MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
JANUARY, 2006
First Installment
(For general comments about the nature of these summaries, as well as
information on how to download the tabular cyclone track files, see
the Author's Note at the end of this summary.)
SPECIAL NOTE: The January summary is being issued in two installments.
The first covers all the Northern Hemisphere basins, plus the South
Indian Ocean and Northwestern Australia. The second installment will
cover Northeastern Australia and the South Pacific Ocean.
*************************************************************************
JANUARY HIGHLIGHTS
--> Final Atlantic tropical storm of 2005 roams central Atlantic waters
in early January
--> First North Indian Ocean tropical cyclone of 2006 forms
--> Intense tropical cyclone forms in Mozambique Channel
--> Two cyclones form off Northwestern Australia while three cyclones
form in South Pacific
*************************************************************************
EXTRA FEATURE - INDEX TO MONTHLY AND EXTRA FEATURES FOR 2005
Beginning in May, 2000, I began including with each monthly summary
an extra feature which I called the Feature of the Month. Beginning
with July, 2005, I suspended these as a regular monthly item, but have
since included some extra features as time permits. Following is an
index to the regular Feature of the Month from January through June,
2005, plus the extra features included since July, 2005.
JAN - 2005 TROPICAL CYCLONE NAMES for the NORTHWEST PACIFIC BASIN
ALSO - Index to Feature of the Month Articles for 2004
FEB - INTRODUCING ANOTHER OUTSTANDING TROPICAL CYCLONE WEBSITE
ALSO - NORTH INDIAN OCEAN CYCLONE NAMES for 2005
MAR - WESTERN HEMISPHERE TROPICAL CYCLONE NAMES for 2005
ALSO - 2004 SEASONAL STATISTICS FOR THE ATLANTIC
AND NORTHEAST PACIFIC BASINS
APR - REVIEW OF GLOBAL TROPICAL CYCLONE TERMINOLOGY
MAY - WIND REPORTING CRITERIA (Results of 2003 survey)
JUN - A REVIEW OF THE 2004-2005 TROPICAL CYCLONE SEASON
FOR THE SOUTHERN HEMISPHERE
JUL - none
AUG - REPORT ON SEVERE SOUTH AMERICAN EXTRATROPICAL CYCLONES
SEP - SOUTHERN HEMISPHERE TROPICAL CYCLONE NAMES for 2005-2006
OCT - 2006 TROPICAL CYCLONE NAMES for the NORTHWEST PACIFIC BASIN
and for the NORTH INDIAN OCEAN
NOV - none
DEC - A REVIEW OF THE 2005 TROPICAL CYCLONE SEASON
FOR THE NORTHERN HEMISPHERE
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for January: 1 tropical storm **
** - system actually formed in late December
Atlantic Tropical Activity for January
--------------------------------------
As the year 2006 dawned, the first inter-annual tropical cyclone in
51 years was stirring waters of the east-central subtropical Atlantic.
Tropical Storm Zeta, which formed rather suddenly from a non-tropical
LOW on 30 December, continued operating until dissipation on 6 January,
generating a peak estimated intensity of 55 kts. Zeta was the first
Atlantic tropical cyclone to form in late December and continue into
the new year since Hurricane Alice of 1954-1955. The only other system
in the Atlantic Best Tracks database during the month of January is
a subtropical storm which formed in late January, 1978. The report
on Tropical Storm Zeta was included in the December summary.
*************************************************************************
NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180
Activity for January: No tropical cyclones
*************************************************************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for January: 1 tropical depression **
** - not treated as a tropical depression by JTWC
Northwest Pacific Tropical Activity for January
-----------------------------------------------
One tropical system formed in the Northwest Pacific basin during
January, as classified by JMA and PAGASA. A tropical depression formed
on 20 January roughly 300 nm east of the southernmost Philippine island
of Mindanao. JMA began including the system as a weak depression in
the summary section of their High Seas Bulletins. The depression moved
on a somewhat erratic northwesterly track toward the central Philippines
over the next few days. On the 23rd, as it was nearing the Philippines,
the system became slightly better organized and JMA classified it as a
30-kt tropical depression. Also, PAGASA initiated warnings on the
system, naming it Tropical Depression Agaton. Agaton crossed the
northern portion of Samar Island and the extreme southern tip of Luzon.
The system then weakened but continued to move westward into the South
China Sea. JMA continued to follow it for a few more days, but it had
dissipated by 27 January about halfway between southern Vietnam and
northern Borneo. JTWC did not classify Agaton as a tropical depression.
A graphic depicting the track of Tropical Depression Agaton may be
found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/WPAC/BT-IMAGES/2006-00W-AGATON.gif>
*************************************************************************
NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea
Activity for January: 1 tropical cyclone of gale intensity **
** - classified as as deep depression by IMD
Sources of Information
----------------------
Most of the information presented below is based upon tropical
cyclone warnings and significant tropical weather outlooks issued
by the Joint Typhoon Warning Center of the U. S. Air Force and
Navy (JTWC), located at Pearl Harbor, Hawaii. Occasionally some
information may be gleaned from the daily tropical weather outlooks
and other bulletins issued by the Indian Meteorological Department
(IMD), which is the World Meteorological Organization's Regional
Specialised Meteorological Centre (RSMC) for the basin.
The reported maximum sustained winds (MSW) are based on a 1-minute
averaging period, which is used by all U. S. civilian and military
weather services for tropical cyclone warnings. For synoptic
observations in the North Indian Ocean region, both 10-minute and
3-minute average winds are employed, but IMD makes no attempt to
modify the Dvorak scale for estimating tropical cyclone intensity;
hence, a 1-minute average MSW is implied. In the North Indian Ocean
basin JTWC usually does not initiate warnings until a system has
become well-organized and likely to attain tropical storm status
within 48 hours.
TROPICAL CYCLONE
(TC-01A)
13 - 17 January
------------------------------------
Tropical Cyclone 01A should probably be thought of as the final North
Indian Ocean cyclone of the active 2005 fall transition season. Starting
with Cyclonic Storm Pyarr in mid-September, TC-01A was the seventh system
to reach tropical storm intensity in the basin (although JTWC did not
regard Pyarr as a tropical storm). January tropical cyclones of gale
intensity are very infrequent in the North Indian Ocean, although one did
form in January of 2005--Cyclonic Storm Hibaru--along with another weaker
tropical depression. Prior to 2005, the last January tropical storm
in the basin was in 1991, and no tropical cyclones of hurricane
intensity have developed in the North Indian basin in the month of
January since at least 1981.
Even though it was interesting from a climatological standpoint,
TC-01A was quite insignificant meteorologically speaking. Peaking at
only 40 kts (per JTWC), the cyclone was quite short-lived and remained
over water throughout its lifetime. A STWO issued by JTWC at 0200 UTC
on 12 January noted that a persistent area of convection was located
approximately 170 nm south of Colombo, Sri Lanka, with cycling but
organized deep convection. Animated water vapor imagery indicated a
well-organized mid-level circulation but it was not evident that a LLCC
existed. Vertical wind shear was low and upper-level outflow moderately
good. A 12/0024 UTC QuikScat pass indicated a well-organized LLCC so
the potential for development was upped to 'fair' at 12/1800 UTC. Deep
convection continued to increase around the well-defined LLCC and JTWC
issued a TCFA at 0830 UTC on 13 January. The circulation center was
then estimated to be about 190 nm southwest of Colombo and observations
in the vicinity indicated sustained winds of 20 to 30 kts. A bulletin
issued by RSMC New Delhi (IMD) at 13/1200 UTC noted that a depression
had formed over the southeastern Arabian Sea.
The first of three JTWC warnings on TC-01A was issued at 1800 UTC
on the 13th, placing the center approximately 230 nm west-southwest of
Colombo, tracking toward the northwest at 12 kts. Associated convection
was still increasing and some modest intensification was forecast over
the next couple of days, followed by weakening as the system encountered
strong northerly flow in the central Arabian Sea. TC-01A reached its
peak intensity of 40 kts at 0600 UTC on 14 January when it was centered
about 355 nm west of Colombo. There had been no significant change in
convection, but water vapor imagery showed that the radial outflow was
becoming slightly fragmented. Only 12 hours later JTWC issued their
final warning on the system, which was then located about 550 nm west
of Colombo, moving west-northwestward at 16 kts. There had been a
significant decrease in deep convection and a 14/1348 UTC QuikScat
pass indicated that the LLCC had become poorly-defined. The MSW was
still estimated at 35 kts, but TC-01A was forecast to continue weakening
as it tracked into a less favorable environment. The residual LLCC
continued to track westward into the south-central Arabian Sea over the
next 2 to 3 days, and satellite bulletins from SAB suggested that it
remained near tropical storm intensity during this period following
the issuance of JTWC's final warning. Incidentally, at 14/0230 UTC SAB's
Dvorak rating was T3.5--55 kts, implying a somewhat stronger storm than
analyzed by JTWC. Early on the 14th the IMD elevated the system to deep
depression status (i.e., 30 kts), but had downgraded it back to
depression status (25 kts) by 1200 UTC that day.
A graphic depicting the track of Tropical Cyclone 01A may be found at
the following link:
<http://www.tropicalcyclone2005.com/database/2006/NIO/BT-IMAGES/2006-01A.gif>
No damage or casualties are known to have resulted from Tropical
Cyclone 01A.
(Report written by Gary Padgett)
*************************************************************************
SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E
Activity for January: 1 tropical disturbance
1 intense tropical cyclone
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Southwest Indian Ocean tropical cyclones are the warnings issued by
the Tropical Cyclone Warning Centre on La Reunion Island, part of
Meteo France (MFR), and the Regional Specialised Meteorological Centre
for the basin. However, tropical cyclones in this region are named
by the Sub-regional Tropical Cyclone Advisory Centres in Mauritius and
Madagascar with longitude 55E being the demarcation line between their
respective areas of naming responsibility. The La Reunion centre only
advises these agencies regarding the intensity of tropical systems.
References to sustained winds imply a 10-minute averaging period unless
otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from MFR's coordinates by usually
40-50 nm or more. The JTWC warnings are also the source of the
1-minute average maximum sustained wind values included in the
tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Southwest Indian Ocean Tropical Activity for January
----------------------------------------------------
Whereas the eastern portion of the Southwest Indian Ocean basin had
been the scene of some tropical storm and cyclone activity during
November and December, in January the focus shifted to the western
portion of the basin, in particular the Mozambique Channel. Highlighting
the month of January was the extremely erratic Intense Tropical Cyclone
Boloetse late in the month and continuing into early February. A
detailed report on Boloetse follows.
Early in the month (3 January) another system formed in the Mozambique
Channel northwest of Europe Island, moved west-southwestward to the coast
of Mozambique, then sort of slid down the coastline, gradually working
its way farther inland. This system was designated as Tropical
Disturbance 07 by MFR, the highest 10-min avg sustained wind being
estimated at 25 kts, and this occurred while the center was just inland
from the Channel. JTWC's highest Dvorak rating was T2.0/2.0 at 0530 UTC
on 5 January, while SAB had assigned Dvorak numbers of T2.5/2.5 on the
4th while the center was still over water. The disturbance began to
drift farther inland on the 6th and had dissipated by the 7th.
A graphic depicting the track of this system may be found at the
following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-MFR07.gif>
INTENSE TROPICAL CYCLONE BOLOETSE
(MFR-08 / TC-09S)
24 January - 6 February
-----------------------------------------------------
Boloetse: contributed by Lesotho
A. Introduction and Storm Origins
---------------------------------
If a scale could be invented to quantify the "erratic-ness" of a
tropical cyclone's track, then surely Tropical Cyclone Boloetse would
rank in the Top Ten of all cyclones in all basins. This remarkable
cyclone existed in one form or another for almost two weeks in late
January and early February, and twice in its life became slow-moving
and erratic with a very convoluted track, in each case describing a
double loop. The first occasion occurred on 26-28 January while of
tropical storm intensity just east of southern Madagascar. The second
loop-de-loop happened from 31 January through 3 February in the south-
central Mozambique Channel, during which time Boloetse intensified from
a tropical depression into a tropical cyclone (i.e., hurricane).
After this point, however, the cyclone's track became very straight and
smooth, passing just off southwestern Madagascar as it sped southeast-
ward into the subtropical Southwest Indian Ocean.
A graphic (without date/time annotations) depicting the entire track
of Tropical Cyclone Boloetse may be found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-09S-BOLOESTE.gif>
John Diebolt has prepared three other graphics consisting of blowups
of certain portions of Boloetse's track. These will be referenced
below at appropriate points.
Boloetse's illustrious career began on 23 January when an area of
convection formed and persisted about 300 nm north-northwest of Reunion
Island. A 23/1128 UTC AMSU-B pass revealed that a LLCC was developing
near the convection. An upper-level analysis indicated that the system
was located within a low vertical shear environment with weak poleward
and equatorward divergence. RSMC La Reunion (MFR) initiated bulletins
on the developing LOW at 0000 UTC 24 January, numbering it as Tropical
Disturbance 08. The center of the system was located roughly 250 nm
north-northwest of Reunion Island. JTWC issued a TCFA for the system
at 24/2130 UTC--a 24/1918 UTC AMSU-B image had depicted an increase in
convection over a very small, but well-defined, LLCC. The developing
disturbance at the time was tracking west-southwestward in the general
direction of Madagascar.
B. Synoptic History: Phase I - East of Madagascar
-------------------------------------------------
Tropical Disturbance 08 continued to intensify and at 25/0000 UTC MFR
upgraded the system to tropical depression status with 30-kt winds. At
the same time, JTWC issued its first warning on TC-09S with the 1-min avg
MSW estimated at 35 kts. Six hours later MFR had further upgraded the
system to a moderate tropical storm with 40-kt winds (10-min avg). The
Meteorological Service of Madagascar concurred and assigned the official
name, Boloetse. At the time of its upgrade, Tropical Storm Boloetse was
located approximately 285 nm west-northwest of Reunion Island. The
newly-christened storm's track became more southerly as it tracked around
the western periphery of an anticyclone situated over the South Indian
Ocean. Boloetse reached an initial peak intensity of 50 kts at 0600 UTC
26 January with the CP estimated at 990 mb. Interestingly, while MFR
had upped the storm's MSW, JTWC lowered their MSW estimate from 45 kts
to 35 kts at 26/1200 UTC.
By this time the tropical storm was entering a region of ambiguous
steering between ridges to the east and west. The southerly motion
slowed and Boloetse reached the southernmost point of its track during
this phase of its life at 26/1800 UTC, being centered about 285 nm west-
southwest of Reunion Island. Also, the storm was showing signs of
weakening--at 1800 UTC MFR lowered the intensity to 40 kts. A ridge to
the southwest became the dominant steering influence and Boloetse
embarked on a somewhat "zig-zaggy" northwestward track, crossing its
earlier track once and almost reaching it again at 28/0000 UTC when
it jogged temporarily to the north-northeast. Unfavorable vertical
shear continued to increase and Boloetse was downgraded to a tropical
depression at 27/1800 UTC and further to tropical disturbance status
at 28/1200 UTC. After around 28/0000 UTC the system's track became
generally westerly and ex-Boloetse's center made landfall in eastern
Madagascar just north of Mananjary shortly before 29/0000 UTC with peak
winds estimated at only 25 kts. JTWC issued their final warning on the
system at 29/0000 UTC, but MFR continued to follow the weak system west-
ward across Madagascar. The MFR bulletin at 29/0000 UTC forecast
dissipation over the island, but just six hours later the next bulletin
suggested that ex-Boloetse would emerge into the Mozambique Channel with
a hint of some modest re-intensification.
A graphic depicting the track of Tropical Storm Boloetse up to and
including its Madagascar landfall may be found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-09S-BOLOESTE-A.gif>
C. Synoptic History: Phase II - Mozambique Channel
--------------------------------------------------
The weak remnant circulation of Boloetse moved westward across the
large island of Madagascar, turning to the northwest around 30/0000 UTC
and shortly afterward emerging into the Mozambique Channel just south
of Morandava. At this stage MFR was classifying ex-Boloetse as a "zone
of disturbed weather"--the weakest classification used by that agency.
Peak sustained winds were estimated at only 20 kts. After reaching
the Channel the disturbance moved somewhat to the north-northwest,
reaching a point approximately 250 nm west-southwest of Majunga around
30/1200 UTC. After this, the track bent to the southwest. The MFR
bulletin issued at 30/0600 UTC forecast the system to eventually regain
tropical storm status, and this is indeed what happened. JTWC issued
a TCFA at 30/2030 UTC, noting that the LLCC was improving in definition
and that convection was increasing in its vicinity. Shear was low to
moderate and upper-level outflow was good. MFR re-upgraded the system
to tropical depression status at 31/0600 UTC, and 12 hours later Tropical
Storm Boloetse had reformed about 200 nm east of Beira, Mozambique. At
the same time, JTWC re-initiated warnings on the storm, still designated
as TC-09S.
Once again Boloetse found itself in a weak steering environment. A
700-mb ridge to the southeast was the primary influence, but the ridge
was broad and weak. Over the next 1 & 1/2 days the tropical storm
drifted north-northwestward, described a tiny counter-clockwise loop,
moved slightly to the east, then generally southeastward. During the
time that Boloetse was trapped once again between two ridges,
environmental conditions were becoming quite favorable for
intensification: shear was low, SSTs were warm, and outflow was good.
Early on 2 February Boloetse began to strengthen rather rapidly--the MSW
was bumped up from 35 kts at 01/1800 UTC to 55 kts six hours later.
By 02/1200 UTC the storm had reached tropical cyclone (i.e., hurricane)
intensity while located only about 30 nm north of the point at which it
had been re-upgraded to tropical storm status two days earlier. By
0600 UTC 3 February a building ridge extending from an anticyclone east
of Madagascar was beginning to influence Boloetse and the cyclone had
begun to move on a definite southeasterly track. Intensification had
continued and winds were by this time up to 80 kts.
Tropical Cyclone Boloetse reached its peak intensity of 90 kts
(100 kts 1-min avg per JTWC) around 1800 UTC 3 February while centered
approximately 115 nm west-northwest of Toliara on the southwestern coast
of Madagascar, moving southeastward at 12 kts. The minimum CP estimated
by MFR was 946, and Boloetse at its peak remained a rather small tropical
cyclone. The radius of hurricane-force winds was around 30 nm, and gales
covered a zone about 180 nm in diameter. Based on MFR's warnings,
Boloetse retained its 'intense tropical cyclone' classification (MSW of
90 kts) for 18 hours before a slow weakening trend set in. The steady
southeasterly track continued, bringing the center of Boloetse to within
around 20-25 nm of the southwestern Madagascar coastline around 1200 UTC
4 February with the peak MSW estimated at 80 kts. Following the close
approach to Madagascar Boloetse's intensity began to decline more rapidly
due to the effects of land interaction and higher vertical shear.
The cyclone continued its southeasterly heading into the open South
Indian Ocean, gradually accelerating due to the effects of an approaching
mid-latitude trough. Boloetse was moving at around 11 kts when it made
its closest approach to Madagascar--24 hours later it was moving south-
eastward at 20 kts. After passing Madagascar the storm became
increasingly under the influence of the mid-latitude flow and gradually
began to lose its tropical characteristics. By 1800 UTC 5 February
the transition had progressed enough that MFR classified Boloetse as
an extratropical storm with winds estimated at 55 kts. The system
continued to speed southeastward to higher latitudes, and the final
MFR warning was issued at 06/1200 UTC, placing the center approximately
1000 nm to the south-southeast of Reunion Island.
A graphic depicting the convoluted track of Boloetse while in the
Mozambique Channel may be found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-09S-BOLOESTE-B.gif>
Another graphic depicting Boloetse's close approach to Madagascar and
its subsequent dash into mid-latitudes may be found at the following
link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-09S-BOLOESTE-C.gif>
D. Damage and Casualties
------------------------
While it is likely that gale-force winds, even gusts exceeding
hurricane force, along with torrential rainfall, would have been
experienced in southwestern Madagascar during the close approach of
Tropical Cyclone Boloetse, no reports of any damage or casualties
resulting from this tropical cyclone have been received.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for January: 2 severe tropical cyclones
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.
SEVERE TROPICAL CYCLONE CLARE
(TC-05S)
7 - 10 January
-------------------------------------------------
A. Introduction and Storm Origins
---------------------------------
Severe Tropical Cyclone Clare was the second tropical cyclone of the
2005-2006 season to form in the Perth TCWC's AOR and the first to make
landfall on the Australian continent. Earlier, in mid-November, Severe
Tropical Cyclone Bertie had formed at a very low latitude in the western
part of the Australian Region and subsequently moved west of longitude
90E into the Southwest Indian Ocean basin where it had been renamed
Alvin. Clare's story began with a weak LOW which on 4 January was
located in the Arafura Sea north of Cape Wessel but was expected to
move slowly westward. By the 6th the LOW was situated in the Timor Sea
near Bathhurst Island and the potential for development was considered
'high' for the 9th. However, things began happening faster than
expected.
Early on 7 January the LOW began to show signs of developing and Perth
initiated shipping warnings and tropical cyclone advices at 0600 UTC,
placing the center about 300 nm north-northeast of Broome and moving
west-southwestward at 14 kts. Steady intensification continued and
only six hours later Tropical Cyclone Clare was christened with winds
estimated up to 40 kts. Clare's center was then located about 230 nm
north of Broome, still moving west-southwestward at 14 kts. The rather
rapid development seen earlier did not continue, however, as an upper-
level anticyclone located to the south over the Kimberley region tended
to limit poleward divergence, although it was at the same time providing
good westward divergence.
B. Synoptic History
-------------------
By 0000 UTC 8 January Tropical Cyclone Clare's intensity began to
increase steadily. The MSW was upped to 50 kts at that time, and
15 hours later the system had reached severe tropical cyclone status
(i.e., hurricane intensity). At the time, Clare's center was located
approximately 145 nm north of Port Hedland, moving southwestward at
11 kts as it tracked around the northwestern periphery of a mid-level
ridge center over the Australian continent. By 0000 UTC 9 January
Severe Tropical Cyclone Clare reached its estimated peak intensity of
75 kts, which it maintained until after landfall. The minimum CP
estimated by BoM Perth was 960 hPa.
As Clare approached the coast its track became increasingly south-
southwesterly. The center of the severe tropical cyclone crossed the
Pilbara coast just to the west of Dampier around 09/1600 UTC, or midnight
local time. The MSW was estimated at 75 kts with peak gusts to 105 kts
as Clare moved onshore. Following landfall the cyclone began to weaken
quickly as it continued moving farther inland into the western portion
of the state of Western Australia. The final advice issued by BoM
Perth at 1500 UTC 10 January placed the center of the former tropical
cyclone about 190 km north-northeast of Gascoyne Junction, or about
110 km northwest of Mount Augustus.
The staff of the Perth TCWC has prepared an excellent online report
on Severe Tropical Cyclone Clare which may be accessed at the following
link:
<http://www.bom.gov.au/weather/wa/cyclone/clare/index.shtml>
Some of the information in this write-up has been taken from the BoM
report.
A graphic depicting the track of Severe Tropical Cyclone Clare may be
found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-05S-CLARE.gif>
C. Meteorological Observations
------------------------------
Following are some preliminary observations gleaned from the BoM
report on Clare:
Daily Rainfall (exact times not given)
======================================
Wickham 215 mm
Karratha 212 mm
Roebourne 205 mm
Maximum Winds
=============
Gust of 77 kts (142 km/hr) at Karratha at 09/1150 and 09/1450 UTC
Gust of 71 kts (131 km/hr) at Roebourne at 09/1240 UTC
Sustained wind (10-min avg) of 71 kts (131 km/hr) at Legendre Island
at 09/1000 UTC
D. Damage and Casualties
------------------------
Preliminary reports indicate that communities in Clare's path escaped
major structural damage although there were many reports of minor damage.
Downed power lines and flooding disrupted power and telecommunications to
many parts of the Pilbara region. The storm surge peaked as the tide was
approaching low tide, thus minimizing the effects of the surge. There
have been no reports of any storm surge damage. Also, fortunately no
fatalities or injuries have been reported.
E. Additional Discussion
------------------------
Clare was unusual for a cyclone of its intensity in that JTWC's 1-min
avg MSW estimates consistently ran well under BoM Perth's reported MSW
values. JTWC's peak MSW was 60 kts (1-min avg) at 09/0000 UTC, well
under the concurrent intensity from Perth of 75 kts--roughly equivalent
to a 1-min avg MSW of 85 kts. Surface observations, especially the
Legendre Island report of peak 10-min avg winds of 71 kts, support the
intensity reported by Perth. Clare appears to have been a case where
the appearance in satellite imagery did not reflect the true intensity
very well. I saved several satellite bulletins from JTWC and SAB, and
the highest Dvorak rating from both agencies was T3.5/3.5--55 kts for
a 1-min avg.
Which brings up another issue. The Perth TCWC's decision to upgrade
the tropical LOW to Tropical Cyclone Clare, as well as some of the
intensity estimates later in the cyclone's lifetime, were based in part
upon surface observations from offshore oil platforms. BoM has access
to this data because of contracts from the oil companies since the agency
provides additional warning services that are in excess of "normal"
community requirements. The data is considered proprietary since the
individual oil companies do not wish to make the data available to their
competitors; hence, it is not allowed to go into the WMO data system.
(The information in the above paragraph was based upon some information
received from Bruce Harper. My inclusion of this information should in
no wise be construed to the effect that I am either in agreement with
or critical of the oil companies' policy of keeping their data
proprietary.)
(Report by Gary Padgett)
SEVERE TROPICAL CYCLONE DARYL
(TC-08S)
17 - 23 January
-------------------------------------------------
A. Introduction and Storm Origins
---------------------------------
Following about 10 days after Clare, Severe Tropical Cyclone Daryl
formed near the Western Australian coastline and kept coastal residents
on alert for several days as it pursued a west-southwesterly track
parallel to the coastline, but fortunately the cyclone remained off-
shore and eventually dissipated at sea without moving inland. It did,
however, reach hurricane intensity as it chugged along on its cruise
down the coast. Like many Timor Sea tropical cyclones, Daryl had its
origins inland over northern Australia. As early as 14 January a
1001-mb tropical LOW, embedded in the monsoon trough, lay inland just
west of Borroloola. Over the succeeding days the LOW moved slowly
westward and by the 16th was near the Western Australia/Northern
Territory border. Recognizing the potential for tropical cyclone
development once the system moved out over the Timor Sea, the Perth
TCWC began issuing tropical cyclone advices at 0400 UTC on 17 January.
The poorly-defined center of the LOW was then located approximately
200 km south-southwest of Kalumburu and was essentially stationary.
The tropical LOW continued to drift westward and shipping bulletins
were initiated at 18/0600 UTC with the LOW located near Kuri Bay on the
west Kimberley coast. With the center of the LOW located over water
intensification proceeded quickly. Tropical Cyclone Daryl was named
at 18/1200 UTC, centered approximately 115 nm north-northeast of Broome
and moving west-southwestward at 5 kts with 35-kt winds.
B. Synoptic History
-------------------
At 1800 UTC 18 January the center of Daryl was relocated to a point
about 40 nm north-northwest of Cape Leveque. The MSW was upped to
40 kts, in part due to a report of 43 kts from Adele Island, located
approximately 40 nm to the north of the center. JTWC issued a TCFA
for Daryl at 2000 UTC. The remarks in the warning referenced the Adele
Island report, yet the agency did not issue their first warning until
19/0000 UTC, at which time Perth had raised the MSW to 50 kts (10-min
avg). Daryl at this time was centered about 115 nm north-northeast of
Broome and was moving southwestward at about 5 kts as it was guided
along the northwestern periphery of a mid-level ridge centered over
Australia. Daryl's intensity remained fairly constant for the next
couple of days as it moved in a west-southwesterly direction parallel
to the Western Australian coastline.
A 19/1701 UTC TRMM pass had indicated the presence of a developing
eye, and JTWC upped the MSW to 65 kts (1-min avg) at 20/0600 UTC.
Perth's intensity had been temporarily upped to 60 kts (10-min avg) at
20/0000 UTC, but this was dropped back to 50 kts at 20/0600 UTC. Daryl
was located within an environment of fairly strong easterly shear which
kept much of the deep convection pushed to the west of the partially-
exposed LLCC. Convection increased on the 20th in the western and
northern quadrants of Daryl due to a small upper-level anticyclone
which became superimposed on the tropical cyclone, helping to
ameliorate somewhat the effects of the moderate to high vertical shear.
BoM Perth upgraded Daryl to severe tropical cyclone (i.e., hurricane)
status with 65-kt winds at 1800 UTC, locating the center approximately
115 nm north-northeast of Karratha. Daryl was then moving west-
southwestward at 14 kts with the minimum CP estimated at 965 hPa.
The cyclone did not remain at hurricane intensity for very long--at
21/0300 UTC Perth lowered the MSW back to 55 kts. Satellite and radar
imagery indicated that deep convection had decreased during the past
few hours. As the 21st progressed convection continued to wane and
the upper and lower-level circulations began to decouple. Accordingly,
the warnings from both Perth and JWTC showed a decline in the intensity
as Daryl continued to move west-southwestward parallel to the coastline.
By 22/1200 UTC the LLCC was fully-exposed with cycling deep convection
located along the western periphery of the system. JTWC issued their
final warning on Daryl at this time. The Perth TCWC continued to main-
tain Daryl as a 40-kt tropical cyclone for another 18 hours. The final
gale warning from Perth was issued at 0600 UTC 23 January, placing the
center approximately 225 nm west-northwest of Carnarvon. Maximum winds
had decreased to 30 kts and the ex-Daryl LOW was moving southwestward
at 15 kts and expected to dissipate.
On 20 January some very cold cloud tops were noted in infrared
satellite imagery in association with Tropical Cyclone Daryl, the
coldest being -102.1 Deg C. The very cold tops colder than -100 Deg C
persisted for several hours, suggesting that they were not isolated
overshooting tops, but rather something of a more continuous nature with
a very cold local tropopause.
A graphic depicting the track of Severe Tropical Cyclone Daryl may be
found at the following link:
<http://www.tropicalcyclone2005.com/database/2006/SOHEM/BT-IMAGES/2006-08S-DARYL.gif>
C. Damage and Casualties
------------------------
Although Tropical Cyclone Daryl moved fairly close to the Western
Australian coastline and some areas may have experienced gale-force
or near gale-force gusts, no reports of significant damage nor any
casualties have been received.
(Report written by Gary Padgett)
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for January: 1 severe tropical cyclone
1 over land monsoon LOW
NOTE!!! - The Northeast Australia/Coral Sea basin will be covered in
the second installment of the January summary.
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for January: 3 tropical depressions
1 tropical cyclone of gale intensity
1 tropical cyclone of storm intensity
1 tropical cyclone of hurricane intensity **
** - system formed in Bribane's AOR and entered Fiji's AOR already at
hurricane strength
NOTE!!! - The South Pacific basin will be covered in the second
installment of the January summary.
*************************************************************************
SPECIAL FEATURE - SOURCES OF TROPICAL CYCLONE INFORMATION
The purpose of this section is to list some websites where many and
varied types of tropical cyclone information are archived. Many readers
will know about these already, but for the benefit of those who don't,
I wanted to include them.
(1) Aircraft Reconnaissance Information
---------------------------------------
Various types of messages from reconnaissance aircraft may be
retrieved from the following FTP site:
<ftp://ftp.nhc.noaa.gov/pub/products/nhc/recon/>
Information regarding how to interpret the coded reconnaissance
messages may be found at the following URL:
<http://www.nhc.noaa.gov/reconlist.shtml>
Links are also included to websites with further information about the
U. S. Air Force 53rd Weather Reconnaissance Squadron and the NOAA Air-
craft Operations Center.
(2) Archived Advisories
-----------------------
All the advisory products (public advisories, forecast/advisories,
strike probabilities, discussions, various graphics) issued by TPC/NHC
are archived on TPC's website. For the current year (using 2004 as an
example), the archived products can be found at:
<http://www.nhc.noaa.gov/archive/2004/index.shtml>
Links to tropical products archives for earlier years are available at
the following URL:
<http://www.nhc.noaa.gov/pastall.shtml>
JTWC warnings for past storms are archived on the NRL Monterry website:
<http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen.
I am not aware at the moment of any other TCWC which archives all
its tropical cyclone warning/advisory products for public access, but
if I learn of any, I will add them to this list.
(3) Satellite Imagery
---------------------
Satellite images of tropical cyclones in various sensor bands are
available on the NRL Monterrey and University of Wisconsin websites,
courtesy of Jeff Hawkins and Chris Velden and their associates. The
links are:
<http://www.nrlmry.navy.mil/tc_pages/tc_home.html>
<http://cimss.ssec.wisc.edu/tropic/tropic.html>
On the NRL site, the link to past years can be found in the upper left
corner of the screen. For the CIMSS site, a link to data archives is
located in the lower left portion of the screen.
Additional tropical satellite imagery, along with looping ability for
composite microwave imagery for the Western Hemisphere north of the
equator, can be found at:
(1) For the Eastern North Pacific:
<http://www.ssd.noaa.gov/PS/TROP/trop-epac.html>
(2) For the Atlantic, Gulf of Mexico and Caribbean Sea:
<http://www.ssd.noaa.gov/PS/TROP/trop-atl.html>
I'm sure there are other sites with available imagery available, and
as I learn of them, I will add the links to this list.
*************************************************************************
EXTRA FEATURE
In order to shorten the amount of typing in preparing the narrative
material, I have been in the habit of freely using abbreviations and
acronyms. I have tried to define most of these with the first usage
in a given summary, but I may have missed one now and then. Most of
these are probably understood by a majority of readers but perhaps a
few aren't clear to some. To remedy this I developed a Glossary of
Abbreviations and Acronyms which I first included in the August, 1998
summary. I don't normally include the Glossary in most months in
order to help keep them from being too long. If anyone would like to
receive a copy of the Glossary, please e-mail me and I'll be happy
to send them a copy.
*************************************************************************
AUTHOR'S NOTE: This summary should be considered a very preliminary
overview of the tropical cyclones that occur in each month. The cyclone
tracks (provided separately) will generally be based upon operational
warnings issued by the various tropical cyclone warning centers. The
information contained therein may differ somewhat from the tracking and
intensity information obtained from a "best-track" file which is based
on a detailed post-seasonal analysis of all available data. Information
on where to find official "best-track" files from the various warning
centers will be passed along from time to time.
The track files are not being sent via e-mail. They can be retrieved
from the archive sites listed below. (Note: I do have a limited e-mail
distribution list for the track files. If anyone wishes to receive
these via e-mail, please send me a message.)
Both the summaries and the track files are standard text files
created in DOS editor. Download to disk and use a viewer such as
Notepad or DOS editor to view the files.
The first summary in this series covered the month of October,
1997. Back issues can be obtained from the following websites
(courtesy of Michael Bath, Michael V. Padua, Michael Pitt, Chris
Landsea, and John Diebolt):
<http://australiasevereweather.com/cyclones/>
<http://www.typhoon2000.ph>
<http://mpittweather.com>
<ftp://ftp.aoml.noaa.gov/hrd/pub/landsea/padgett/>
<http://www.tropicalcyclone2005.com/>
Another website where much information about tropical cyclones may
be found is the website for the UK Meteorological Office. Their site
contains a lot of statistical information about tropical cyclones
globally on a monthly basis. The URL is:
<http://www.metoffice.gov.uk/weather/tropicalcyclone>
TROPICAL CYCLONE REPORTS AVAILABLE
JTWC now has available on its website the Annual Tropical Cyclone
Report (ATCR) for 2004 (2003-2004 season for the Southern Hemisphere).
ATCRs for earlier years are available also.
The URL is: <http://199.10.200.33/jtwc.html>
Also, TPC/NHC has available on its webpage nice "technicolor"
tracking charts for the 2004 Atlantic and Eastern North Pacific
tropical cyclones; also, storm reports for all the 2004 Atlantic
and Eastern North Pacific cyclones are now available, as well as
track charts and reports on storms from earlier years.
The URL is: <http://www.nhc.noaa.gov>
A special thanks to Michael Bath of McLeans Ridges, New South Wales,
Australia, for assisting me with proofreading the summaries.
PREPARED BY
Gary Padgett
E-mail: garyp@alaweb.com
Phone: 334-222-5327
Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South
China Sea)
E-mail: newchapelobservatory@btinternet.com
Simon Clarke (Northeast Australia/Coral Sea, South Pacific)
E-mail: saclarke@iprimus.com.au
*************************************************************************
*************************************************************************
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