MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
FEBRUARY, 2007
(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 FROM THE AUTHOR - PLEASE READ **********
The tropical cyclone reports for the Southwest Indian Ocean basin this
month have a new look. The idea of following a structured template to
present basic information was suggested by Matthew Saxby of Queanbeyan,
New South Wales. I have taken Matthew's idea, modified it some, and sent
it around to several persons to be vetted. The response I've received to
this new format has been very favorable. Barring some unforeseen
complication, beginning with the March, 2007, edition, all the tropical
cyclone reports will be constructed in this new format.
As can be seen from the Southwest Indian cyclone reports below, the
new format is as follows:
(1) Section A - General Information
This section will contain salient information about the cyclone in
a very structured format, allowing for quick comparison between
cyclones. Dates and intensities are based upon the operational
tracks prepared by the author.
(2) Section B - Synoptic History
This section will contain a narrative description of the origin of
the cyclone and a general description of its track history. To
realize the full benefit of the summaries, readers should use this
section in conjunction with the tabular tracks prepared by the
author and the track graphic maps prepared by John Diebolt. (The
Wikipedia reports also contain non-annotated track graphics.) In
order for me to keep producing the summaries and to expedite the
production time required, the track description will not be as
detailed as in the past. There will be no attempt to describe every
twist and turn of the track or every 5 or 10-kt fluctuation in
intensity.
(3) Section C - Meteorological Data
This section will be pretty much as before, reporting on all the
significant observations I have available (and occasionally some
not-so-significant ones).
(4) Section D - Damage and Casualties
This section will contain the same level of detail as before,
relying heavily on links and the online Wikipedia reports.
(5) Section E - Additional Discussion
This section will contain any additional discussion related to
differing intensity estimates, or any other items deemed to be of
general interest.
SPECIAL NOTE #2: Very happily, John Diebolt of Tucson, Arizona, now has
his tropical cyclone website up and running again and has begun once more
to produce graphic images depicting the tracks of all tropical systems
for which I prepare a tabular track in the companion cyclone tracks file.
These can be accessed at the following URL:
http://www.tropicalcyclone2005
Scroll down the chart to the month of interest and click on the green
bar under "Operational Track Image" for the desired system.
The tabular track of positions and intensities may also be obtained
from the above website, or from the other archival sites listed in
the Author's Note in the closing section of this summary.
SPECIAL NOTE #3: Short reports with satellite pictures and small-scale
maps for all the Southern Hemisphere systems may be found at the
following link:
http://en.wikipedia.org/wiki
******************************
FEBRUARY HIGHLIGHTS
--> Significant tropical cyclone outbreak in Southwest Indian Ocean
--> Gulf of Carpentaria cyclone affects northeastern Australia
******************************
!!!!!!!!!! EXTRA FEATURE !!!!!!!!!!
2007 TROPICAL CYCLONE NAMES
TROPICAL CYCLONE NAMES for the NORTHWEST PACIFIC BASIN
Beginning in 2000 tropical storms and typhoons forming in the North
Pacific west of the Dateline are assigned names by JMA taken from a
new list of Asian names contributed by fourteen nations and territories
from the western Pacific and eastern Asia. Names are not allocated
in alphabetical order and the majority are not personal names--instead
names of animals, plants, fictional characters, descriptive adjectives,
places--even foods--are utilized. The entire list consists of 140
names and all names will be used before any are repeated. The last
name assigned in 2006 was Trami in December. As of 28 March no
tropical cyclones have been named in 2007.
The next 36 names on the list are (** indicates name has already
been assigned in 2007):
Kong-rey Danas Kajiki Halong
Yutu Nari Faxai Nakri
Toraji Wipha Peipah Fengshen
Man-yi Francisco Tapah Kalmaegi
Usagi Lekima Mitag Fung-wong
Pabuk Krosa Hagibis Kammuri
Wutip Haiyan Noguri Phanfone
Sepat Podul Rammasun Vongfong
Fitow Lingling Matmo Nuri
Since 1963 PAGASA has independently named tropical cyclones forming
in the Philippines' AOR--from 115E to 135E and from 5N to 25N (except
for a portion of the northwestern corner of the above region). Even
though the Philippines contributed ten names to the international list
of typhoon names, PAGASA still continues to assign their own names for
local use within the Philippines. It is felt that familiar names are
more easily remembered in the rural areas and that having a PAGASA-
assigned name helps to underscore the fact that the cyclone is within
PAGASA's AOR and potentially a threat to the Philippines. Another
consideration may be PAGASA's desire to assign a name when a system is
first classified as a tropical depression. Since tropical and/or
monsoon depressions can bring very heavy rainfall to the nation which
often results in disastrous flooding, the weather service feels that
assigning a name helps to enhance public attention given to a system.
Beginning with 2001 PAGASA began using new sets of cyclone names.
These do not all end in "ng" as did the older names. Four sets of 25
names will be rotated annually; thus, the set for 2007 will be re-used
in 2011. In case more than 25 systems are named in one season, an
auxiliary set will be used. PAGASA names for 2007 are (** indicates
name has already been assigned in 2007):
Amang Juaning Ramon
Bebeng Kabayan Sendong
Chedeng Lando Tisoy
Dodong Mina Ursula
Egay Nonoy Viring
Falcon Onyok Weng
Goring Pedring Yoyoy
Hanna Quiel Zigzag
Ineng
In the unlikely event that the list is exhausted, the following
names would be allocated as needed: Abe, Berto, Charo, Dado, Estoy,
Felion, Gening, Herman, Irma, and Jaime.
NORTH INDIAN OCEAN CYCLONE NAMES
After several years of planning and working out implementation
details, the RSMC for the North Indian Ocean basin--the Indian
Meteorological Department--began naming tropical cyclones in that
region on an experimental basis in the autumn of 2004.
The procedure for allocating names is similar to that used in the
Northwest Pacific basin. All the member nations--eight in this case--
submitted eight names each. The 64 names were arranged in eight
columns of eight names, ordered by the contributing nations in alpha-
betical order, just as is done in the Northwest Pacific. Potential
cyclonic storms for 2007 include (** indicates name has already been
assigned):
Akash Nargis Bijli
Gonu Abe Aila
Yemyin Khai Muk Phyan
Sidr Nisha Ward
******************************
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: No tropical cyclones
******************************
NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180
Activity for February: No tropical cyclones
******************************
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 severe tropical storm
1 tropical cyclone
3 intense tropical cyclones **
** - one of these formed late in January and continued to near the
middle of February
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 February
------------------------------
As the month of February opened, Intense Tropical Cyclone Dora was
slowly gathering strength as it pursued a south-southwesterly track
which carried it near Rodrigues Island and then well to the east of
Mauritius and La Reunion. Dora peaked at 100 kts on the 3rd while
northeast of Rodrigues and was the second cyclone of the 2006-2007
season to reach the intense tropical cyclone threshold of 90 kts.
The complete report on Dora may be found in the January summary.
Dora heralded a rather remarkable outbreak of tropical cyclone
activity in the Southwest Indian basin. During the month four named
tropical storms developed with all but one reaching tropical cyclone
status. Indeed, Severe Tropical Storm Enok came very close to reaching
hurricane intensity, and may have actually done so, at least in terms
of a 1-min avg MSW. Intense Tropical Cyclone Favio followed a long
trajectory from west of Diego Garcia southwestward to just south of
Madagascar, thence curving to the west-northwest and striking the
nation of Mozambique as an intense tropical cyclone. The long-lived
Gamede, also another intense tropical cyclone, moved along a long path
from well to the southeast of Diego Garcia to a point off the north-
eastern coast of Madagascar. From there it made a sharp bend to the
south and subsequently tracked southward roughly parallel to the east
coast of the big island. Finally, Tropical Cyclone Humba, which actually
formed in Perth's AOR, followed a southerly track through the eastern
portion of the basin. Reports on all four named storms follow.
SEVERE TROPICAL STORM ENOK
(MFR-08 / TC-13S)
6 - 11 February
------------------------------
A. General Information
----------------------
1. Identification
a. RSMC - Meteo France La Reunion (MFR)
b. MFR - Tropical Disturbance 08
c. JTWC - Tropical Cyclone 13S
d. NAME - Enok (named by Mauritius at Feb 09/1200 UTC; name
contributed to the regional list by Namibia)
2. Overview
a. Basins Affected: Southwest Indian Ocean (SWI)
b. Dates: 6 - 11 February, 2007
c. Max Sust Winds: 60 kts (10-min avg per MFR)
55 kts (1-min avg per JTWC) (See Section D)
d. Min Cent Press: 980 hPa (estimate per MFR)
3. Beginning of Track: Feb 06/0000 UTC, near 18.6S/50.9E, or about
200 nm east of Antananarivo, Madagascar, as referenced in a JTWC
satellite bulletin.
4. Peak Intensity: Feb 10/1000 UTC, near 15.8S/58.8E, or about 275 nm
north-northeast of Mauritius, or very near Ile Saint-Brandon.
5. Size: At its peak Tropical Storm Enok was a rather compact storm
with the maximum gale radius being on the order of around 50-70 nm.
6. End of Track: Feb 11/1800 UTC, near 23.4S/64.6E, or about 250 nm
south-southeast of Rodrigues Island.
B. Synoptic History
-------------------
1. Origin: The earliest known (to the author) reference to the
pre-Enok system was a satellite bulletin issued by JTWC at 0000 UTC
on 6 February. The system must have developed fairly rapidly--at
06/1000 UTC a TCFA was issued by the same agency as a area of deep
convection was persisting over a well-defined LLCC in the presence
of low vertical shear and with excellent equatorward and poleward
outflow channels being provided by an upper-level anticyclone.
2. General Description of Track: System formed just east of northern
Madagascar, moved northward parallel to coast during its formative
stages, then began to move east-northeastward and eventually eastward
as it developed. After reaching tropical storm status, Enok began to
accelerate east-southeastward and ultimately south-southeastward as
it weakened. Around 0300 UTC 10 February Enok's center passed only
about 8 nm to the northeast of tiny Saint-Brandon Island, and at
1800 UTC passed to within 25 nm north-northeast of Rodrigues Island.
The primary factor contributing to the storm's somewhat unusual track
was the strong gradient flow between a near-equatorial ridge to the
northeast and troughing extending northwestward from the remnants of
Tropical Cyclone Dora to the south. Enok was already weakening as
it passed near Rodrigues and subsequently weakened rapidly due to the
effects of increased vertical shear and advection of dry, stable mid-
tropospheric air.
C. Meteorological Data
----------------------
Karl Hoarau has sent me some observations recorded on the small island
of Saint-Brandon (WMO 61986, 16.5S/59.6E, Elev 3 m above MSL).
At 10/0100 UTC the station recorded 10-min avg winds of 44 kts with
a SLP of 988 hPa. At 0200 UTC the 10-min avg wind was still 44 kts with
a SLP of 982 hPa. At the latter hour the center of Enok was located
about 8 nm northeast of the island. Between 0200 and 0300 UTC, the SLP
rose 16 hPa to 998 hPa. The peak gust recorded on the island (exact
time unknown) was 87.5 kts.
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Storm Enok
have been received.
E. Additional Discussion
------------------------
According to the track file prepared by the author, based primarily
upon the warnings received from RSMC La Reunion (MFR), Enok was upgraded
from a 30-kt tropical depression to a 50-kt severe tropical storm at
1800 UTC 9 February. However, the system was actually named by the
Sub-Regional Tropical Cyclone Advisory Centre in Mauritius at 1200 UTC.
Dvorak classifications from AFWA and JTWC at this time were T3.0/3.0,
but were still T2.5/2.5 from MFR and SAB. However, the storm during
this time was intensifying rather rapidly, and by 1800 UTC MFR's rating
had jumped to T3.5/3.5.
Karl Hoarau has also provided an analysis of Enok's intensity. Karl
feels that the system had reached tropical storm intensity (1-min avg
basis) by 09/0600 UTC and hurricane intensity (1-min avg basis) at
09/2100 UTC. A microwave image of Enok as early at 09/1611 UTC reveals
an eye-like feature, and the 87.5-kt gust recorded on the island suggests
a 1-min avg MSW of 70 kts, or a 10-min avg wind of 62 kts. In Karl's
opinion Enok likely reached a peak of 75-kts (1-min avg) around 0300 UTC
on 10 February before beginning to weaken.
Following are the MSW (1-min avg) estimates sent by Dr. Hoarau:
Feb 09-0600 UTC: 35 kts
Feb 09-0900 UTC: 35 kts
Feb 09-1200 UTC: 45 kts
Feb 09-1500 UTC: 50 kts
Feb 09-1800 UTC: 60 kts
Feb 09-2100 UTC: 65 kts
Feb 10-0000 UTC: 70 kts
Feb 10-0300 UTC: 75 kts
Feb 10-0600 UTC: 70 kts
(Report written by Gary Padgett)
INTENSE TROPICAL CYCLONE FAVIO
(MFR-09 / TC 14S)
12 - 23 February
------------------------------
A. General Information
----------------------
1. Identification
a. RSMC - Meteo France La Reunion (MFR)
b. MFR - Tropical Disturbance 09
c. JTWC - Tropical Cyclone 14S
d. NAME - Favio (named by Mauritius at Feb 15/0600 UTC; name
contributed to the regional list by the Seychelles)
2. Overview
a. Basins Affected: Southwest Indian Ocean (SWI)
b. Dates: 12 - 23 February, 2007
c. Max Sust Winds: 100 kts (10-min avg per MFR)
125 kts (1-min avg per JTWC)
d. Min Cent Press: 930 hPa (estimate per MFR)
3. Beginning of Track: Feb 12/0000 UTC, near 10.3S/70.0E, or about
225 nm southwest of Diego Garcia, as referenced in initial bulletin
issued by MFR.
4. Peak Intensity: Feb 21/0000 UTC, near 24.5S/39.9E, or about 400 nm
southeast of Beira, Mozambique. (It should be noted that MFR's MSW
was at 100 kts from 20/1200 through 21/1200 UTC.)
5. Size: At its peak Tropical Cyclone Favio was an intense but fairly
small system with the maximum gale radius being on the order of
70-90 nm.
6. End of Track: Feb 23/1200 UTC, near 19.1S/32.6E, or inland about
250 km west-northwest of Beira over western Mozambique.
B. Synoptic History
-------------------
1. Origin: The earliest known (to the author) reference to the pre-Favio
system was the first bulletin issued by MFR at 0000 UTC 12 February.
Unfortunately, I do not have available the STWO issued by JTWC for
that date. The STWO for 13 February noted that an area of convection
was located approximately 295 nm south-southwest of Diego Garcia.
Convection was flaring over a consolidating LLCC in the presence of
favorable outflow and low vertical shear. Deep convective bursts
continued as the environment improved and a TCFA was issued at 2100
UTC followed by JTWC's first warning at 1200 UTC 14 February.
However, another 18 hours elapsed before the system was named Favio
by the Meteorological Services of Mauritius.
2. General Description of Track: Favio's track was long and rather
unusual, being (as far as can be discerned right now), the first
known tropical cyclone to move westward south of the island of
Madagascar and strike the African mainland as an intense tropical
cyclone. From its origin on the 12th a few hundred miles to the
southwest of Diego Garcia, Favio moved on a remarkably steady
southwesterly track which took it less than a hundred miles north
of Rodrigues Island on the 15th and then a few hundred miles east
of the Mascarenes on the 16th as it was steered by a large subtropical
ridge to the southeast.
The ridge began to build westward, eventually merging with a ridge
anchored over South Africa. The tropical storm obligingly turned
to a westerly track and passed less than a hundred miles south of
the southern tip of Madagascar on the 19th. After Favio had entered
the Mozambique Channel and begun to strengthen, the African ridge
became the dominant steering mechanism and guided the cyclone on
a west-northwesterly course which took it inland on the southern
Mozambique coast on 22 February.
C. Meteorological Data
----------------------
1. Rodrigues Island: The center of (then) Tropical Storm Favio passed
about 80 nm west of the island on 15 February. Station FIMR/619880
(19.67S/63.40E, 59.1 m above MSL) reported peak winds of ENE 32 kts,
gusting to 49 kts at 15/0900 UTC. A peak gust of 49 kts was also
reported at 1000 UTC.
2. The small, tight center of Tropical Cyclone Favio passed about 25 nm
south of buoy 56511 which reported a SLP of 974 hPa at 20/0100 UTC.
The buoy was likely on the northern edge of the northern eyewall,
which, if true, would suggest a CP of around 955 hPa at the time.
(The estimated MSW at the time was 80 kts.)
3. Landfall in Mozambique was very close to station FQVL which was
located in the northern eyewall. The station ceased reporting after
the pressure had fallen to 992 hPa, which was about two hours before
the center made its closest approach.
The above observations were sent to the author by Derrick Herndon. A
special thanks to Derrick for sending the information.
D. Damage and Casualties
------------------------
Striking Mozambique exactly seven years to the day after Eline, the
last intense tropical cyclone to strike the country, Favio left a trail
of destruction and compounded problems for the nation which was still
suffering the aftermath of flooding during the previous month that had
left 120,000 homeless. The cyclone initially struck the Bazaruto
Islands, noted for resorts. Favio made landfall near the resort city
of Vilanculos, destroying thousands of homes and damaging many other
public buildings, including hospitals, schools and a prison. Around
600 prisoners escaped when the jail was destroyed.
News reports indicate that four persons died in the cyclone with
scores injured. Electrical services were disrupted, and many roads
were blocked by fallen trees, hindering emergency vehicles from easily
reaching those needing help. Many fields full of crops such as cassava
and maize were washed away. It was feared that the rains attending
Favio would exacerbate the flooding which had caused much misery in
the country during the previous weeks.
(Report written by Gary Padgett)
INTENSE TROPICAL CYCLONE GAMEDE
(MFR-10 / TC-15S)
20 February - 4 March
------------------------------
A. General Information
----------------------
1. Identification
a. RSMC - Meteo France La Reunion (MFR)
b. MFR - Tropical Disturbance 10
c. JTWC - Tropical Cyclone 15S
d. NAME - Gamede (named by Mauritius at Feb 21/0600 UTC; name
contributed to the regional list by South Africa)
2. Overview
a. Basins Affected: Southwest Indian Ocean (SWI)
b. Dates: 20 February - 4 March, 2007
c. Max Sust Winds: 95 kts (10-min avg per MFR)
105 kts (1-min avg per JTWC)
d. Min Cent Press: 935 hPa (estimate per MFR)
3. Beginning of Track: Feb 20/1200 UTC, near 14.8S/74.8E, or about
475 nm south-southeast of Diego Garcia, as referenced in initial
bulletin issued by MFR.
4. Peak Intensity: Feb 25/1800 UTC, near 18.5S/53.9E, or about 225 nm
west-northwest of Mauritius. (It should be noted that MFR's MSW
was at 95 kts from 25/1800 through 26/1200 UTC.)
5. Size: At its peak Tropical Cyclone Gamede was a rather large tropical
cyclone with gales extending outward 150 nm from the center in all
directions and up to 250 nm in the southern semicircle.
6. End of Track: Mar 04/1200 UTC, near 32.4S/49.7E, or about 750 nm
south-southwest of Reunion Island.
B. Synoptic History
-------------------
1. Origin: Gamede's origin seems to lie in an area of convection which
developed on 19 February about 610 nm southeast of Diego Garcia. A
weak but well-defined LLCC was in evidence with some associated
convective banding north of the center and some deep convection
flaring over the center. By the 20th the system was situated beneath
an upper-level anticyclone which was providing low vertical shear and
favorable eastward and equatorward outflow. MFR initiated warnings
on the system and JTWC upped the development potential to 'fair'.
Convective organization continued to improve and JTWC issued a TCFA
at 20/2000 UTC, followed by the first warning at 21/0600 UTC. At
the same time, Mauritius and MFR upgraded the system to tropical storm
status with Mauritius assigning the name Gamede.
2. General Description of Track: During its early stages Gamede moved
initially westward, then west-southwestward as it was steered by a
strong mid-level subtropical ridge to the south. The cyclone had
become quasi-stationary by late on the 25th due to the competing
steering influences of the subtropical ridge anchored south of
Madagascar and a near-equatorial ridge to the east-northeast of the
storm. Gamede was at its peak intensity at this time, but began
to slowly weaken, in part due to a decrease in local SSTs brought
about by upwelling while the cyclone was essentially stationary.
By early on the 27th Gamede had embarked on a south-southwesterly
track as the near-equatorial ridge built southward and a mid-latitude
trough induced a weakness in the subtropical ridge.
The motion toward the south-southwest, roughly parallel to and about
200 nm east of the coastline of Madagascar, continued as Gamede
continued to slowly weaken. Shear began to increase on 1 March as
the system encountered stronger mid-latitude flow, and Gamede was
classified as an extratropical cyclone at 1200 UTC on 2 March. As
Gamede underwent extratropical transition, a subtropical ridge began
to build eastward from South Africa, causing the southerly motion
to slow and eventually come to a halt. MFR issued their final warning
at 04/1200 UTC with the gale quasi-stationary about 750 nm to the
south-southwest of Reunion Island.
C. Meteorological Data
----------------------
1. According to some information received from Derrick Herndon, Gamede
passed 50 nm north of buoy 14926 around 1200 UTC on 22 February.
The buoy reported a SLP of 985 hPa from a position estimated to be
a little south of the southern eyewall. This would suggest a CP of
around 970 hPa. Environmental pressures in the area were running
around 1008 hPa, resulting in a delta of 38 hPa--in good agreement
with latest AMSU estimates.
2. The eye of Gamede passed over Saint-Brandon Island around 1100 UTC
on 23 February with a minimum SLP of 960 hPa being recorded.
3. Philippe Caroff, Chief Forecaster at RSMC La Reunion, sent some data
describing record rainfall produced on the island by Gamede. The
cyclone's center never approached closer than 125 nm to the island,
but remained within 215 nm of Reunion for more than 90 hours. The
large extension of Gamede induced persistent heavy rainfall in the
mountains on the island. While peak rainfall intensities were never
extreme, accumulated totals were very impressive, exceeding 2500 mm
in four days.
Some world records fell. The 72-hour record rainfall of 3240 mm
established in January, 1980, during Tropical Cyclone Hyacinthe
was beaten twice with 3929 mm at Commerson's Crater (2286 metres
elevation) and with 3264 mm recorded at Hell Bourg (a village at
914 metres).
Other records for periods ranging up to 9 days were also beaten by
Commerson's Crater values:
4 days - 4869 mm
5 days - 4979 mm
6 days - 5075 mm
7 days - 5400 mm
8 days - 5510 mm
9 days - 5512 mm
In addition, the previous 4-day rainfall record at Hell Bourg of
3551 mm was eclipsed by a 96-hour total of 3633 mm associated with
Tropical Cyclone Gamede.
D. Damage and Casualties
------------------------
The heavy rains on Reunion Island led to some flood damage with one
woman being reported missing after her car was swept away by flood
waters. A bridge collapsed near the southern town of Saint-Louis with
the cost estimated at 20 million euros (US$26.32 million).
No other reports of damage or casualties associated with Intense
Tropical Cyclone Gamede have been received.
(Report written by Gary Padgett)
TROPICAL CYCLONE HUMBA
(MFR-11 / TC-16S)
20 - 28 February
------------------------------
A. General Information
----------------------
1. Identification
a. RSMC - BoM Perth/Meteo France La Reunion (MFR)
b. MFR - Tropical Disturbance 11 (West of 90E)
c. JTWC - Tropical Cyclone 16S
d. NAME - Humba (named by Mauritius at Feb 23/0600 UTC; name
contributed to the regional list by Tanzania)
2. Overview
a. Basins Affected: Northwest Australia/Southeast Indian Ocean (AUW)
Southwest Indian Ocean (SWI)
b. Dates: 20 - 28 February, 2007
c. Max Sust Winds: 75 kts (10-min avg per MFR)
70 kts (1-min avg per JTWC)
d. Min Cent Press: 960 hPa (estimate per MFR)
3. Beginning of Track: Feb 20/2100 UTC, near 10.0S/92.0E, or about
350 nm west-northwest of the Cocos Islands, as referenced in initial
gale warning issued by BoM Perth.
4. Peak Intensity: Feb 25/0600 UTC, near 19.6S/79.0E, or about 800 nm
south-southeast of Diego Garcia. (It should be noted that MFR's
MSW was at 75 kts from 25/0600 through 25/1800 UTC.)
5. Size: Based on MFR's warnings, at its peak Tropical Cyclone Humba
was a somewhat compact system with a gale radius of 60 nm. However,
JTWC's warnings described a somewhat larger cyclone with gale radii
in the various quadrants averaging slightly over 100 nm.
6. End of Track: Feb 28/1200 UTC, near 29.8S/78.3E, or about 1400 nm
south-southeast of Diego Garcia.
B. Synoptic History
-------------------
1. Origin: The daily Tropical Cyclone Outlook issued by BoM Perth on
19 February mentioned a tropical LOW which was located about 170 nm
northwest of the Cocos Islands. The development potential was rated
'high' over the next couple of days. A STWO issued by JTWC on the
20th noted that deep convection was flaring along a convergent band
on the southwestern periphery of a well-defined, though broad, LLCC.
Vertical shear in the region was low and an anticyclone aloft was
providing good outflow. The Perth TCWC began issuing gale warnings
at 20/2100 UTC in anticipation of the system strengthening further.
JTWC issued a TCFA at 21/0930 UTC due to the development of deep
convection near a well-defined LLCC. Outflow remained excellent
and shear was forecast to decrease as the disturbance continued
moving southward under a ridge axis.
At 21/1200 UTC JTWC issued the first warning on TC-16S, assessing
the MSW at 35 kts (1-min avg). At the same time the system crossed
longitude 90E and official warning responsibility was passed from
BoM Perth to RSMC La Reunion. Perth had been assessing the intensity
at 30 kts (10-min avg), but MFR lowered this to 25 kts in their
warnings, except for the possibility of 30 kts locally in the southern
semicircle. The MSW was upped to 30 kts at 22/0600 UTC, and at
23/0600 UTC the depression was officially upgraded to Tropical Storm
Humba, the name being assigned by the Meteorological Services of
Mauritius.
2. General Description of Track: Tropical Cyclone Humba for the most
part followed a rather smooth trajectory curving around the north-
western and later western periphery of a subtropical ridge anchored
over Western Australia. The storm was moving west-southwesterly on
the 21st as it entered the Southwest Indian Ocean basin, but the
motion became more toward the southwest on the 23rd, and by the time
of Humba's peak intensity on 25 February the cyclone was moving in
a south-southwesterly direction. Shortly after peaking in intensity
an upper-level trough began to overtake the system from the west,
increasing vertical shear and decreasing outflow aloft. The storm
began to steadily weaken and was declared extratropical at 0600 UTC
on 27 February. By the 28th the extratropical gale had slowed and
turned westward just north of latitude 30S due to a blocking HIGH
to the south, and MFR issued its final warning on the system at
1200 UTC.
C. Meteorological Data
----------------------
No meteorological observations have been received by the author in
association with Tropical Cyclone Humba.
D. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Cyclone
Humba have been received.
(Report written by Gary Padgett)
******************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for February: 2 tropical LOWs **
** - one system eventually became a tropical cyclone in the Southwest
Indian Ocean
Northwest Australia/Southeast Indian Ocean
Tropical Activity for February
------------------------------
No tropical cyclones traversed waters between 90E and 135E during the
month of February. A tropical LOW formed on 3 February about 310 nm
north of the Cocos Islands. The system was referenced in the daily
Tropical Cyclone Outlooks for the Central Indian Ocean issued by the
Perth TCWC from the 3rd through the 7th. The LOW meandered about in the
same general area for several days but never developed to the point that
gale warnings were required. The potential for development was rated
'high' on the 4th and 5th, but this had decreased by the 6th. No track
was included for this system in the companion cyclone tracks file.
Another tropical LOW developed well west of the Cocos Islands on the
20th with gale warnings being initiated. This LOW subsequently moved
west of 90E where it developed into Tropical Storm Humba on 23 February.
The report on Tropical Cyclone Humba may be found in the preceding
section of this summary covering the Southwest Indian Ocean.
******************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for February: 1 tropical cyclone of storm intensity
1 monsoon LOW of gale intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
Northeast Australia/Coral Sea tropical cyclones are the warnings
and advices issued by the Tropical Cyclone Warning Centres at
Brisbane, Queensland, and Darwin, Northern Territory, and on very
infrequent occasions, by the centre at Port Moresby, Papua New
Guinea. References to sustained winds imply a 10-minute averaging
period unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Australian centres' coor-
dinates by usually 40-50 nm or more. The JTWC warnings are also the
source of the 1-minute average maximum sustained wind values included
in the tracks file. Additionally, information describing details of
satellite imagery and atmospheric circulation features included in
the narratives is often gleaned from the JTWC warnings.
Northeast Australia/Coral Sea
Tropical Activity for February
------------------------------
A tropical LOW formed near the Top End of the Northern Territory at
the end of January and spent several days zigzagging around the Gulf of
Carpentaria. Finally, almost a week after its genesis, the LOW was able
to strengthen into a tropical cyclone in the southeastern Gulf and was
named Nelson. Nelson intensified quickly and became a Category 2 cyclone
on the Australian Scale shortly before landfall at the base of the Cape
York Peninsula. A report on Tropical Cyclone Nelson, authored by Simon
Clarke, follows.
The Brisbane TCWC issued gale warnings from 5 to 8 February on a
monsoon LOW which formed east of Cairns on the 5th and subsequently
moved southeastward parallel to the Queensland coastline. The LOW
weakened early on the 6th, but reformed to the west early on the 7th
less than 100 nm east of Cairns. This LOW helped to draw away most
of the moisture feeding into the weakening overland Nelson and led to
that system's quick decay following landfall. Gales of up to 40 kts
were forecast in association with the monsoon LOW, but the system did
not have the structure of a tropical cyclone; hence, no name was
assigned. A track was included for this system in the companion cyclone
tracks file and a track graphic can be found on John Diebolt's website.
TROPICAL CYCLONE NELSON
(TC-12P)
31 January - 7 February
------------------------------
A. Storm Origins
----------------
The tropical LOW that was to eventually become Tropical Cyclone
Nelson developed to the north of Melville Island, Northern Territory,
as early as 30 January. The LOW formed at the western end of a
re-invigorated monsoon trough, which linked to another developing
tropical LOW in the far northwestern Coral Sea. This other tropical
LOW moved overland into the Palmerville-Georgetown region of
Queensland over the next few days and was responsible for directing a
significant moisture-laden air mass onto Queensland’s tropical east
coast that produced torrential rains and flooding for several days
between Innisfail and Sarina. The BoM reported that several records
were broken. Warden Bend recorded a new extreme daily total of
268.6 mm, while Hecate with 349.2 mm and Roma Peak with 222.8 mm
recorded their highest February daily rainfalls on record.
The pre-Nelson tropical Low moved to the east, skirting the
northern Top End coast of the Territory at 10 kts. The surface
circulation could be clearly seen in radar imagery as it passed close
to Cape Wessel, Northern Territory, late on 31 January. However,
continued development was held back by significant (20-kt plus)
upper-level easterly wind shear emanating from the Georgetown LOW’s
circulation. Upper-level wind shear continued to hinder the further
development of the LOW as it tracked into the central Gulf of
Carpentaria before pushing back to the SW under the influence of a
strengthening subtropical ridge to the south and east. For much of the
time the LLCC was located on the extreme eastern edge of the
convection and possibly broke in two at one point, reconsolidating
farther to the west as its deep cloud sheared off to the east and
south. By 4 February, the LOW was located close to the Northern
Territory coast near Vanderlin Island, approximately 50 nm ENE of
Borroloola, Northern Territory, (15.7S/137.1E) where it hovered for
approximately 18 hrs.
By this time upper-level conditions became more conducive for
development as a ridge relocated itself over the system, resulting in
improved upper-level outflow which allowed a CDO to develop over the
LLCC. The tropical LOW commenced a northeasterly path into the more
open water of the southern Gulf of Carpentaria and gradually
intensified. By 04/2100 UTC the tropical LOW had drifted back to the
SE as the monsoon flow over the Arafura Sea strengthened. The
developing LOW moved back into the Queensland AOR and was named
Nelson near 15.8S/139.0E (approximately 45 nm NNW of Mornington
Island, Queensland) at 2100 UTC 5 February.
B. Synoptic History
-------------------
The balance of Nelson’s synoptic history proved to be rather
straightforward as the cyclone moved to the E to ESE at 12 kts,
passing to the north of Mornington Island while slowly building into
a Category 2 cyclone. However, just prior to landfall, which
occurred at 06/1800 UTC just south of the mouth of the Gilbert River
(approximately 16.5S/141.3E, or 65 nm NNE of Karumba), a small
clockwise loop was observed. Peak intensity of 980 hPa with 55-kt
max 10-min avg winds was achieved at landfall. Although the cyclone
was initially predicted to track rapidly across northern Queensland
and redevelop in the Coral Sea, a new tropical Low developed just to
the east of Cairns, drawing away most of the moisture input into
Nelson. The cyclone decayed quickly, losing cyclone status at
07/0300 UTC (near 16.4S/142.3E, or 105 nm NE of Karumba). Ex-Nelson
dissipated soon thereafter over the southwestern Cape York Peninsula
as the new LOW off the tropical northeastern coast of Queensland
gradually accelerated away to the southeast.
C. Damage and Casualties
------------------------
There were no casualties reported from Nelson. However, all ten
crew members aboard a 5,000-tonne barge (MV Wunma) were winched to
safety to a bulk carrier after the zinc-carrying vessel was swamped
by huge seas whipped up by the cyclone while about 50 nm NW of
Karumba. The cyclone also whipped up large waves along the entire
western seaboard of the Gulf. At Weipa, well to the north of the
cyclone, waves were reported reaching as high as five metres.
Despite this, little overall damage was reported. No one was
reported as injured and there was no major flooding in local rivers.
Bitumen roads remained open. At Inkerman Station, which reported the
eye of the cyclone, a few palm trees were blown down and a tank blew
off a water