GARY PADGETT'S
MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY
FEBRUARY, 2006
(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
--> Another intense tropical cyclone roams Southwest Indian waters
--> One hurricane in South Pacific east of Dateline
--> Couple of minor tropical cyclones form off northern Australia
--> Apparent tropical storm forms off coast of Brazil
*************************************************************************
********** EXTRA FEATURE **********
A COMPARISON BETWEEN THE AUSTRALIAN CYCLONE SEVERITY SCALE
AND THE SAFFIR/SIMPSON SCALE
----------------------------------------------------------
Both the U. S. National Weather Service and Australia's Bureau of
Meteorology (BoM) employ a 5-point scale by which to alert the public
of the general effects which can be expected from tropical cyclones of
varying intensities. In both systems tropical cyclones are classified
from Category 1 (the weakest) to Category 5 (the strongest), and each
scale seems to have been adopted enthusiastically by the general public
in both Australia and in the United States.
However, the scales are very different in their conception and in the
boundaries between their respective categories. The Saffir/Simpson
scale, used in the United States, is used for classifying tropical
cyclones which have reached hurricane intensity while the Australian
scale is utilized for all tropical cyclones of gale intensity or higher.
Nowadays, anyone anywhere in the world with internet access can follow
tropical cyclones in great detail, and there are many persons who delight
in tracking and discussing storms in all oceanic basins. Considerable
confusion has sometimes arisen when, for example, someone in the U. S.
is following an Australian cyclone and assuming that the category given
in the BoM warnings (and often aired in the international news media)
is equivalent to its Saffir/Simpson category.
The following chart summarizes the salient characteristics of the
two scales:
Characteristic Saffir/Simpson Australian
-------------------------------------------------------------------------
Beginning Point Hurricane force Gale force
Wind Parameter Sustained wind (1-min avg) Peak gusts
Wind Velocity Units Statute miles-per-hour Kilometres-per-hour
My purpose here is to provide information whereby persons interested
in comparing the two scales can easily do so. Table 1 defines the
Saffir/Simpson Scale in terms of the 1-min avg maximum sustained wind
(MSW) in statute miles-per-hour (mph) while Table 2 defines the
Australian Cyclone Severity Scale in terms of peak wind gusts in
kilometres-per-hour (km/hr). I have not included the narrative
describing the degree and type of damage which can be expected with
each category in both scales. Also, in both tables I have included
the qualifying wind velocity in nautical miles-per-hour (kts) along
with the nominal central pressure range in millibars (mb)--numerically
equal to hectopascals (hPa).
Table 1 - Saffir/Simpson Scale
==============================
Category 1-min avg MSW 1-min avg MSW Central Pressure
S/S (mph) (kts) (mb)
---------------------------------------------------------------------
1 74 - 95 64 - 82 >= 980
2 96 - 110 83 - 95 965 - 979
3 111 - 130 96 - 113 945 - 964
4 131 - 155 114 - 135 920 - 944
5 >= 156 >= 136 <= 919
Table 2 - Australian Cyclone Severity Scale
===========================================
Category Peak gusts Peak gusts Central Pressure
Aust (km/hr) (kts) (hPa)
---------------------------------------------------------------------
1 90 - 124 49 - 67 986 - 995
2 125 - 169 68 - 91 971 - 985
3 170 - 224 92 - 121 956 - 970
4 225 - 279 122 - 150 930 - 955
5 >= 280 >= 151 <= 929
The following two tables define each scale in terms of the other
scale's parameters, i.e., the Saffir/Simpson scale is defined in terms
of a 10-min avg MSW in kts, and peak gusts in kts and in km/hr (Table 3)
while the Australian scale is defined in terms of a 10-min avg MSW in
kts and a 1-min avg MSW in mph (Table 4).
Table 3 - Saffir/Simpson Scale in Terms of Australian Scale Parameters
======================================================================
Category 10-min avg MSW Peak Gusts Peak Gusts Equivalent
S/S (kts) (kts) (km/hr) Aust Category
-------------------------------------------------------------------------
1 56 - 72 79 - 101 146 - 190 mid-2 to mid-3
2 73 - 84 102 - 118 191 - 220 mid to high-3
3 85 - 99 119 - 140 221 - 260 high-3 to mid-4
4 100 - 118 141 - 166 261 - 310 mid-4 to mid-5
5 >= 119 >= 167 >= 311 mid to high-5
Table 4 - Australian Scale in Terms of Saffir/Simpson Scale Parameters
======================================================================
Category 10-min avg MSW 1-min avg MSW 1-min avg MSW Equivalent
Aust (kts) (kts) (mph) S/S Category
-------------------------------------------------------------------------
1 34 - 47 38 - 54 44 - 62 none
2 48 - 64 55 - 73 63 - 84 none to mid-1
3 65 - 85 74 - 96 85 - 111 mid-1 to high-2
4 86 - 106 97 - 120 112 - 139 low-3 to low-4
5 >= 107 >= 120 >= 140 mid-4 and up
Finally, as an additional aid to comparison, I have included a
table (Table 5) comparing each cyclone scale with the Dvorak scale,
used extensively in estimating tropical cyclone intensity from visible
and infrared satellite imagery. I have started the table with T2.0
since neither TPC/NHC nor the BoM TCWCs routinely issue advisories/
advices/warnings for systems less than that Dvorak rating. (See the
key following the table for an explanation of the abbreviations used.)
Table 5 - Comparison of Dvorak Scale with Cyclone Scales
========================================================
Dvorak MSW MSW TPC/NHC Australian
T-Number (1-min kts) (10-min kts) Category Category
-------------------------------------------------------------------
T2.0 30 26 TD TL
...................................................................
T2.5 35 31 TS TL
...................................................................
T3.0 45 40 TS TC-1
...................................................................
T3.5 55 48 TS TC-2
...................................................................
T4.0 65 57 H-1 TC-2
...................................................................
T4.5 77 68 H-1 TC-3
...................................................................
T5.0 90 79 H-2 TC-3
...................................................................
T5.5 102 90 H-3 TC-4
...................................................................
T6.0 115 101 H-4 TC-4
...................................................................
T6.5 127 112 H-4 TC-5
...................................................................
T7.0 140 123 H-5 TC-5
...................................................................
T7.5 155 136 H-5 TC-5
...................................................................
T8.0 170 150 H-5 TC-5
-------------------------------------------------------------------
Key to Abbreviations:
---------------------
TD tropical depression
TL tropical LOW
H-n hurricane of Saffir/Simpson category "n"
TC-n tropical cyclone of category "n" on Australian scale
Most of the information presented above was obtained from the
websites of Australia's Bureau of Meteorology and the Tropical
Prediction Center/National Hurricane Center. A special thanks to
Michael Bath for providing information regarding the nominal central
pressures corresponding to the Australian scale categories as well
as making some suggestions concerning formatting and presentation
of the tables.
*************************************************************************
ACTIVITY BY BASINS
ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico
Activity for February: No tropical cyclones
*************************************************************************
SOUTH ATLANTIC (SAT) - Atlantic Ocean South of the Equator
Activity for February: 1 possible tropical cyclone
South Atlantic Tropical Activity for February
---------------------------------------------
In late February what appeared to be a small tropical storm developed
of the coast of southeastern Brazil, but unlike the devastating Catarina
of March, 2004, moved away from the coastline with no effects on land.
According to Toni Cristaldi of the Melbourne, FL, NWS Forecast Office,
in its formative stages on 20 February the system for a brief period of
time drifted erratically south-southwestward, parallel to the Brazilian
coastline. On the 21st it began a general eastward motion which would
continue throughout its short lifetime.
Based on an analysis of available satellite imagery by Dr. Karl Hoarau
of Cergy-Pontoise University near Paris, the system intensified quickly
on the 22nd and reached a peak intensity of 55 kts around 23/0000 UTC at
a point approximately 225 nm due east of Porto Alegre, Brazil. Following
this, the system encountered strong westerly and southwesterly shear and
weakened quickly. Following is a track and intensity history recently
compiled by Karl. (A special thanks to Karl for taking the time to
prepare the track.)
Storm Name: None Cyclone Number: None Basin: SAT
Date Time Lat Lon Cent MSW MSW Remarks
(GMT) Press 1-min 10-min
(mb) (kts) (kts)
-------------------------------------------------------------------------
06 FEB 21 1200 30.8 S 49.7 W 20
06 FEB 21 1800 31.1 S 49.3 W 25
06 FEB 22 0000 31.3 S 49.0 W 25
06 FEB 22 0600 31.4 S 48.6 W 25
06 FEB 22 1200 31.1 S 48.2 W 30
06 FEB 22 1800 30.7 S 47.8 W 35
06 FEB 22 2100 30.3 S 47.4 W 45
06 FEB 23 0000 30.0 S 46.9 W 55
06 FEB 23 0600 29.4 S 45.6 W 50
06 FEB 23 1200 29.2 S 44.3 W 45
06 FEB 23 1800 29.1 S 42.6 W 40
06 FEB 23 2100 29.1 S 41.6 W 30
*************************************************************************
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 tropical storm
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 February
-----------------------------------------------------
As the month of February opened, Tropical Cyclone Boloetse was gaining
strength in the southern Mozambique Channel before making a very close
approach to southwestern Madagascar. The full report on Boloetse may be
found in the January summary. Shortly after mid-month a system formed
quickly near Mauritius and was designated Tropical Storm 09 by MFR and
TC-12S by JTWC. Mauritius, however, did not upgrade the system to
tropical storm status so no name was assigned. During the final week
of February and into the opening days of March, Intense Tropical Cyclone
Carina tracked southward through the eastward part of the basin,
attaining great intensity (115 kts 10-min avg per MFR/130 kts 1-min avg
per JTWC) but fortunately remaining far from populated areas. Reports
on both Tropical Storm 09 and Tropical Cyclone Carina follow.
TROPICAL STORM
(MFR-09 / TC-12S)
19 - 21 February
-------------------------------------
A. Storm History
----------------
The regular STWO for 18 February issued by JTWC noted that an area of
convection had formed approximately 340 nm east-northeast of Antanana-
rivo, Madagascar. QuikScat data showed an elongated area of troughing,
and water vapor imagery indicated that an upper-level trough was limiting
convection on the northern periphery of the surface trough while serving
to enhance convection along the southern periphery. The development
potential was assessed as 'poor', but this was upgraded to 'fair' at
0700 UTC on 19 February as multi-spectral satellite imagery revealed a
well-defined and tight LLCC with increasing deep convection. At 19/0600
UTC MFR issued the first bulletin on Tropical Disturbance 09, placing
the center approximately 200 nm northwest of Mauritius. The system
began to intensify fairly rapidly--MFR upgraded it to a 30-kt tropical
depression at 19/1200 UTC and JTWC issued a TCFA at 1430 UTC.
At 19/1800 UTC MFR upgraded the depression to a 40-kt tropical storm
centered about 75 nm north-northwest of Mauritius. At the same time,
JTWC issued their first warning on TC-12S with the 1-min avg MSW
estimated at 45 kts. Tropical Storm 09 was moving southeastward at
about 12 kts due to its being under the steering influence of a ridge
located to the northeast. Despite its rapid intensification spurt early
on the 19th, the tropical storm did not intensify further and soon began
to weaken as it entered an unfavorable shear environment. The system
swung to more of an easterly track, halted, described a tiny clockwise
loop, and then drifted northwestward as it weakened. MFR downgraded
Tropical Storm 09 to a tropical depression at 1200 UTC on 20 February,
and JTWC issued their final warning six hours later. Shear had separated
the remaining convection nearly 90 nm from the LLCC. MFR further down-
graded the system to a 25-kt tropical disturbance at 21/0000 UTC and
issued their final bulletin, placing the center approximately 85 nm
north of Mauritius.
A graphic depicting the track of Tropical Storm 09 may be found at
the following link: 2006-12S-NONAME.gif
No damages or casualties are known to have resulted from this system.
B. Discussion: Why Wasn't This System Named?
---------------------------------------------
In the Southwest Indian Ocean west of longitude 90E, Meteo France
La Reunion (MFR) serves as the WMO's Regional Specialised Meteorological
Centre (RSMC) for the basin, receiving this designation sometime in the
early 1990s. However, the meteorological services of Mauritius and
Madagascar began naming tropical cyclones in this region in 1960, working
from a common list of names with longitude 55E being the demarcation
line. At the time that MFR was designated the RSMC, apparently, as a
conciliatory gesture due to the long-standing practice, Mauritius and
Madagascar were designated as Sub-regional Tropical Cyclone Advisory
Centres and allowed to continue the actual assigning of names to tropical
systems in this basin. MFR only advises these agencies regarding the
intensity of tropical systems.
Most of the time there is agreement between MFR and the Sub-regional
Centre in question and the name is applied on the first MFR bulletin
upgrading a depression to tropical storm status. However, from time to
time Mauritius or Madagascar doesn't name a system which MFR has upgraded
to a tropical storm, and conversely, there have been occasions when one
of the Sub-regional Centres has named a tropical depression which MFR
had not yet classified as a tropical storm.
This particular case is interesting because of a Weather News bulletin
issued by the Mauritius Meteorological Office around 1300 UTC on the 19th
of February:
"A midget storm is approaching Mauritius from the north-west and at
0400 hrs this afternoon (1200 UTC) it was centered at about 220 km to the
north-west of Mauritius in latitude 18.5S and longitude 56.2E and is
moving in a southeast direction at about 20 km/hr. Forecast for the next
24 hours: weather will gradually deteriorate over Mauritius with
scattered showers heavy at times and isolated thunderstorms. Gusts of
the order of 60 km/hr (32 kts) will gradually increase to reach more
than 100 km/hr (54 kts) at night."
Applying the most commonly-used gust-to-MSW (10-min avg) reduction
factor (1.41), peak gusts of 54 kts would imply a 10-min mean wind of
38 kts--above gale force. Dvorak ratings from JTWC and MFR both reached
T3.0 late on the 19th and early on the 20th, and satellite intensity
estimates from SAB were at 35 kts (T2.5).
So it isn't exactly clear why the Mauritius Meteorological Office
chose not to name this system. The forecast peak gusts of 54 kts seem to
imply a minimal tropical storm, although those were admittedly a forecast
and not a current analysis. Also, the agency could have adopted a
wait-and-see policy, and the system did begin to weaken fairly quickly.
However, the term "midget storm" in the Weather News bulletin makes
one wonder if perhaps Mauritius has some sort of minimum size criterion
for qualifying a system as a bona fide tropical storm. Tropical Storm 09
was a small system, but not unusually so. JTWC estimated the gale radius
at 60 nm, while MFR's radius of gales was considerably smaller at 20 nm.
However, according to some information received several years ago from
Jeff Callaghan at BoM Brisbane, the incredibly devastating Tropical
Cyclone Tracy which devastated Darwin in 1974 had a gale radius of only
18 nm.
If anyone reading this discussion can shed any more light on the
question raised above, I'll be happy to report on it in a future summary.
(Report written by Gary Padgett)
INTENSE TROPICAL CYCLONE CARINA
(MFR-10 / TC-14S)
23 February - 3 March
---------------------------------------------------
Carina: contributed by Mauritius
A. Introduction and Storm Origins
---------------------------------
Intense Tropical Cyclone Carina became the strongest tropical cyclone
of the 2005-2006 season in the Southwest Indian Ocean, at least as of
20 April 2006. The storm almost reached the superlative classification
of "very intense tropical cyclone" per MFR's analysis, and equalled
a Western Pacific super typhoon per JTWC's nomenclature. Fortunately,
Carina pursued a track which kept it several hundred miles distant from
any islands.
Early on 22 February an area of convection which had appeared the
previous day was located approximately 565 nm east of Diego Garcia.
The convective signature was improving with bands of deep convection
on the northern and southern periphery rotating cyclonically toward
a developing LLCC. An upper-level analysis indicated low vertical
shear and the possible development of anticyclonic outflow directly
above the disturbance. JTWC assessed the potential for further
development as 'fair'. MFR initiated bulletins on Tropical
Disturbance 10 at 0000 UTC on 23 February, locating the center about
550 nm east-southeast of Diego Garcia. The system was moving slowly
in a general southerly direction, and intensification continued at a
steady pace. JTWC issued a TCFA at 23/0330 UTC and MFR upgraded the
disturbance to a 30-kt tropical depression at 0600 UTC. At the same
time, JTWC issued their first warning on TC-14S, estimating the 1-min
avg MSW at 35 kts.
B. Synoptic History
-------------------
MFR upgraded the depression to tropical storm status at 23/1800 UTC
with Mauritius assigning the name Carina. Tropical Storm Carina at this
juncture was located about 575 nm east-southeast of Diego Garcia and
was quasi-stationary. On the 24th the storm embarked on a southwesterly
course under the steering influence of a deep-layer ridge to the east.
Carina intensified quite slowly over the next couple of days. Vertical
shear was low, but upper-level outflow was less than ideal. JTWC upped
the 1-min avg MSW to 70 kts at 25/0600 UTC, but MFR did not upgrade
Carina to tropical cyclone (i.e., hurricane) status until 1200 UTC on
26 February. At this time the cyclone's center was located approximately
565 nm southeast of Diego Garcia, moving south-southwestward at 4 kts.
On the 26th and 27th Carina moved almost due southward due to the
influence of an anticyclone situated to the east, but a return to a
southwesterly trajectory was anticipated in a couple of days as a
secondary anticyclone was forecast to become established poleward of
the cyclone. A NOAA-15 EIR picture taken at 26/0025 UTC revealed
some very cold cloud tops associated with Carina. Several tops were
at least -100 C with the coldest at -102.3 C near the cyclone's center.
Carina continued to intensify steadily and reached its peak intensity
of 115 kts (10-min avg) with an estimated CP of 910 hPa at 1200 UTC on
28 February. JTWC's peak 1-min avg MSW of 130 kts correlates very well
with MFR's peak intensity. Had Carina's 10-min avg MSW increased by
5 kts more, it would have been classified as a "very intense tropical
cyclone"--the highest classification on MFR's scale. At the time of its
peak intensity Carina was centered about 650 nm southeast of Diego
Garcia, moving slowly southwestward at 5 kts. The slow southwesterly
motion continued until around 0000 UTC on 2 March, when Carina made an
abrupt turn to the southeast. After peaking in intensity the cyclone
weakened very slowly at first, then rather rapidly as vertical shear
increased and the outflow became disrupted. JTWC's 1-min avg MSW dropped
from 115 kts at 0600 UTC on 1 March to 65 kts twelve hours later. MFR's
intensity fell from 110 kts to 75 kts during the same period. Carina
was downgraded to a 55-kt tropical storm at 02/1200 UTC as it appeared
to describe a small clockwise loop.
JTWC issued their final warning at 02/1800 UTC. A 02/1540 UTC SSM/I
pass had depicted a fully-exposed LLCC nearly 135 nm to the northwest
of the convection. MFR issued bulletins on Carina for another 18 hours,
downgrading the system to a tropical disturbance and issuing the final
bulletin at 03/1200 UTC. The weak 25-kt center was then estimated to
be about 900 nm east of Rodrigues Island.
A graphic depicting the track of Intense Tropical Cyclone Carina may
be found at the following link: 2006-14S-CARINA.gif
C. Damage and Casualties
------------------------
As Carina was a completely marine cyclone remaining far from any
populated areas, there have no reports of damages or casualties resulting
from the cyclone.
(Report written by Gary Padgett)
*************************************************************************
NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E
Activity for February: 1 tropical cyclone
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.
TROPICAL CYCLONE EMMA
(TC-15S)
26 - 28 February
-----------------------------------------
A. Origins and Synoptic History
-------------------------------
Tropical Cyclone Emma was a short-lived, minimal tropical cyclone
which made landfall near Onslow, Western Australia, on the final day
of February. A weak tropical LOW had formed as early as 22 February
southeast of Java near 12.0S/119.0E, but wasn't expected to develop
into a tropical cyclone anytime within the next few days. On the 24th
a monsoon trough extended east-west in the Timor Sea along latitude
12S, and a LOW was expected to form over the next couple of days in
the vicinity of longitude 115E with a high probability of tropical
cyclogenesis during the succeeding days. BoM Perth began issuing
shipping warnings and tropical cyclone advices at 0000 UTC on
26 February for a developing tropical LOW located about 450 nm north
of Karratha, moving slowly southward. The system continued generally
southward over the next couple of days with a couple of relocations.
The initial intensity of 25 kts was upped to 30 kts at 26/1200 UTC,
and a STWO issued by JTWC at 1800 UTC noted that a 26/1018 UTC QuikScat
pass had depicted a very broad LLCC with a uniform wind field of 15 to
20 kts along the periphery and lighter winds near the center--a feature
typical of monsoon LOWs. A 26/1459 UTC AMSU-B image revealed that most
of the deep convection was confined to the periphery of the circulation.
An upper-level analysis revealed that an upper-level anticyclone lay
over the surface LLCC, and with low vertical shear and excellent radial
outflow, the potential for development was rated as 'fair'. BoM Perth
upgraded the LOW to Tropical Cyclone Emma at 1200 UTC on 27 February,
placing the center about 165 nm north of Onslow and moving southward
at an increased pace of about 14 kts. JTWC issued the first of only
two warnings on Emma at 27/1800 UTC, numbering the system as TC-15S.
The remarks noted that deep convection had recently migrated from the
periphery of the circulation to near the LLCC.
Tropical Cyclone Emma reached an estimated peak intensity of 40 kts
(10-min avg) at 27/1800 UTC and this was maintained until landfall
around 0300 UTC 28 February just west of Mardie. The final tropical
cyclone advice on Emma was issued at 28/0600 UTC and placed the center
about 130 km east-southeast of Onslow, moving south-southeastward at
28 km/hr (15 kts). This advice downgraded Emma to a 30-kt tropical
LOW and further weakening was anticipated.
A graphic depicting the track of Tropical Cyclone Emma may be found
at the following link: 2006-15S-EMMA.gif
B. Meteorological Observations
------------------------------
Matthew Saxby has sent me some files of observations downloaded from
BoM's website. The most notable 24-hour rainfall measured in association
with Tropical Cyclone Emma was 190 mm at Karratha in the 24 hours ending
at 9:00 AM (presumably local time) on 28 February.
Following are the peak winds observed at various weather stations in
the region. The criterion for inclusion was that gusts exceeding 40 kts
and/or sustained winds exceeding gale force were recorded
Station Date Time Peak Sustained Peak Gust
(UTC) (10-min avg kts) (3-sec kts)
------------------------------------------------------------------------
Barrow Island 27 Feb 2030 41 49
Bulga Downs 28 Feb 2200 40 --
Karratha 27 Feb 1918 -- 43
Legendre Island 27 Feb 1600 42 --
Meekatharra 28 Feb 1800 -- 45
Mount Magnet 28 Feb 1843 -- 40
Onslow Airport 28 Feb 0125 -- 40
Port Hedland 27 Feb 2132 40 48
Roebourne 27 Feb 2000 35 47
C. Damage and Casualties
------------------------
No reports of damage or casualties resulting from Tropical Cyclone
Emma have been received.
(Report written by Gary Padgett)
*************************************************************************
NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E
Activity for February: 1 tropical cyclone
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.
TROPICAL CYCLONE KATE
(TC-13P)
22 - 24 February
-----------------------------------------
A. Origins and Synoptic History
-------------------------------
Tropical Cyclone Kate was a short-lived cyclone in the far north-
western Coral Sea. Kate originated from a weak tropical LOW embedded
in the monsoon trough near Torres Strait. On 22 February the LOW
rapidly intensified as it tracked eastwards.
By 22/1800 UTC the LOW was located near 10.8S/144.5E (approximately
130 nm east of Thursday Island, Australia) with a CP of 995 hPa. Gales
had wrapped around the LLCC and BoM Brisbane code-named the new cyclone
Kate.
The cyclone continued to drift to the east-southeast at 7 kts as
it was steered by the near-equatorial ridge to the north. The peak
intensity of 985 hPa with a MSW of 50 kts (10-min avg) was achieved
near 11.3S/146.4E, or approximately 120 nm south-southwest of Port
Moresby, New Guinea, at 23/0600 UTC. Soon after, Kate stalled and
strong vertical wind shear ripped the cyclone's convective structure
away to the southeast of the LLCC. By 24/0000 UTC, Kate had lost
cyclone status near 11.3S/146.5E. Peripheral gales persisted to the
east and south of the LLCC for a further 24 hours before the remnant
LOW dissipated.
A graphic depicting the track of Tropical Cyclone Kate may be
found at the following link: 2006-13P-KATE.gif
A satellite image of Kate is available at:
http://earthobservatory.nasa.gov/NaturalHazards/shownh.php3?img_id=13379
B. Damage and Casualties
------------------------
The cyclone inflicted rough seas through the Torres Strait Islands
and along the southern coastline of Papua New Guinea. In the Torres
Strait Islands, high tides and rough seas caused further erosion
adding to that caused by Tropical Cyclone Ingrid of March, 2005, and
the unnamed Port Moresby cyclone of April, 2005 (see reports on those
cyclones in their respective monthly summaries) and the gales of July
2005. This erosion washed away a jetty.
Following is an excerpt from a press release describing the damage
caused to southern Papua New Guinea by gales in July, 2005. A very
large HIGH over New South Wales caused gales from the northern Coral
Sea to southern Papua New Guinea.
"It is understood that king tides caused havoc in Western and Gulf
provinces of Papua New Guinea. More than 200 houses, mostly in
Western Province and at least one village on the Gulf and Central
Province were reported as having been destroyed by surging high
tides. Rising tides and rough seas also affected the Madang, New
Ireland and Milne Bay provinces. Unprecedented levels of water had
swept into food gardens on Carteret Island, Mortlocks and Tasman
Islands in Bougainville and in some of the Trobriand Islands. Ten
fishermen were reported as missing near Daru."
(Report written by Simon Clarke, based in part upon information supplied
by Jeff Callaghan of the Brisbane TCWC)
*************************************************************************
SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E
Activity for February: 3 tropical depressions
1 tropical cyclone of hurricane intensity
Sources of Information
----------------------
The primary sources of tracking and intensity information for
South Pacific tropical cyclones are the warnings and advisories
issued by the Tropical Cyclone Warning Centres at Nadi, Fiji (for
waters north of latitude 25S), and Wellington, New Zealand (for
waters south of latitude 25S). References to sustained winds imply
a 10-minute averaging period unless otherwise stated.
In the companion tropical cyclone tracks file, I occasionally
annotate positions from warnings issued by the Joint Typhoon Warning
Center (JTWC) of the U. S. Air Force and Navy, located at Pearl
Harbor, Hawaii, when they differ from the Southern Hemisphere
centres' coordinates by usually 40-50 nm or more. The JTWC warnings
are also the source of the 1-minute average maximum sustained wind
values included in the tracks file. Additionally, information
describing details of satellite imagery and atmospheric circulation
features included in the narratives is often gleaned from the JTWC
warnings.
South Pacific Tropical Activity for February
--------------------------------------------
As the month of February opened the remnants of January's Tropical
Cyclone Jim were loitering about over the ocean southeast of New
Caledonia, but redevelopment was not expected and none occurred. The
only named cyclone to form was Vaianu, which formed during the 2nd week
of the month between Fiji and Samoa and reached hurricane intensity,
affecting some of the islands of the Kingdom of Tonga and causing
significant agricultural losses. A report on Tropical Cyclone Vaianu,
written by Simon Clarke, follows.
Three additional tropical depressions were tracked by RSMC Nadi during
February. The first of these, Tropical Depression 10F, was first noted
at 0600 UTC on 2 February when it was centered only about 80 nm south-
west of Niue. Diffluence over the system was good but shear was too
strong for it to ever consolidate its associated convection near the
LLCC. TD-10F moved erratically in a general southerly direction over
the next couple of days and was last referenced at 0600 UTC on the 4th,
at which time it had moved to a position about 400 nm southeast of
Tongatapu. Warnings were issued for peripheral gales in the eastern
semicircle on 3 and 4 February. A graphic depicting the track of this
depression may be found at the following link: 2006-10F.gif
Tropical Depression 11F had formed by 2100 UTC on 8 February about
150 nm southwest of Pago Pago, American Samoa. This system drifted
slowly south and southwestward over the next couple of days. Vertical
shear was not particularly high and some models forecast this system
to develop, but it appears that interference from the developing TD-12F
to the northwest, which became Tropical Cyclone Vaianu, was a primary
inhibiting factor to further development. The last reference to TD-11F
was at 10/2100 UTC and placed the center approximately 225 nm west-
southwest of Niue. A graphic depicting the track of this depression may
be found at the following link: 2006-11F.gif
Tropical Depression 13F was a persistent but weak system which roamed
waters from east of the Solomons to well south of Fiji for nearly a
week in late February. TD-13F was located about 365 nm east-southeast
of Guadalcanal at 2100 UTC on 19 February, and over the next several days
moved slowly in a general southeasterly direction, passing between
Vanuatu and Fiji on the 22nd and 23rd. The system became quasi-
stationary to the south of Fiji on the 25th and was last referenced
by the Nadi TCWC at 25/1800 UTC, when it was located roughly 400 nm
south-southwest of Viti Levu. As is often the case with these South
Pacific depressions forming in a monsoon trough, vertical shear was
sufficiently strong to prevent TD-13F from developing as a tropical
cyclone. Winds near the center were never estimated stronger than
25 kts, although as the system moved southward toward a subtropical
ridge, the increasing pressure gradient was responsible for causing
some peripheral gales well south of the center. A graphic depicting
the track of this depression may be found at the following link:
2006-13F.gif
TROPICAL CYCLONE VAIANU
(TD-12F / TC-11P)
9 - 19 February
-------------------------------------------
A. Storm Origins
----------------
Early in February, an active area of convergence developed across
the Southeast Pacific from the Solomon Islands through to Tonga. On
9 February an eastward-moving tropical LOW developed approximately
80 nm to the north-northeast of Vanua Levu. As the LOW continued to
track steadily to the east, early development was hampered by strong
upper-level shear of 20 to 25 kts. The main convective band remained
about 1 degree to the east of the LLCC. By 10/1200 UTC, the LOW was
located just 30 nm to the north of Niuafo'ou and commenced a path to
the south-southeast, slowly strengthening over seas of 29-30 C. The
upper-level outflow was diffluent and the system tracked into an area
of decreasing shear to its south.
B. Synoptic History
-------------------
By 11/1100 UTC, organization had undergone marked improvement with
the primary convective band wrapping around the LLCC. The LOW was
upgraded to cyclone status and named Vaianu. At this time the
cyclone was located near 17.4S/174.9W, approximately 85 nm southwest
of Niuatoputapu, and had swung back to a 5-kt southwesterly path,
being steered by a mid-level ridge to the southeast. The cyclone
continued to track in a southwesterly direction at 7 kts over the
open ocean to the west of the Tongan group of islands while slowly
strengthening as the upper-level wind shear relaxed. Peak intensity
of 965 hPa with an estimated MSW (10-min avg) of 70 kts was reached
at 13/1200 UTC at 21.7S/177.0W, or approximately 105 nm west-southwest
of Tongatapu, and this intensity was sustained for a further 24 hours
as Vaianu swung onto a southward track midway between Ono-i-lau (in
Fiji's Lau archipelago) and Tongatapu (passing about 100 nm from each).
The cyclone eventually re-curved to the southeast at 10 kts, being
steered by a mid-level ridge to the northeast and by a broad 250-hPa
trough to the west. The storm gradually weakened due to increasing
wind shear and cooler SSTs. Vaianu lost cyclone status whilst
undergoing extratropical transition near 29.0S/167.0W, or roughly 600
nm southwest of Rarotonga, at 16/1200 UTC, but remained a powerful low
pressure system for several days thereafter while tracking generally
to the east over open ocean.
A graphic depicting the track of Tropical Cyclone Vaianu may be
found at the following link: 2006-11P-VAIANU.gif
Satellite images of Vaianu can be found at:
http://earthobservatory.nasa.gov/NaturalHazards/shownh.php3?img_id=13369
http://visibleearth.nasa.gov/view_rec.php?id=8376
C. Damage and Casualties
------------------------
Vaianu managed to move between the islands on its path across the
South Pacific, and as a consequence the main impacts of the cyclone
were associated with torrential rain and gale-force winds.
Tropical food crops were hard hit by Vaianu, particularly in
Tongatapu and Eua, with 70% of the banana and breadfruit crops being
wiped out. Sea water intruded inland about 100 m on the northwestern
side of Tongatapu. However, little damage to property was reported.
There were no reports of any significant damage to housing.
Electricity supplies were knocked out in many areas along Vaianu's
path and this took about a week to restore to all outer villages and
nearby islands.
Flooding was reported in low-lying areas of Tonga's capital,
Nuku'alofa, "shutting down" the city for two days. Shops and offices
were closed with windows boarded up as Vaianu passed by approximately
55 nm to the east.
The remaining Tongan islands were affected by strong winds,
thunderstorms and very rough seas but no substantial damage or
injuries were reported.
(Report written by Simon Clarke)
*************************************************************************
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
*************************************************************************
*************************************************************************
Posted: 05.02.06 / Typhoon2000.ph, Typhoon2000.com