night was spent straining to listen to the BoM updates from ABC
Perth through all the static on the transistor radio and the intense
wind noise outside, and plotting the positions in an old atlas by
gaslight, then later by torch (flashlight) light.
"During the early hours of the morning, the wind pressure on the
motel room door was such that the door bowed so much the latch popped
out of its hole and the door flew open. Then the window in the
opposite wall bowed, its latch also came out, the window flew open,
and the effects of the 200+ km/hr (108+ kt) wind gusts were roaring
through the unit. It took all five of us to manage to shut the door
during a brief lull in the wind, and we jammed a large wardrobe up
against the door and wedged it against a fixed cupbord to discourage
any repeat performance.
"Then the red bricks from the nearby swimming pool wall started
smashing the tiles on the roof, making a series of horrendous noises.
"A little later on (about 4:00 am) Joan changed course a little, and
the 240+ km/hr (130+ kt) wind gusts started to change direction. By
first light (around 5:00 am) we could see the light of the sky where
the ceiling and roof of the toilet/bathroom should have been, and the
noise, whilst still tremendous, had taken on a different quality. We
removed the barricade from the door, opened it, and were greeted with
the most amazing view of the effects of Joan near its full intensity.
As the winds were now at right angles to the door, we were able to
stand out on the verandah of the line of units in relative calm whilst
watching the spray from the ocean coming in over the roof of units to
our left, making a clear curve down to the inground swimming pool in
the courtyard (which had had a red brick wall around it the night
before). We could also see the bluish chlorinated water being sucked
out of the pool, making a neat curve up and over the units to our
right.
"As we watched, rows of tiles were being stripped from the roof of
the units to our left and being flung at amazing speed into the
courtyard, many smashing on impact, then being picked up again and
smashing into the roof of the units to our right. Each impact on the
roof to our right would smash tiles loose and start a chain reaction,
with the roof tiles peeling off like playing cards and becoming
airborne, heading off towards Port Hedland.
"In the direction of Port Hedland, the air was filled with roofing
iron, parts of walls, and other debris for many hundreds of feet into
the air, looking like sheets of paper being blown about by the wind.
"As the day slowly passed, the wind quickly abated, dropping to
(estimated) 100 km/hr (54 kts) by 9:00 am, so we ventured into the open
to have a look around. The previously full 1.8 metre (6 feet) deep
swimming pool had only about 50 mm (2 inches) of now salty water left
in it, along with a considerable amount of beach sand and multitudes
of rather damaged crabs and other sea life. Most of the roof tiles
were gone from the motel, and every building we could see had sustained
heavy damage.
"The damage bill in the mining port town of 17,000 came to around
$22 million (Australian). Port Hedland was lucky to be spared the full
force of the 270 km/hr (147 kt) wind gusts, although I was somewhat
disappointed, as I had been looking forward to an eye passage.
"Port Hedland suffered substantial damage with virtually all houses
and buildings suffering multiple hole damage consistent with large
quantities of flying debris, and many suffering severe structural
damage such as missing roofs and walls. Many reinforced concrete block
buildings had their walls cracked and distorted into weird curves by
the wind pressure--these are "Besser" concrete block walls anchored
with steel reinforcing rods embedded in the reinforced concrete
foundations and extending up through the cavities in the lower layers
of blocks. More long rods are then inserted, extending to the full
height of the wall, with several rods passing through every block
cavity, and the wall cavities are then filled to the top with
concrete--this was the way the motel I was in was constructed.
"In South Hedland many more houses came through it with rather less
damage, mainly consisting of holes made by flying debris, although some
buildings did lose roofs and walls.
"Prior to Joan's crossing the coast about 50 km southwest of Port
Hedland, it passed within about 25-30 km of Port Hedland, so the very
strong wind region around the eyewall passed quite close to the town.
I do not have the data on how large the eye was.
"One of the more revealing signs of the intensity of the wind was
the manner in which the power poles were twisted like spaghetti. The
poles were apparently constructed with severe cyclones in mind, the
bases being tall tripods constructed with lengths of railway track with
their feet buried deep into concrete footings. Many of these, whilst
still seated firmly in the ground, were twisted down to no more than
2 feet off the ground in exposed areas after Joan, and often adjacent
poles were bent in totally different directions, with many being
twisted into quite bizarre shapes, some with roofing iron wrapped
around them. It was quite an eerie sight and points to extreme wind
speeds with lots of localised turbulence in some areas.
"The sustained howling of winds sounded like 1000 express trains all
going past at once with stronger "gusts" of several minutes duration
sounding like 1000 RAAF jets all taking off simultaneously right next
to us. It had to be experienced to be believed. I don't quite know
how to describe it except by way of these inadequate trains and jets!
I suppose they are the only things I can think of that come anywhere
near the quality and intensity of the sound. To talk to anyone was
impossible except by shouting directly into the ear, and I used an
earpiece and covered my ear to get the BoM updates off the radio.
"The fact that nobody was killed is testament to the quality of
buildings in that region, which are very well constructed. Many houses
owned by the mining companies were actually pre-fab cyclone shelters,
trucked up in pieces from workshops in Perth, bolted together, and
tensioned with many heavy steel cables and turn-buckles located inside
the walls, with each house tightened down with turn-buckles on to a
thick reinforced concrete slab, making a tensioned unit that can with-
stand the wind pressure of a Category 5 cyclone.
"The damage to this style of home was mainly from flying debris
penetrating through the cladding on the steel framed weld-mesh
reinforced walls, and there was substantial debris-related roof damage.
The manner in which these houses are constructed and fastened down with
tensioned steel cables means that most of them stayed intact and the
roofs stayed on in spite of having many holes in them from the severe
peppering with airborne debris.
"Some other styles of homes, such as the luxurious ones owned by
company executives and built along the beach front did not fare so
well--many of these lost their roofs and some lost their walls, too."
Regarding the wind velocities mentioned in the account, Carl writes:
"Most of the wind speeds in my account are what I remember many
years after the fact from the BoM Tropical Cyclone Advices read over
ABC radio and the live-to-air telephone calls with BoM forecasters that
gave that kind of information during Joan. ABC radio does a very good
public service during cyclones, ensuring that as much info as possible
is put out over a number of transmitters in different locations during
severe cyclones. Throughout most of the early morning during Joan I
was actually tuned in to the ABC Perth transmitter which was the only
one I could pick through the intense static after the local ABC station
went off the air--the ionospheric skip was happening in the right
place!"
Carl also sent the following correction:
"The 270 km/hr (147 kt) figure mentioned here is an error--I think
the correct figure is about 242 km/hr (131 kts). I pondered over this
for a long time after I originally wrote it and sent it off, and more
recently I have recalled more of the actual conversation the next
morning with the Port Authority officer who was on duty that night and
staying at the same motel. The 270 km/hr figure was the "red-line"
beyond which the tower had to be evacuated for safety reasons. Of
course it was evacuated shortly after the wind speed became
unavailable. The equipment was on the Port Authority Control Tower
at a non-standard height, so even if records have been kept, they
cannot be accepted as "official" in any case. The wind continued to
increase for about two hours after that, so the maximum gust is
anybody's guess, but it was certainly "gusting" (or more correctly
"blasting") above 250km/hr (136 kts) and probably considerably higher
for several hours, perhaps at times pushing through the 300 km/hr
(163 kt) mark in some places."
Carl indicated that he has experienced encounters with quite a few
Australian tropical cyclones over the years, but none came close to
matching the ferocity of Joan. He did relate the following account
of a close encounter with Tropical Cyclone Joy in 1990:
"On Christmas Eve, 1990, a 25 metre (80 feet) high raintree blown
over by Severe Tropical Cyclone Joy (Category 4) crushed the roof of
our caravan at Ellis Beach, 22 km (14 miles) north of Cairns. We were
at a friend's house at the time--teenagers were present so safety
first--otherwise I would have been at the Surf Club near the caravan
park. Joy was about 100 km (54 nm) off Ellis Beach, the closest place
on the mainland, and stationary for 12 hours overnight, blasting Ellis
with a sustained battering of winds frequently gusting to 150 km/hr
(81 kts) (estimated) before turning away. There was significant damage
in and around Cairns (about 110 km or 60 nm from the cyclone centre for
the full 12 hours), which was a little more sheltered from the
continuous battering by winds frequently gusting to 130 km/hr (70 kts)
(BoM measured). The threat of a 15 metre (50 feet) high storm surge
and winds gusting to 240 km/hr (130 kts) near the centre of this very
large cyclone was considered so severe that the Army had 40,000 body
bags on standby to fly in to Cairns should Joy have come ashore there
at high tide."
***********************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for February: No tropical cyclones
***********************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for February: 1 subtropical (Kona) LOW
Northeast Pacific Tropical Activity for February
------------------------------------------------
No tropical cyclones developed in the Northeast Pacific basin during
the month of February, but there was an example of a Kona storm--a type
of subtropical cyclone which forms occasionally in the Hawaiian region
primarily during the winter. David Roth, a meteorologist at the Hydro-
meteorological Prediction Center and a student of hybrid/subtropical
cyclones, sent me a track for the Kona storm which was included in the
cyclone tracks file for February. The LOW had formed by 4 February
when it was located approximately 750 nm northeast of Honolulu at
1200 UTC. It moved south-southwestward over the next couple of days,
reaching a point about 350 nm north-northeast of Honolulu at 1200 UTC
on the 6th. The system then moved west-northwestward at a slightly
faster pace until it degenerated into an open wave after 1800 UTC on
the 8th about 325 nm northwest of Honolulu. David wrote that "the
system began as an occluded cyclone, eventually shedding its fronts
and gathering convection on its eastern side, like most subtropical
cyclones. The highest wind reports seen from ship observations were
45 kts, with the lowest pressure estimated at 1005 mb from the 5th
into the 7th." The MSW values given in the track were taken from
ship reports and not derived from the Hebert-Poteat classification
scheme for subtropical cyclones. (A special thanks to David for
sending me the information on this cyclone.)
***********************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for February: 1 tropical depression
Northwest Pacific Tropical Activity for February
------------------------------------------------
No tropical storms or typhoons formed in the Northwest Pacific
basin during February, but one tropical depression formed and brought
destructive floods and landslides to the Philippines. Warnings were
initiated by PAGASA on the system at 1800 UTC on 17 February when the
broad, ill-defined center was located about 175 nm northeast of Surigao
on the northeastern tip of Mindanao. PAGASA named the depression
Auring (which is a Filipino nickname for the name Aurora). JTWC began
issuing warnings on the system as TD-01W six hours later. Tropical
Depression Auring moved westward toward the Philippine archipelago
and tracked across the islands from near the Leyte Gulf region west-
northwestward across the central Philippines--including the island of
Panay--into the northern Sulu Sea south of Mindoro. PAGASA issued a
final warning on Auring at 19/1800 UTC while JTWC's last warning was
issued at 0600 UTC on the 20th, placing the weak, dissipating center
about 225 nm south of Manila. The peak MSW (1-min avg) assigned by
JTWC was 25 kts while PAGASA estimated peak 10-min avg winds at 30 kts
on the 17th and 18th.
Even though weak from the standpoint of wind, Auring's rains caused
significant damage and at least 18 fatalities. Most of the deaths
were caused by landslides triggered by the torrential rains, with
six people killed in a slide at Sitio Cag-abaca on Leyte (about 80 km
south of Tacloban), while eight persons perished in a landslide at a
mining pit near Mt. Diwalwal in Monkayo, Compostela Valley. More than
100,000 people were driven from their homes in the Visayas and Mindanao
as a result of the landslides, floods, and large waves caused by the
depression. Floods hit Leyte, Davao Oriental, Davao del Norte,
Compostela Valley, Agusan del Sur and Surigao del Sur, reportedly
submerging the homes of 159,785 persons in these regions. Damage to
crops and property as a result of Tropical Depression Auring has been
estimated at more than 200 million pesos. (A special thanks to Michael
Padua for sending me the PAGASA track for Auring as well as information
on damage and casualties.)
***********************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for February: No tropical cyclones
***********************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for February: 1 tropical depression
Southwest Indian Ocean Tropical Activity for February
-----------------------------------------------------
After a very active January which featured three rather intense
tropical cyclones, February was a very quiet month in the Southwest
Indian Ocean west of longitude 90E. Only one system occasioned the
issuance of bulletins by La Reunion, and that was only a tropical
depression. JTWC issued a Formation Alert at 2130 UTC on 31 January
for a weak circulation located about 450 nm northeast of Rodrigues
Island. La Reunion (MFR) issued the first tropical disturbance
bulletin at 0600 UTC on 1 February, designating the system as tropical
disturbance #7. The disturbance was upgraded to a tropical depression
six hours later when central winds (10-min avg) were estimated to have
reached 30 kts. Throughout its life the depression generally moved
on a southerly course which took it out of the tropics. It passed
about 325 nm east of Rodrigues at 02/0000 UTC and by 1200 UTC on the
3rd was becoming extratropical about 675 nm southeast of the island.
The depression displayed a large circulation and 30-kt winds extended
outward from the center about 250-300 nm in the southeastern quadrant.
JTWC did not issue any warnings on this depression, although at
0000 UTC on 2 February a second Formation Alert was issued which
estimated the MSW to be 25-30 kts. (In the Southern Hemisphere JTWC
usually does not initiate warnings until winds have reached 35 kts.)
(A special thanks to Patrick Hoareau for preparing and sending me the
track of this tropical depression.)
***********************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for February: 1 tropical cyclone of storm intensity
The primary sources of information for Northwest Australia/Southeast
Indian Ocean tropical cyclones are the warnings and bulletins issued by
the TCWC at Perth, Western Australia. 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. References
to sustained winds should be understood as being based on a 10-min
averaging period unless otherwise noted.
Patrick Hoareau of Rennes, France, sent me the track for Tropical
Cyclone Vincent already typed in the correct format. A special thanks
to Patrick for providing this service.
A description of the Australian Cyclone Severity Scale can be found
on the Australian Bureau of Meteorology's official website:
http://www.bom.gov.au/info/cyclone/>
Click on the link 'Cyclone Severity Categories'
or on Chris Landsea's FAQ on HRD's website:
http://www.aoml.noaa.gov/hrd/tcfaq/tcfaqD.html#D2>
or on Michael Bath's Australian Severe Weather site:
http://australiasevereweather.com/cyclones/history.htm>
Northwest Australia/Southeast Indian Ocean
Tropical Activity for February
------------------------------------------
As the month of February opened the remnants of Tropical Cyclone
Terri were dissipating inland over Western Australia. Only one other
tropical cyclone stirred the waters off Western Australia during the
month. Tropical Cyclone Vincent formed on the 12th and headed east-
southeastward toward the coast but apparently dissipated rather quickly
in the monsoon trough just offshore on the 15th.
Tropical Cyclone Vincent (TC-09S)
5 - 15 February
----------------------------------
A. Origins
----------
A weak tropical LOW was first mentioned in a TWO issued by Perth
on 5 February, located about 550 nm east of Christmas Island in an
active monsoon trough. The possibility was mentioned of this tropical
LOW interacting with a slow-moving easterly disturbance then located
east of longitude 120E. By the 7th a well-defined mid-level
circulation was evident and models were suggesting further development.
JTWC upgraded the development potential to fair on the 7th and issued
a Formation Alert at 08/2030 UTC for a LLCC located about 450 nm north
of Learmonth. The center was partially-exposed with convection sheared
to the west; however, deep convection was re-establishing itself over
the LLCC. A 200-mb analysis indicated that the LOW was equatorward of
the upper-level ridge axis with development being inhibited somewhat
by moderate vertical shear.
Convection increased on the 10th with very cold cloud tops located
near the LLCC. A QuikScat pass prior to 1800 UTC indicated winds were
symmetric around the center with a westerly wind burst of 40 kts to
the north of the system. However, by 2100 UTC vertical shear had
increased and a substantial decrease in the deep convection was noted;
therefore, JTWC downgraded the development potential to poor. The
weakening trend was only temporary and JTWC re-upgraded the development
potential to fair again at 1100 UTC on 11 February. The shearing had
decreased significantly and scatterometer and microwave data indicated
the existence of a well-defined LLCC. Perth initiated gale warnings
at 11/0400 UTC due to strong monsoonal winds of up to 40 kts well to
the north of the depression's center. At 0200 UTC on the 12th JTWC
issued another Formation Alert for the system, and at 0600 UTC Perth
upgraded the LOW to Tropical Cyclone Vincent. Vincent was centered
at the time about 500 nm northwest of Onslow, moving northwestward
at 6 kts.
B. Track and Intensity History
------------------------------
After being upgraded to a tropical cyclone about 500 nm northwest of
Onslow, Vincent was initially quasi-stationary, then began to move
east-southeastward toward the Western Australian coastline. The
cyclone passed about 400 nm north of Onslow at 0400 UTC on 13 February.
The intensity (10-min avg winds) remained constant at around 40-45 kts
on 13 and 14 February. By 2200 UTC on the 14th Vincent had reached a
point about 125 nm northwest of Broome when it suddenly intensified to
55 kts. The cyclone then turned southward toward the coast but began
to collapse rapidly in the monsoon trough as it neared the shoreline.
The mean winds dropped to 50 kts by 15/1000 UTC and to 40 kts two hours
later. Perth issued their final advice at 15/1200 UTC, locating the
rapidly weakening cyclone about 150 nm west of Broome. JTWC issued
a final warning at 1800 UTC, relocating the 30-kt center inland about
175 km south of Broome.
The estimated maximum 10-min avg winds in Tropical Cyclone Vincent
were 55 kts from 14/2200 UTC through 15/0400 UTC. The minimum
estimated central pressure was 980 mb for the same period.
C. Meteorological Aspects
-------------------------
Tropical Cyclone Vincent presented a sheared appearance in satellite
imagery throughout its lifetime. On the 12th, shortly after the system
had been named, SSM/I data revealed a partially-exposed LLCC east of
the deep convection while a 200-mb analysis indicated the development
of a weak anticyclone aloft over the cyclone. Animated water vapor
imagery indicated that outflow was somewhat restricted to the south
but good over the northern semicircle. Strong equatorial westerlies
to the north were the primary influence on Vincent's steering, causing
its general east-southeasterly track. By 0600 UTC on the 13th the
LLCC was fully-exposed with deep convection displaced approximately
125 nm to the west of the center. Most of the satellite CI estimates
mentioned in the JTWC warnings were running around 30-35 kts for most
of Vincent's life, although one estimate reached 45 kts at 13/1800 UTC.
The JTWC warning at 14/0600 UTC alluded to a synoptic observation of
35 kts, but no information was given regarding the location of the
report. Vincent presented a somewhat more organized appearance at
1800 UTC on 14 February with deep convection located about 7 nm west
of the partially-exposed center. This convective blowup featured a
very large area of cold cloud tops of -90 C and colder, and likely was
the main consideration in Perth's increase in the cyclone's estimated
intensity to 55 kts at 2200 UTC. As late as 0600 UTC on the 15th JTWC
was still forecasting Vincent to intensify as it approached landfall,
but of course shortly afterward the cyclone began to collapse rapidly.
Wind gusts to 40 kts and rainfall amounts to 100 mm were recorded at
several Kimberley and Pilbara coastal stations as the ex-cyclone made
landfall.
NOTE: The information on the convective blowup described above came
from an e-mail by Ray Zehr. In a reply to him, John McBride pointed
out that all this occurred within radar range and that there was very
little precipitation under the huge cold anvil. Also, the LLCC was
still apparent off to the side in visible imagery, so the large area
of -90 C cloud tops was not over the system's center.
D. Comparisons Between Perth and JTWC
-------------------------------------
JTWC's tracking coordinates agreed very closely with those issued
by Perth. However, intensity-wise JTWC was well under Perth's
estimates for Tropical Cyclone Vincent. The highest MSW (1-min avg)
assigned by JTWC was 35 kts (although the 13/1800 UTC warning mentioned
one CI estimate of 45 kts). Perth's peak 10-min avg wind estimate of
55 kts would correspond to a 1-min avg MSW of at least 60 kts.
E. Damage and Casualties
------------------------
The author has received no reports of any damage or casualties
resulting from Tropical Cyclone Vincent.
***********************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for February: 1 tropical LOW **
2 tropical cyclones of gale/storm intensity
1 severe tropical cyclone (hurricane)
** - system moved eastward into the South Pacific basin/JTWC estimated
35-kt winds
The primary sources of information for Northeast Australia/Coral Sea
tropical cyclones are the warnings and bulletins issued by the TCWCs
at Darwin, Northern Territory, and Brisbane, Queensland. 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. References to sustained winds should be understood as being
based on a 10-min averaging period unless otherwise noted.
Again, a special thanks to Patrick Hoareau for preparing and sending
me the tracks for the tropical cyclones. Also, much of the information
below on meteorological observations and damage/casualties was provided
by Jeff Callaghan of the Brisbane TCWC and Mark Kersemakers of the
Darwin TCWC. A special thanks to these gentlemen for sending me this
information. More information can be found at the following URL:
http://www.bom.gov.au/inside/services_policy/public/sigwxsum/
sigwmenu.shtml>
Carl Smith, a cyclone enthusiast who lives on Queensland's Gold
Coast, has a website which contains a great amount of information on
tropical cyclones. The URL is: http://www.ace-net.com.au/~carls/>.
Following are some URL's where satpic animations and maps can be
found for individual cyclones:
http://cyclones.www9.50megs.com/2001/TCWinsome.html>
http://cyclones.www9.50megs.com/2001/TCVincent.html>
http://cyclones.www9.50megs.com/2001/TCWylva.html>
http://cyclones.www9.50megs.com/2001/TCAbigail.html>
Northeast Australia/Coral Sea
Tropical Activity for February
------------------------------
The very active Madden-Julian Oscillation phase which marched across
the South Indian Ocean during January reached the region of northern
and northeastern Australia by early February. The entire Southern
Hemisphere tropics lying east of longitude 135E had not seen a single
tropical cyclone development prior to February, but during the month
six named cyclones formed: three in the Australian region and three
in the South Pacific basin. As the month opened a LOW of non-tropical
origin was buffeting southeastern Queensland and northeastern New South
Wales, causing rough seas and heavy rainfall which led to significant
flooding. (A report on this LOW was included in the January summary.)
Around mid-month a tropical LOW formed in the eastern reaches of the
Australian region but moved eastward into the Fiji AOR where it was
designated as Tropical Depression 07F. (JTWC also issued three
warnings on this system as Tropical Cyclone 10P.) More information on
this depression is given below.
The three named tropical cyclones--Winsome, Wylva, and Abigail--all
made landfall in northern Australia. Remarkably, all three systems
maintained impressive, well-defined cloud systems after they had been
over land for several days. At times they almost appeared to be
intensifying over the desert. One could say, in a sense, that they
were "Survivors in the Australian Outback"! In addition to all the
systems thus mentioned, the Brisbane TCWC issued gale warnings on
19 February on a surface LOW accompanying an upper-level LOW which
moved westward from east of longitude 160E near the 28th parallel.
This system did not appear to have any tropical characteristics and
no track was included in the cyclone tracks file.
Tropical Cyclone Winsome (TC-08P)
8 - 11 February
----------------------------------
A. Origins
----------
The daily TWO issued by the Darwin TCWC on 7 February mentioned an
active monsoon trough and the expectation for a tropical LOW to
develop. A LOW had formed by 8 February in the southeastern Arafura
Sea about 350 nm east-northeast of Darwin with persistent convection
and an elongated LLCC. CIMSS wind products indicated weak vertical
shear, and animated water vapor imagery and a 200-mb analysis indicated
a developing anticyclone over the system. Both JTWC and Darwin
assessed the development potential for the LOW to be moderately good.
At 1600 UTC on the 9th JTWC issued a Formation Alert as the system had
shown improved organization during the past several hours with a
developing convective band east of the LLCC. There was also some deep
convection located west of the center in the monsoon trough, and the
LOW was underneath an anticyclone with good outflow and weak vertical
shear. The system continued to slowly develop as it drifted south and
southwest into the Gulf of Carpentaria and was named Tropical Cyclone
Winsome at 1200 UTC when it was located just north of Groote Eylandt.
B. Track and Intensity History
------------------------------
Winsome was located about 25 nm north-northeast of Alyangula when
it was named as a cyclone. The maximum sustained winds (10-min avg)
were estimated at 40 kts (based on the advices issued by Darwin).
Winsome passed between the island and the mainland before making
landfall near Numbulwar (110 km north-northeast of Port Roper) early
on the 11th (about 10/1800 UTC). By 11/0000 UTC Winsome was inland
about 40 km northwest of Port Roper and weakening. As a tropical LOW
the remnants of Winsome persisted for a further five days as it
traversed the Northern Territory, finally decaying over central Western
Australia on the 16th as it merged with the remnants of Tropical
Cyclone Vincent. (More on the overland phase of Winsome below.)
The maximum sustained (10-min avg) winds in Tropical Cyclone Winsome
were estimated at 40 kts from 10/1200 UTC through 11/0000 UTC as the
storm was making landfall. The estimated minimum central pressure was
980 mb at 1200 and 1800 UTC on 10 February.
C. Meteorological Aspects
-------------------------
Typical of most tropical cyclones developing in a monsoon trough,
the tropical LOW which developed into Winsome initially displayed a
rather broad circulation. The first JTWC warning on the developing
cyclone at 10/0600 UTC described it as a broad system with three
separate bands of convection and possible multiple LLCCs. At 1100 UTC
on the 11th, after Winsome had made landfall, the JTWC warning noted
that a strong band of convection was wrapping around the the southern
side of the LLCC.
Patrick Hoareau sent me two observations he'd located on the web.
At 10/1500 UTC Northeast Island (13.6S, 136.9E), close to the center
of Winsome, recorded a SLP of 988 mb with sustained winds of 18 kts
from the north. At 10/1530 UTC Centre Island (15.8S, 136.8E), located
generally to the south of the center, reported a SLP of 995 mb with
sustained southeasterly gales of 38 kts with higher gusts. (A special
thanks to Patrick for sending me the observations.)
D. Comparisons Between Darwin and JTWC
--------------------------------------
The center position coordinates from the four JTWC warnings agreed
closely with Darwin's track. Also JTWC's MSW (1-min avg) estimates
compared favorably with Darwin's. The peak MSW from JTWC of 45 kts
is in excellent agreement with Darwin's maximum 10-min mean wind of
40 kts, although the JTWC warning in which the 45 kts was estimated was
issued after Winsome had already moved inland. However, the exact time
of landfall (and presumably the cyclone's peak intensity) came in
between the JTWC warnings at 10/1800 and 11/0600 UTC.
E. Damage and Casualties
------------------------
One death was attibuted to Tropical Cyclone Winsome--a fisherman was
lost from his vessel near Maria Island at the mouth of the Roper River.
Two men were rescued after eight hours in a life raft when their
trawler capsized in the Gulf of Carpentaria near Karumba. Falling
trees brought down power lines in Alyangula, and there was some storm
surge flooding and damage there and at Numbulwar and Nhulunbuy. In
Darwin strong winds and severe wind gusts felled trees onto power
lines, causing blackouts, road accidents and damaging cars as the
remnants of Winsome moved south of the Top End on the 12th and 13th.
Large swells combined with high tides to produce coastal erosion and
dangerous conditions at Darwin beaches. One man was rescued after
spending 20 hours in Darwin Harbour clinging to mangrove trees after
his dinghy was swamped in rough seas.
Heavy rain caused flooding in many parts of the Northern Territory,
cutting the Victoria and Buntine highways as well as access roads to
Batchelor, Borroloola, and Dagaragu. The flooding also led to the
closure of many National Parks around the Top End. The Daly River
community was threatened but no evacuations were necessary. Two
cars were lost attempting to cross a flooded river near Timber Creek.
F. "Landphoon" Winsome
----------------------
In northern Australia, moreso than in any other place in the world,
tropical cyclones seem to maintain well-defined cloud systems over land
for extraordinary periods. Back in December the remnants of Tropical
Cyclone Sam brought large-scale rain for almost two weeks across the
northern portion of the continent. During February all three tropical
cyclones which made landfall along the Gulf of Carpentaria coastline
maintained themselves for several days while moving slowly across the
Northern Territory and into the eastern portion of Western Australia.
An infrared picture of Winsome taken at 15/1732 UTC shows a nice curved
band wrapped around the center enough to be considered a banding eye.
This feature also is evident in a visible picture taken at 15/2230 UTC.
(Such a feature was also seen with the remnants of Abigail several days
after making landfall--see summary of Abigail below.)
Two basic questions which this phenomenon raises are: (1) Are strong
surface winds still present? and (2) What factors help the ex-cyclones
to maintain themselves so well? An e-mail from Chris Landsea addresses
the first question. Chris points out that increased roughness lengths
over land mean that the winds would be reduced on the order of 20%
below values expected for the same central pressure over water. Also,
since the isothermal inflow in the boundary layer would not be
maintained over a very dry land area with very little capacity to
provide much sensible or latent heat flux, the "landphoons" are likely
cold-cored in the lower troposphere. This stability in the lower
levels would tend to reduce the ability of the circulation to maintain
strong surface winds.
As for what mechanisms help the systems maintain their circulations
so well over land, several suggestions have been proposed. Noel
Davidson suggests that a very active large-scale monsoon over northern
Australia is a major player by helping to reduce the effects of
of vorticity advection which might normally act to run the systems
down; also, the large-scale monsoon circulation could help to supply
moisture from a remote source (i.e., the Timor and Arafura Seas).
John McBride speculates that when there is a good, strong monsoon
trough at fairly high latitudes, the large-scale dynamics maintaining
the trough help to maintain the monsoon depressions/ex-cyclones also.
Another factor, especially in the case of Abigail, could be the
absolutely waterlogged northern regions with high surface temperatures.
Carl Smith wrote that many places across much of northern Australia had
received record rainfalls in the months leading up to the February
cyclone outbreak, and much of the terrain is as flat as a billiard
table, so run-off is slow. This could conceivably be an additional
source of moisture for the circulations of the ex-cyclones.
Tropical Cyclone Wylva
15 - 16 February
----------------------
A. Origins
----------
On 14 February a weak tropical LOW over the Cape York Peninsula
moved out over the waters of the eastern Gulf of Carpentaria. Both
Brisbane and JTWC mentioned the LOW in their respective Tropical
Weather Outlooks. Convection was developing in the monsoon trough
and synoptic data indicated that a LLCC might be located beneath
the convection. Brisbane assigned the system a high potential for
tropical cyclone development after 48 hours. The STWO from JTWC
at 1300 UTC on the 15th mentioned that a recent QuikScat pass had
indicated a well-defined LLCC with light winds near the center and
winds of 20-25 kts around the periphery. The system was under weak
to moderate vertical shear and JTWC upgraded the development potential
to fair.
JTWC issued a Formation Alert at 16/0030 UTC as a QuikScat pass
indicated 30-kt winds associated with the LLCC, which had persistent
and organizing convection. JTWC never issued any warnings on this
system, but the Brisbane TCWC upgraded the LOW to Tropical Cyclone
Wylva at 0000 UTC on 16 February.
B. Track and Intensity History
------------------------------
Wylva was centered approximately 100 nm northwest of Mornington
Island when it was named as a tropical cyclone. The system moved
westward and crossed the southern Gulf of Carpentaria coastline later
on the 16th just west of the Northern Territory-Queensland border as
a weak Category 1 cyclone. By 1200 UTC Wylva was inland and weakening
about 85 km south-southeast of Port McArthur. The cyclone decayed into
a tropical LOW which moved steadily across the Northern Territory for
the next few days, finally decaying over the Pilbara region of Western
Australia on the 22nd. Like Winsome before it and Abigail afterwards,
Wylva maintained its cloud structure quite well over the Australian
continent, but was not quite as impressive-looking after several days
over land as were the other two ex-cyclones.
The minimum estimated central pressure in Tropical Cyclone Wylva was
990 mb at 0000 and 0600 UTC on 16 February. The maximum 10-min mean
winds were estimated at 40 kts during the same period.
C. Meteorological Aspects
-------------------------
The only meteorological observations I have available on Wylva were
sent to me by Jeff Callaghan. The strongest winds at the Centre Island
AWS were 260/30 kts (10-min avg) at 16/0100 UTC while the lowest SLP
of 994.6 mb occurred at 0700 UTC. Jeff adds that "the westerly winds
there were strange as the low-level centre was northeast of the
station. The situation was complex with an apparent eye on radar
(maybe a middle-level centre) coming ashore and leaving the low-level
centre behind. These westerly winds were also evident at an adjacent
station."
A buoy (WMO 52625) moored near 14.6S, 138.5E reported peak winds of
280/28 kts (10-min avg) at 1851 UTC on the 15th. The lowest SLP of
995.3 mb occurred from 1736 to 1809 UTC. Mornington Island's lowest
SLP was 997.1 mb at 15/1800 UTC with the strongest sustained wind only
15 kts. QuikScat data showed 40-kt westerlies (non-rain affected)
north of Centre Island near latitude 15S at 2100 UTC on 15 February.
D. Damage and Casualties
------------------------
Heavy rain from the remnants of Wylva produced a record flood on the
Victoria River which inundated the Kalkarindji, Daguragu and Pigeon
Hole communities. Around 700 people were evacuated to a temporary tent
city in Katherine for several weeks. Damage estimated at $13 million
(Australian) was caused to the community infrastructure, including
access roads and bridges, many houses, the power station, police
station and health clinic at Kalkarindji. The community of Borroloola
and surrounding outstations in the Gulf country were isolated for an
extended period, requiring aircraft food drops to stranded residents.
Floodwaters also threatened the McArthur River mine and township,
Coolibah Station and crocodile farm, Timber Creek town, Victoria River
Downs and the Victoria River Roadhouse. The Victoria Highway between
the Northern Territory and Western Australia was cut from the 13th to
the 28th, and the Buntine and Carpentaria Highways were also cut for
extended periods.
Tropical Depression (TC-10P / TD-07F)
16 - 18 February
--------------------------------------
This system spent most of its short life east of longitude 160E
in the South Pacific basin, but since it actually originated in the
Coral Sea in Brisbane's AOR, I am covering it here. Normally I do
not give full coverage to tropical depressions, only to those systems
which, as best I can determine, are of nominal tropical character and
have a peak 1-min avg MSW of 35 kts or greater. Since JTWC did
estimate 35-kt winds for this depression, I have included a separate
report on the system, although based upon the remarks in the JTWC
warnings, there are perhaps grounds for doubting whether the system
actually reached that intensity.
A. Origins
----------
A Tropical Disturbance Summary from Nadi, Fiji, on 15 February
mentioned the existence of a disturbance in the Coral Sea. The TWO
from Brisbane also made reference to the system. JTWC picked up on
the system in its STWO on the 16th, noting that animated visible and
infrared satellite imagery depicted scattered convection around an
exposed LLCC and that a recent QuikScat pass had indicated winds of
15-20 kts. CIMSS satellite-derived wind products indicated weak shear
with fair outflow, so the development potential was rated as fair.
Brisbane began issuing gale warnings at 0100 UTC on 16 February with
the center of the LOW well over 600 nm off the Queensland coast, east-
northeast of Townsville. The system began moving eastward and Nadi
assumed responsibility for issuing the gale warnings at 1200 UTC after
the center had crossed 160E, designating the system as Tropical
Depression 07F. JTWC issued a Formation Alert at 16/1430 UTC since
convection had continued to organize around the partially-exposed LLCC.
B. Track and Intensity History
------------------------------
JTWC issued their first warning at 17/0000 UTC with the center
located approximately 275 nm northwest of Noumea, New Caledonia. The
warning intensity was estimated at 35 kts, but this was based on CI
numbers of 30 and 35 kts, as were the subsequent two warnings, so the
system never attained a solid Dvorak rating of T2.5. The depression
continued moving east-southeastward, and the final JTWC warning at
0000 UTC on the 18th placed the center about 75 nm north-northeast
of Noumea.
The maximum 1-min avg MSW estimated by JTWC was 35 kts. The lowest
central pressure estimated by Nadi was 995 mb at 17/1800 UTC. The
gale warnings issued by the Nadi TCWC never indicated that gales were
actually occurring, but warned of the possibility of gales developing
during the forecast period.
C. Meteorological Aspects
-------------------------
This tropical system presented a sheared appearance with a fully-
exposed LLCC throughout most of its life. The initial JTWC warning
indicated that some deep convection was developing about 10 nm south-
east of the LLCC, but convection never became established over the
center. Remarks in the 17/1200 UTC warning noted that an upper-level
analysis indicated a polar front jet finger with 50-kt winds over the
region. By the time the final warning was issued at 18/0000 UTC the
depression exhibited a poorly-defined fully-exposed LLCC with rapidly
weakening convection displaced about 65 nm east-southeast of the
center. A 200-mb analysis indicated strong northwesterly flow of
25-45 kts over the region associated with the polar jet finger.
D. Damage and Casualties
------------------------
The author has learned of no damage or casualties resulting from
Tropical Depression 07F (TC-10P).
Severe Tropical Cyclone Abigail (TC-12P)
22 - 27 February
-----------------------------------------
A. Origins
----------
Brisbane issued a TWO on 21 February which mentioned that a broad
area of low pressure lay across the northern Coral Sea. A High Seas
warning issued at 0800 UTC on the 22nd indicated that a complex area
of low pressure lay over the Coral Sea with two centers of about
1001 mb: one near 12.0S, 157.0E and the other near 17.5S, 154.0E.
Over the next 24 hours the two LOWs were expected to interact with
a 999-mb center that was forecast to develop near 15.0S, 152.0E by
23/0600 UTC. JTWC issued a STWO at 22/2100 UTC which indicated that
a partially-exposed LLCC was located approximately 550 nm east-
northeast of Townsville with persistent deep convection displaced
west-northwest of the center. Synoptic data indicated that sustained
surface winds were running around 15-20 kts, but one report was
received of 28-kt winds about 60 nm west-northwest of the center under
the deep convection. The LOW was located north of the subtropical
ridge axis under moderate easterly flow.
JTWC issued a Formation Alert at 23/0500 UTC as deep convection
continued to build over the partially-exposed LLCC. A 200-mb analysis
revealed an upper-level ridge paralleling the east coast of Australia
from an upper-level HIGH situated southeast of New Caledonia. Late on
the 23rd/early on the 24th (local time) the LOW was moving westward at
13 kts toward the Queensland coast. The Brisbane TCWC forecast that
the system would slow down and intensify as it approached the coast.
Shortly before reaching the coast, the system did exhibit a sudden
intensification--Tropical Cyclone Abigail was christened at 24/0000 UTC
(10:00 am EST) with the center located about 30 nm (60 km) east-
northeast of Cairns. (JTWC did not issue warnings during this phase
of Abigail's life, although a second Formation Alert was issued at
0200 UTC. This Alert noted an increase in deep convection near the
center but cited synoptic reports which indicated a circulation with
maximum winds of 25-30 kts.)
B. Track and Intensity History
------------------------------
During the first phase of its life Abigail was a tropical cyclone
for only three hours. The cyclone crossed the coast about 30 km
northwest of Cairns over the northern Cairns beaches (Palm Cove and
Ellis Beach) around local noon on the 24th. By 1:00 pm (0300 UTC)
Abigail was inland and had been downgraded to a LOW, moving westward at
5 kts. The remnant LOW continued to move westward, crossing the base
of the Cape York Peninsula, and by 25/0600 UTC had emerged into the
Gulf of Carpentaria about 75 nm east of Mornington Island. JTWC
issued a Formation Alert at 25/1300 UTC. Convection had persisted
northwest of the LLCC while the system continued to be sheared by
upper-level easterlies.
The LOW was upgraded once more to Tropical Cyclone Abigail at
1800 UTC on 25 February with the center located about 60 nm northeast
of Mornington Island. The system had moved somewhat to the northwest
(or else the center had shifted as it reformed). Abigail began to
intensify fairly rapidly: winds reached 50 kts by 26/0000 UTC and
had climbed to the peak of 65 kts by 1200 UTC when the cyclone was
centered 45 nm west of Mornington Island--making Abigail a Category 3
cyclone on the Australian Cyclone Severity Scale. After being
renamed as a cyclone, Abigail commenced on a southwesterly track which
carried it inland near the Northern Territory-Queensland border around
2:00 am CST on the 27th (26/1630 UTC). The point of landfall was
about 150 km southeast of Port McArthur or 150 km west of Mornington
Island township. As it approached the coast Abigail weakened slightly
into a Category 2 cyclone--the maximum 10-min avg winds were likely
around 50-55 kts as the center moved inland.
After making landfall the weakening cyclone resumed a westerly track
across the Northern Territory. Abigail weakened into a tropical LOW
south of Borroloola but continued to traverse the Northern Territory
during the next three days along a track close to that followed by the
remnants of earlier Tropical Cyclones Winsome and Wylva. Also, in a
manner similar to that of the two preceding cyclones--especially
Winsome--Abigail maintained a very well-defined cloud system in
satellite imagery for several days. Carl Smith sent me a few enhanced
infrared images from 2 and 3 March, and these reveal a still very
well-organized cloud pattern. Indeed, the image from 02/2332 UTC
shows a feature which looks like a small CDO with a well-defined eye!
However, the center of this "eye" is rather cold as compared to the
underlying surface (land). (Visible and TRMM microwave images sent
by Mark Lander also show this "eye" feature very distinctly.) The
third image (at 03/1132 UTC) does not show the eye-feature, but a
large, well-defined swirl shows up nicely. (A more in-depth discussion
of these Australian "landphoons" is included in the summary of Winsome
above.)
During the first, brief phase of Abigail's life, the maximum 10-min
avg sustained wind was 40 kts, recorded at the Green Island AWS, with
an attendant pressure of 994.1 mb, at 24/0000 UTC. A slightly lower
pressure of 992.7 mb was measured at 0028 UTC. Over the Gulf of
Carpentaria Abigail reached its peak intensity of 65 kts around
1200 UTC on 26 February. The estimated minimum central pressure was
965 mb, based on the Brisbane tropical cyclone advices.
C. Meteorological Aspects
-------------------------
As Tropical Cyclone Abigail strengthened initially and moved inland
near Cairns, the Green Island AWS (WMO 95289), located 27 km northeast
of Cairns, recorded sustained gale-force winds for about 1-1/2 hours,
peaking at 40 kts (10-min avg) from the south at 24/0000 UTC. The
lowest pressure there of 992.7 mb was measured at 24/0028 UTC when
the wind was 29 kts sustained, gusting to 47 kts. The Cairns Airport
reported a minimum pressure of 995.9 mb at 24/0041 UTC with the peak
wind gust of 44 kts occurring at 0100 UTC. Daintree Village and Low
Isles recorded 241 mm and 228 mm of rainfall, respectively, in the
24 hours ending at 9:00 am EST on the 24th. Several other locales
recorded rainfall amounts varying between 100 and 200 mm.
After re-intensifying in the Gulf of Carpentaria, the eye of Abigail
passed over Mornington Island township around 7:00 pm EST (0900 UTC)
on 26 February. The maximum sustained 10-min mean wind recorded by
the AWS there was 031/38 kts at 26/1000 UTC (gusting to 56 kts) while
the peak gust of 64 kts was recorded at 1020 UTC. However, Jeff
Callaghan points out that the AWS site is surrounded by large trees
and it very close to a building, and is known to under report the wind
speed. Before the eye passed over the station, an observer with a
hand-held anemometer recorded a gust of 64.5 kts. At the time of the
peak 64-kt gust recorded by the AWS, the same observer estimated the
peak gusts to be in excess of 80 kts, so it appears likely that the
AWS under reported the wind by around 20 kts. The lowest pressure
measured by the AWS was 973.7 mb at 26/0820 UTC, but a barograph
located about 2 km west of the AWS recorded the pressure in the eye
at 968.5 mb around 0900 UTC. At Mornington Island the storm surge
reached 0.5 m above the highest astronomical tide. Further east at
Karumba there was a 1.2 m storm surge.
The JTWC warning at 26/1800 UTC indicated that Wollogorang reported
35-kt sustained winds from the southeast at 1700 UTC. The 27/0600 UTC
warning mentioned a synoptic report about 60 nm north of Abigail's
center (WMO 94248) which indicated 27-kt sustained northwesterly winds.
D. Comparisons Between Brisbane/Darwin and JTWC
-----------------------------------------------
JTWC issued no warnings for the Coral Sea phase of Abigail's
history, although the Formation Alert at 24/0200 UTC indicated winds
of up to 30 kts. The measured 40-kt 10-min mean wind at Green Island
would imply a peak 1-min avg wind of around 45 kts as Abigail was
moving inland near Cairns. Over the Gulf of Carpentaria the track
coordinates from JTWC were in very close agreement with those from the
Australian warning centres. JTWC's MSW (1-min avg) estimate at
26/0600 UTC (55 kts) was a little lower than Darwin's 60-kt 10-min avg
estimate, which would convert to a MSW of around 70 kts. However,
the peak intensity of 65 kts at 26/1200 UTC fell in between the
12-hourly warning times for JTWC. The 65-kts 10-min avg would equate
to a 1-min avg MSW of about 75 kts. According to Mark Lander,
objective Dvorak numbers reached T4.5, which would correlate well with
a MSW (1-min avg) of 75 kts.
E. Damage and Casualties
------------------------
The impact of Abigail in the Cairns area was minimal. There was
some local flooding and trees downed at Edge Hill and in the northern
suburbs. The damage estimate in and around Cairns was put at $83,000.
The damage estimate for Mornington Island was considerably higher
at $245,000. Numerous trees were downed, many buildings experienced
roof damage, a water tank was blown off its stand, numerous television
aerials were blown away, electrical services and floor coverings were
damaged due to water entry, almost all buildings lost their aluminium
louvred sun shades, plus much damage was caused by flying debris.
As the remnants of Abigail moved westward across the Northern
Territory, heavy rains compounded the misery in the already waterlogged
region. These rains added to the flood waters in the Gulf country and
the Victoria River district, prolonging the pre-existing disruption to
communities in the region.
***********************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for February: 1 tropical depression **
2 tropical cyclones of gale/storm intensity
1 tropical cyclone of hurricane intensity
** - system originated in Australian Region west of 160E/JTWC estimated
35-kt winds
Most of the information presented below was taken from the
operational warnings and advisories issued by the Fiji TCWC at Nadi.
References to sustained winds imply a 10-minute averaging period
unless otherwise noted.
The reports on Tropical Cyclones Oma, Paula and Rita were written
by Alipate Waqaicelua, Chief Forecaster at the Nadi TCWC, with only
minimal editing by myself. A very special thanks to Alipate for
preparing and sending the reports to me (as well as the tracks for
the cyclones.) A special thanks also to Steve Ready of the New
Zealand Meteorological Service for sending me some damage reports
from islands affected by Tropical Cyclone Paula.
South Pacific Tropical Activity for February
--------------------------------------------
After lying quiet through the entire first half of the nominal
tropical cyclone season, the tropics of the South Pacific came alive
during the third week of February, producing three named tropical
cyclones, one of which was a rather intense hurricane. Around mid-
month a tropical depression formed in Brisbane's AOR and moved east-
ward into the South Pacific proper. Nadi referred to this system as
TD-07F while JTWC designated it as TC-10P. A report on this system
is given in the section covering Northeast Australia and the Coral
Sea. Tropical Cyclones Oma and Rita formed at fairly high latitudes
well east of the Dateline, especially Rita, whereas intense Tropical
Cyclone Paula formed deep in the tropics to the northwest of Fiji.
Paula passed directly over some of the islands of Vanuatu where it
was quite destructive, and brushed the islands of Fiji with gales as
it passed to the south. Also, Mark Lander, in an e-mail, mentioned
the existence of a subtropical cyclone near 31S, 145W around 0330 UTC
on 19 February. Scatterometer data indicated extensive gales
associated with this subtropical cyclone. No track was given for this
system in the February tracks file.
Tropical Cyclone Oma (TC-11P / TD-08F)
20 - 22 February
---------------------------------------
A. Origins
----------
The first tropical cyclone of the 2000/2001 tropical cyclone season
in RSMC Nadi's AOR developed from an upper-level cut-off low (TUTT)
which spun its way down to the surface about 300 nm west-northwest of
Rarotonga in the Cook Islands around 19/1800 UTC. MSL charts on the
18th had begun to show signs of the circulation reaching the surface.
Development was occurring over warm SSTs of around 30 C and within a
weakly-sheared environment. Overnight on the 20th, Tropical
Depression 08F went through a very rapid development phase with
convection erupting over the LLCC (exposed during the daylight hours)
and overall organisation increasing significantly. Cloud tops steadily
cooled and increased spatially while cold convective bands also began
to wrap tightly around the LLCC. The system was named Tropical Cyclone
Oma around 20/1800 UTC while located about 180 nm southwest of
Rarotonga and moving southeastward at about 10 to 15 kts.
B. Track and Intensity History
------------------------------
Oma accelerated to about 20 kts toward the southeast after being
named while rapidly intensifying to storm intensity (48 kts) at
21/0000 UTC. Peak intensity of 55 kts was attained six hours later
(at 21/0600 UTC). As the cyclone was rapidly moving towards New
Zealand's AOR under a strong northwesterly steering regime, primary
responsibility for warnings was subsequently handed over to RSMC
Wellington, which commenced issuance of warnings at 21/1200 UTC.
After moving south of the 25th parallel, Oma continued to move rapidly
toward the south-southeast and was declared extratropical at 1200 UTC
on 22 February when located over 1000 nm south-southeast of Rarotonga.
As noted above, the estimated peak intensity (10-min avg) for
Tropical Cyclone Oma was attained at 21/0600 UTC with the minimum
central pressure estimated at 980 mb. The MSW was dropped to 50 kts
at 21/1200 UTC but Wellington increased it back to 55 kts at 1700 UTC.
C. Meteorological Aspects
-------------------------
The first Special Weather Bulletin for Rarotonga and Mangaia in the
Southern Cooks was issued around 20/2053 UTC after gales suddenly
developed and extended farther out to the east and northeast sectors
against expectations. Maximum winds recorded at Rarotonga were gale
force with an unverified observation of storm intensity lasting only
about 15 minutes.
The JTWC warning issued at 21/0600 UTC mentioned a synoptic report
of 47 kts, but the location of this observation was not given. As seen
in satellite imagery, most of the deep convection remained in Oma's
eastern semicircle throughout most of its short life.
D. Comparisons between Fiji/New Zealand and JTWC
-----------------------------------------------
JTWC issued only four warnings on Oma, but the estimated position
coordinates agreed closely with the Southern Hemisphere TCWC's track,
except that the final JTWC warning at 22/0600 UTC placed Oma's center
about 90 nm east of Wellington's position, but the cyclone was already
beginning to lose its tropical structure at that time. As for
intensity, JTWC's 1-min avg MSW estimates in general were lower than
the maximum 10-min avg winds reported by Nadi and Wellington. The
peak of 55 kts would equate to a 1-min avg MSW of around 60-65 kts.
(This correlates well with Mark Lander's opinion that Oma reached
a Dvorak rating of T4.0 at its peak.)
E. Damage and Casualties
------------------------
In the report on Oma sent to me by Alipate, he indicated that no
official damage report had yet been received from Rarotonga. If any
information later becomes available, it will be reported in a future
summary.
Tropical Cyclone Paula (TC-13P / TD-09F)
25 February - 5 March
-----------------------------------------
A. Origins
----------
A tropical depression (TD-09F) was first identified embedded in an
active monsoon trough just south of the Solomons group, or about 210 nm
northwest of Espiritu Santo in Vanuatu at 25/1800 UTC and moving slowly
southeastward. At this time the system was lying under the 250-mb
outflow centre with minimal shear and SSTs around 30 C. Convection had
suddenly erupted close to the LLCC, though confined to the northern and
eastern quadrants, but immensely increased as compared to 24 hours
earlier. By 26/0000 UTC convective bands had begun to wrap around the
LLCC with increased curvature. Potential for development into a
tropical cyclone over the next 12 to 24 hours was subsequently raised
to "high" as convection steadily increased around the centre, with tops
cooling further. Atmospheric pressures at the surface, in turn, fell
steadily around the system. QuikScat and SSM/I data on the local
evening of the 26th confirmed that gales were persisting over the
northeastern semicircle.
B. Track and Intensity History
------------------------------
Consequently, at 26/1200 UTC, TD-09F was named Tropical Cyclone
Paula while located about 120 nm northwest of Espiritu Santo, Vanuatu.
The cyclone was then moving southeastward at about 10 kts with gales
confined to within 90 nm of the centre in the northeastern semicircle,
but still rapidly intensifying. At this time Paula also began to
describe a clockwise loop under a weak steering current. Six hours
later, at 27/0000 UTC, Paula reached the storm category with 50-kt
winds close to the centre. By 27/0600 UTC, after completing the loop,
the cyclone had developed a small CDO with a ragged eye-like feature.
At 27/1200 UTC hurricane intensity was attained as the eye was
becoming better defined with overall organisation and deep convection
increasing considerably. The cyclone was then located about 90 nm
northwest of Espiritu Santo and beginning to accelerate southeastward
as it continued to intensify.
Paula moved across Vanuatu, just north of the capital, Port Vila,
around 28/1200 UTC with peak winds (10-min avg) of 85 kts close to the
centre with a slightly cloud-filled eye. Special Advisories for
Vanuatu commenced around 25/2344 UTC when it was anticipated that
TD-09F would reach tropical cyclone status within the next 12 to 24
hours. The final one was issued at 0230 UTC on 1 March. In all,
fourteen Special Advisories were issued for Vanuatu at six hourly
intervals.
Fiji was first put on Tropical Cyclone Alert in the first Special
Weather Bulletin, issued around 28/0330 UTC, when it was anticipated
that Paula could move reasonably close to the country and possibly
cause damaging gale-force winds or stronger by early March 2nd. This
was later upgraded to a Tropical Cyclone Warning for Southwest Viti
Levu, Yasawa and Kadavu around 28/1730 UTC when the need was apparent.
Vatulele, Beqa and nearby smaller islands, as well as Lomaiviti and
Southern Lau, were later included in subsequent issues. At 0800 UTC on
March 1 the Gale Warning for Vatulele, Beqa, Kadavu and nearby smaller
islands was upgraded to a Storm Warning as Paula further intensified.
However, this was downgraded to a Gale Warning around 01/2000 UTC when
the cyclone was rapidly moving away from the area. The final Special
Weather Bulletin for Fiji was issued around 01/2300 UTC as the cyclone
raced away from the country. Altogether, there were eighteen Special
Weather Bulletins issued for Fiji. The closest Paula came to any part
of Fiji was around 01/1800 UTC when the cyclone passed about 90 nm
south-southwest of Kadavu island. The cyclone also reached its peak
around this time, reaching an intensity of 10-min avg winds of 90 kts
close to the centre.
After Paula had passed Fiji, it steadily accelerated southeastward
under the strengthening northwesterly steering current but into a very
strongly sheared environment. Weakening was rapid with the MSW
dropping from 90 kts to 60 kts in a period of 30 hours. Primary
responsibility for warnings was officially handed over to the
Wellington office at 03/0600 UTC with the cyclone at minimal hurricane
intensity and weakening further. Paula became extratropical at
04/0600 UTC when it was located about 850 nm east-northeast of the
northern tip of New Zealand.
Based on warnings from RSMC Nadi, Tropical Cyclone Paula was at its
peak intensity of 90 kts (10-min avg) from 1800 UTC on 1 March through
1200 UTC on the 2nd. The estimated minimum central pressure was 935 mb
at 01/1800 and 02/0000 UTC.
C. Meteorological Aspects
-------------------------
The JTWC warning at 1200 UTC on 28 February mentioned that Port Vila
in Vanuatu had reported sustained easterly winds of 29 kts at 0900 UTC.
Paula's center at that time was located about 25 nm north-northwest of
the city. Gales extended outward about 135 nm northeast of the center
and 100 nm elsewhere. Patrick Hoareau sent me an observation he'd
located: Lamap (16.4S, 167.8E) in Vanuatu reported sustained 45-kt
winds with a SLP of 980 mb at 1800 UTC on 27 February. Also, Patrick
passed along a report that the local weather station at Port Vila had
recorded sustained winds (presumably a 10-min avg) of 85 kts during
the height of Tropical Cyclone Paula. (A special thanks to Patrick
for sending me these reports.)
At its peak, around 0000 UTC on 2 March, Paula had become a rather
large, severe tropical cyclone. Gales extended outward to the north-
east 140 nm and 120 nm elsewhere, while 50-kt winds extended 65 nm
northeast of the center and 55 nm in other quadrants. A 01/2130 UTC
SSM/I pass revealed deep convection over the southern semicircle and a
primary band wrapping into the northwest quadrant. Paula was in a
region of moderate vertical shear, but a 200-mb analysis indicated
that the storm had maintained an anticyclone aloft and had
good outflow.
D. Comparisons Between Fiji/New Zealand and JTWC
------------------------------------------------
Center position coordinates issued by JTWC were in close agreement
with those contained in Nadi's and Wellington's warnings, although
the differences were slightly larger during the time when Paula was
weakening and undergoing extratropical transition. JTWC's 1-min avg
MSW estimates tended to be lower than the intensities reported by
Nadi after conversion from 10-min to 1-min winds. The peak 10-min
avg wind given in the Nadi warnings would translate into a 1-min avg
MSW of around 105 kts. The JTWC warning at 02/1200 UTC did refer to
a CI estimate of 102 kts, but since the system appeared to be in the
first stages of extratropical transition, the MSW was held at 90 kts.
E. Damage and Casualties
------------------------
The eye, or at least parts of the eyewall convection, passed over
Espiritu Santo, southern Malakula, Epi, the Shepherd group (including
Emae and Tongoa) and North Efate in Vanuatu between 27/1500 UTC and
28/1500 UTC. Many locally-styled houses, gardens and tree crops were
destroyed in those areas and in addition, many yachts in Port Vila were
either sunk or set adrift, and a number of small coastal ships were
forced aground. One death was reported in central Vanuatu. (The
above information came from Steve Ready.)
OCHA (Office for the Coordination of Humanitarian Affairs) reported
that the government of Vanuatu had declared Malampa and Shefa provinces
in central Vanuatu disaster areas. Damage was reported to 45-50% of
homes and gardens, 35% of water supplies, 20% of schools, 15% of
medical centers, and to 25% of other infrastructure items in those
provinces.
Although Paula passed to the south of Fiji, severe damage was
sustained in some parts of the nation, especially along coastlines
that were exposed to the surge and swells generated by the cyclone.
A number of homes were damaged or destroyed along the Coral (southern)
Coast of Viti Levu by strong winds and high waves. Additionally,
root crops, fruit trees and some sugar cane fields were reportedly
damaged. Minor landslides were also reported, and roads were closed
due to floods, fallen trees and sea-borne debris. Alipate reports
that a preliminary damage assessment in these areas estimated that
damage totalled around $2-3 million (Fijian). Some damage to
buildings and crops was also experienced in the Southern Lau group
in the eastern division of Fiji.
Finally, as Paula whizzed by southern Tonga on 2-3 March, the outer
circulation of the cyclone caused some damage. The Good Samaritan
Resort at Kolovai on the west coast of Tongatapu was extensively
damaged by pounding surf while a wharf on the nearby island of 'Eau
was badly damaged.
If any more damage figures become available later from areas
affected by Tropical Cyclone Paula, they will be reported in a future
summary.
Tropical Cyclone Rita (TC-14P / TD-10F)
28 February - 5 March
----------------------------------------
A. Origins
----------
A tropical disturbance was first identified on Nadi's MSL charts at
0000 UTC on 27 February, just southeast of Hao in the Tuamotu Group,
drifting slowly southeastward. At this time, the disturbance was
embedded in an active SPCZ and slightly north of a diffluent 250-mb
ridge. Through February 28th the system was significantly influenced
by southerly shear which displaced the canopy to the north and exposed
the LLCC to the south. However, overnight on the 28th, convection
began to develop close to the centre, against the shear and diurnal
variations. Meteo France in French Polynesia offered their opinion
to RSMC Nadi that gales of up to 45 kts were possibly present close
to the centre by 28/1200 UTC. SSTs were around 30 C, and with the
active eastward-progressing MJO cycle, potential for development into
a tropical cyclone was high. By 28/2000 UTC convection had continued
to increase about the centre with further cooling of cloud tops.
Tropical Depression 10F was then named Tropical Cyclone Rita while
located about 210 nm northeast of Mururoa (or 240 nm north-northwest
of Rikitea) and moving slowly southward under a northerly steering
regime.
B. Track and Intensity History
------------------------------
By 0000 UTC on 2 March, overall convective organisation showed
improvement under significant shear. A small CDO-type feature had
also begun to appear with tops cooling steadily. Based on this, the
intensity was increased to storm category at 02/0600 UTC as Rita
moved south-southeastward at about 5 kts. However, convective tops
warmed rapidly thereafter; subsequently, the system was downgraded to
gale force six hours later, at 02/1200 UTC, with the shear arresting
any further intensification.
After 02/1200 UTC Rita turned toward the south and was now exposed
to strong northwesterly shear at the 250-mb level. This was
corroborated by low-level cloud lines being exposed on the northwest
edge of the deep convection, which was now being displaced to the
southeast. Under the influence of the strong subtropical ridge
extending from the east, Rita was steered more south-southwesterly,
passing just northwest of Rikitea, on its way farther towards the
south. At this time, Rikitea reported a pressure of 990 mb with an
estimated wind of 45 kts. The cyclone maintained this track and gale
intensity as it moved into RSMC Wellington's AOR after 03/1800 UTC.
Rita maintained its circulation and identity as a cyclone for at least
another 36 hours after exiting Nadi's AOR. The system finally became
extratropical around 05/0600 UTC about 500 nm south-southwest of
Pitcairn Island. (NOTE: Information from Steve Ready indicated that
the 45-kt wind was recorded at 03/0000 UTC and that the reported
pressure was 993.8 mb.)
Tropical Cyclone Rita reached its peak estimated intensity of 50 kts
at 0600 UTC on 2 March, but quickly weakened to 35 kts six hours later.
The cyclone reached a secondary maximum of 45 kts (as estimated by
Wellington) at 0600 and 1200 UTC on 4 March. The minimum estimated
central pressure was 985 mb at 02/0600 UTC and also at 04/0600 UTC.
C. Meteorological Aspects
-------------------------
Tropical Cyclone Rita managed to maintain gale intensity for most
of its life under a strongly sheared environment. In the early stages,
gales were present only within the eastern semicircle. Rita's being
upgraded to a cyclone as early as it was was probably a result of the
change in the WMO Region 5 definition of a tropical cyclone that was
adopted at a meeting in Rarotonga last September. Formerly, a system
was not named as a cyclone until gales surrounded the center, but this
restriction was removed as sometimes depressions were well on their
way to becoming a hurricane before they received a name.
The only surface observation available to the author was the report
from Rikitea mentioned above (990 mb pressure and estimated wind of
45 kts). The JTWC warning at 03/0600 UTC mentioned that a recent
QuikScat pass had indicated a well-defined LLCC with winds of 35 to
40 kts.
D. Comparisons Between Fiji/New Zealand and JTWC
------------------------------------------------
Position estimates from JTWC in general agreed closely with those
from Fiji and New Zealand. The greatest discrepancy (84 nm) was on
5 March after Rita had become extratropical. As was the case with
Tropical Cyclones Oma and Paula, the JTWC 1-min avg MSW estimates
generally ran a little lower than Nadi's and Wellington's intensities
(after converting to 1-min avg equivalents). In particular, at
0600 UTC on 2 March, when Nadi reported the peak 10-min avg wind at
50 kts, JTWC estimated the MSW at only 35 kts. Also, Rita had already
been carried as a tropical cyclone for almost 24 hours when the first
JTWC warning was issued at 1800 UTC on 1 March.
E. Damage and Casualties
------------------------
As of yet no damage reports have been received from the Tuamotus.
If any information becomes available later, it will be reported in a
future summary.
***********************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the 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
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
February as an example: feb01.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: feb01.sum, for
example.
Back issues can also be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Tom Berg, Michael
Pitt, and Rich Henning):
http://australiasevereweather.com/cyclones/>
http://www.typhoon2000.com> OR http://www.geocities.com/taifun00/>
http://www.hurricanealley.net/>
http://www.qisfl.net/home/hurricanemike>
http://www.met.fsu.edu/gsc/Docs/Grads/henning/cyclones/>
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 2000 (1999-2000 season for the Southern
Hemisphere). Also, ATCRs for earlier years are available also.
The URL is: http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2000 Atlantic and Eastern North Pacific
tropical cyclones; also, preliminary storm reports for all the 2000
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>
Prepared by: Gary Padgett
E-mail: [email protected]
Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays)
***********************************************************************
***********************************************************************
|
Document: summ0102.htm
Updated: 29th December 2006 |
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