SWIO: EX ALENGA - Tropical Low

[Chacor]

Alenga now looking very, very good. JTWC sat fix is up to T5.0!

TPXS10 PGTW 080005

A. TROPICAL CYCLONE 01S (ALENGA)

B. 07/2330Z

C. 16.2S

D. 94.6E

E. TWO/MET7

F. T5.0/5.0/D2.0/24HRS STT: D1.0/06HRS

G. IR/EIR

H. REMARKS: 01A/PBO EYE/ANMTN. OW EYE SURR BY LG BANDING YIELDS
A 5.0 DT. RAPID DEVELOPMENT HAS OCCURRED SINCE 1730Z WHEN THE
EYE FEATURE FORMED. MET AND PT AGREE WITH DT. DBO DT.

I. ADDITIONAL POSITIONS: NONE


BELMONDO

[Chacor]

Perth has upgraded to a Severe Tropical Cyclone with 70 kt winds.

HIGH SEAS WEATHER WARNING FOR METAREA 10 ISSUED BY THE
AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE PERTH
AT 0106UTC 8 DECEMBER 2011

HURRICANE FORCE WIND WARNING

Please be aware, wind gusts can be a further 40 percent stronger than the
averages given here, and maximum waves may be up to twice the height.

SITUATION
At 0000 UTC Severe Tropical Cyclone Alenga was centred within 4 nautical miles
of
latitude sixteen decimal two south (16.2S)
longitude ninety four decimal nine east (94.9E)
Recent movement : east southeast at 19 knots
Maximum winds : 70 knots
Central pressure: 976 hPa

AREA AFFECTED
Within 80 nautical miles of the centre.

FORECAST
Maximum winds to 70 knots near the centre easing to 55 knots by 0000 UTC 09
December.

Winds above 48 knots within 40 nautical miles of centre with very rough to high
seas and moderate to heavy swell.

Winds above 34 knots within 80 nautical miles of centre with very rough seas
and moderate swell.

Forecast positions
At 1200 UTC 08 December: Within 35 nautical miles of 17.8 south 97.7 east
Central pressure 979 hPa.
Winds to 65 knots near centre.
At 0000 UTC 09 December: Within 65 nautical miles of 19.3 south 99.9 east
Central pressure 983 hPa.
Winds to 55 knots near centre.

REMARKS
All ships in the area please send weather reports every three hours.
Regular weather observing ships use normal channels.
Other ships please use either email to tcwcwa@bom.gov.au or fax to +61892632261
or satellite using SAC1241 through Land Earth Station Burum 312 [or 212 as
appropriate] via Perth.

Next warning will be issued by 0700 UTC 08 December 2011.

WEATHER PERTH

[Chacor]

Meanwhile SAB is up to T5.5:

TXXS21 KNES 080034
TCSSIO

A. 01S (ALENGA)

B. 08/0000Z

C. 16.3S

D. 94.8E

E. ONE/MET-7

F. T5.5/5.5/D2.0/24HRS

G. IR/EIR/TMI

H. REMARKS...SYSTEM HAS CONTINUED TO DEVELOP RAPIDLY. OW EYE IS EMBEDDED
IN B AND SURROUNDED BY W WHICH RESULTS IN A DT OF 6.0 AFTER 0.5 IS ADDED
FOR AN EYE ADJUSTMENT. MET IS 5.0 WHILE PT IS 5.5. AVERAGE RAW ADT VALUE
OF 5.6 OVER THE LAST 4HRS IS THE BASIS FOR THE FT OF 5.5. CONSTRAINTS
HAVE BEEN BROKEN DUE TO RAPID INTENSIFICATION.

I. ADDL POSITIONS

07/1913Z 15.5S 93.5E TMI


...RAMIREZ

[CrazyC83]

Those combined data support about 105 kt (1-min).

[CrazyC83]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 08 DEC 2011 Time : 013000 UTC
Lat : 16:27:23 S Lon : 95:27:22 E


CI# /Pressure/ Vmax
5.7 / 949.7mb/107.2kt


Final T# Adj T# Raw T#
5.4 5.0 4.6

Center Temp : -47.0C Cloud Region Temp : -64.4C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : INDIAN
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF

C/K/Z MSLP Estimate Inputs :
- Average 34 knot radii : 100km
- Environmental MSLP : 1005mb

Satellite Viewing Angle : 53.8 degrees

Weakening as fast as it strengthened.

[Chacor]

Perth went 80 kt at 06z:

AXAU01 APRF 080741
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0741 UTC 08/12/2011
Name: Severe Tropical Cyclone Alenga
Identifier: 01U
Data At: 0600 UTC
Latitude: 17.3S
Longitude: 96.8E
Location Accuracy: within 15 nm [30 km]
Movement Towards: east southeast [118 deg]
Speed of Movement: 20 knots [36 km/h]
Maximum 10-Minute Wind: 80 knots [150 km/h]
Maximum 3-Second Wind Gust: 110 knots [205 km/h]
Central Pressure: 968 hPa
Radius of 34-knot winds NE quadrant: 100 nm [185 km]
Radius of 34-knot winds SE quadrant: 80 nm [150 km]
Radius of 34-knot winds SW quadrant: 50 nm [95 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 40 nm [75 km]
Radius of 48-knot winds SE quadrant: 30 nm [55 km]
Radius of 48-knot winds SW quadrant: 20 nm [35 km]
Radius of 48-knot winds NW quadrant: 30 nm [55 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T4.5/5.0/D1.0/24HRS STT:W0.5/3HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 250 nm [465 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 08/1800: 19.1S 99.9E: 045 [085]: 060 [110]: 981
+24: 09/0600: 20.5S 101.9E: 075 [140]: 050 [095]: 986
+36: 09/1800: 21.2S 103.3E: 110 [200]: 045 [085]: 988
+48: 10/0600: 22.1S 104.3E: 140 [260]: 035 [065]: 995
+60: 10/1800: 22.6S 104.7E: 190 [345]: 030 [055]: 997
+72: 11/0600: 23.5S 105.2E: 235 [435]: 030 [055]: 997
REMARKS:
Severe Tropical Cyclone Alenga was located by microwave and visible satellite
imagery over the past 6 hours. Alenga appeared to peak near 0300 UTC with a well
defined eye with DVORAK DT of 5.0. In the last 3 hours the infa-red eye has
dissipated and embedded centre pattern [LG] gives a DVORAK DT of 4.5, consistent
with MET. CI held higher at 5.0. Max winds of 80 knots consistent with SATCON
although ADT has suggest higher intensities.

The WNW shear has increased above 10 knots and is likely to further increase in
the next 24 to 48 hours as an upper low and trough approach from the west.
Consequently Alenga should continue to weaken assisted by cooler SST's and a
possibly dryer airmass.

NWP guidance is quite consistent with general southeast motion likely over the
next 48 hours due to the upper trough. Gales may persist to the south of the
system in the tight easterly pressure gradient with a high pressure system
further south.



Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 08/1300 UTC by Perth TCWC.

[Chacor]

12Z:

AXAU01 APRF 081258
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1258 UTC 08/12/2011
Name: Severe Tropical Cyclone Alenga
Identifier: 01U
Data At: 1200 UTC
Latitude: 18.5S
Longitude: 98.6E
Location Accuracy: within 20 nm [35 km]
Movement Towards: east southeast [123 deg]
Speed of Movement: 21 knots [39 km/h]
Maximum 10-Minute Wind: 75 knots [140 km/h]
Maximum 3-Second Wind Gust: 105 knots [195 km/h]
Central Pressure: 969 hPa
Radius of 34-knot winds NE quadrant: 100 nm [185 km]
Radius of 34-knot winds SE quadrant: 80 nm [150 km]
Radius of 34-knot winds SW quadrant: 50 nm [95 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 40 nm [75 km]
Radius of 48-knot winds SE quadrant: 40 nm [75 km]
Radius of 48-knot winds SW quadrant: 40 nm [75 km]
Radius of 48-knot winds NW quadrant: 40 nm [75 km]
Radius of 64-knot winds: 25 nm [45 km]
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T4.0/4.5/D0.5/24HRS STT:W0.5/6HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 250 nm [465 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 09/0000: 20.6S 101.7E: 045 [085]: 050 [095]: 987
+24: 09/1200: 21.4S 103.2E: 075 [140]: 040 [075]: 991
+36: 10/0000: 21.9S 104.2E: 110 [200]: 035 [065]: 995
+48: 10/1200: 22.5S 104.9E: 140 [260]: 030 [055]: 997
+60: 11/0000: 23.2S 105.5E: 190 [345]: 030 [055]: 997
+72: 11/1200: 23.7S 105.8E: 235 [435]: 030 [055]: 996
REMARKS:
Severe Tropical Cyclone Alenga was located by microwave and visible satellite
imagery over the past 6 hours. Alenga appeared to peak near 0300 UTC with a well
defined eye with DVORAK DT of 5.0. In the last 3 hours the infa-red eye has
dissipated and embedded centre pattern [DG] gives a DVORAK DT of 4.0, pattern
adjusted MET is 3.5. CI held higher at 4.5 and 10 minute mean wind is set at 75
knots. ADT has begun to fall since peaking at a CI of 5.7 and is at 4.7 at 1130
UTC. SATCON has also dropped the intensity since 0700 UTC to a 10 minute mean
wind of 70 knots at 1000 UTC.

The WNW shear has increased above 10 knots and is likely to further increase
significantly in the next 12 to 24 hours as an upper low and trough approach
from the west. Consequently Alenga should continue to weaken assisted by cooler
SST's and a possibly dryer airmass.

NWP guidance is quite consistent with general southeast motion likely over the
next 48 hours due to the upper trough. Gales may persist to the south of the
system in the tight easterly pressure gradient with a high pressure system
further south.



Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 08/1900 UTC by Perth TCWC.

[Chacor]

AXAU01 APRF 081855
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1855 UTC 08/12/2011
Name: Tropical Cyclone Alenga
Identifier: 01U
Data At: 1800 UTC
Latitude: 19.6S
Longitude: 100.4E
Location Accuracy: within 30 nm [55 km]
Movement Towards: east southeast [123 deg]
Speed of Movement: 20 knots [38 km/h]
Maximum 10-Minute Wind: 60 knots [110 km/h]
Maximum 3-Second Wind Gust: 85 knots [155 km/h]
Central Pressure: 981 hPa
Radius of 34-knot winds NE quadrant: 80 nm [150 km]
Radius of 34-knot winds SE quadrant: 80 nm [150 km]
Radius of 34-knot winds SW quadrant: 80 nm [150 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 40 nm [75 km]
Radius of 48-knot winds SE quadrant: 40 nm [75 km]
Radius of 48-knot winds SW quadrant: 40 nm [75 km]
Radius of 48-knot winds NW quadrant: 40 nm [75 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T3.5/4.0/S0.0/24HRS STT:W0.5/6HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 250 nm [465 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 09/0600: 21.1S 102.6E: 050 [095]: 045 [085]: 989
+24: 09/1800: 21.6S 103.6E: 075 [140]: 035 [065]: 994
+36: 10/0600: 22.2S 104.6E: 110 [200]: 030 [055]: 998
+48: 10/1800: 22.8S 105.2E: 140 [260]: 030 [055]: 997
+60: 11/0600: 23.5S 105.6E: 190 [345]: 030 [055]: 996
+72: 11/1800: 24.1S 105.7E: 235 [435]: 030 [055]: 996
REMARKS:
Tropical Cyclone Alenga was located by microwave and IR satellite imagery over
the past 6 hours. Alenga appeared to peak near 0300 UTC with a well defined eye
with DVORAK DT of 5.0. In the last 6 hours the system has started to appear
sheared, with a shear pattern giving a DVORAK DT of 3.5. Due to a recent
convective blow-up, an embedded centre pattern yields 4.5 [LG]. Pattern adjusted
MET is 3.5 and has been favoured, resulting in FT of 3.5. CI held higher at 4.0
and 10 minute mean wind is set at 60 knots. ADT has begun to fall since peaking
at a CI of 5.7 and is at 3.6 at 1815 UTC.

The WNW shear has increased to 20-30 knots and is likely to further increase in
the next 12 hours as an upper low and trough approach from the west.
Consequently Alenga should continue to weaken, assisted by cooler SST's.

NWP guidance is quite consistent with general southeast motion likely over the
next 24 hours due to the upper trough, then possibly tending more southerly or
southwesterly as the system shears and the low level circulation is steered by
the surface ridge to the south. Gales may persist to the south of the system in
the tight easterly pressure gradient with a high pressure system further south.



Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 09/0100 UTC by Perth TCWC.

[Chacor]

AXAU01 APRF 090100
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 0059 UTC 09/12/2011
Name: Tropical Cyclone Alenga
Identifier: 01U
Data At: 0000 UTC
Latitude: 20.7S
Longitude: 102.6E
Location Accuracy: within 30 nm [55 km]
Movement Towards: east southeast [117 deg]
Speed of Movement: 20 knots [37 km/h]
Maximum 10-Minute Wind: 55 knots [100 km/h]
Maximum 3-Second Wind Gust: 75 knots [140 km/h]
Central Pressure: 984 hPa
Radius of 34-knot winds NE quadrant: 80 nm [150 km]
Radius of 34-knot winds SE quadrant: 80 nm [150 km]
Radius of 34-knot winds SW quadrant: 80 nm [150 km]
Radius of 34-knot winds NW quadrant: 80 nm [150 km]
Radius of 48-knot winds NE quadrant: 40 nm [75 km]
Radius of 48-knot winds SE quadrant: 40 nm [75 km]
Radius of 48-knot winds SW quadrant: 40 nm [75 km]
Radius of 48-knot winds NW quadrant: 40 nm [75 km]
Radius of 64-knot winds:
Radius of Maximum Winds: 15 nm [30 km]
Dvorak Intensity Code: T3.5/4.0/W0.5/24HRS STT:W1.0/12HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 250 nm [465 km]
Storm Depth: Deep
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: 09/1200: 22.0S 105.6E: 060 [110]: 045 [085]: 989
+24: 10/0000: 22.7S 107.4E: 090 [165]: 035 [065]: 995
+36: 10/1200: 23.3S 108.6E: 120 [225]: 030 [055]: 997
+48: 11/0000: 24.0S 109.8E: 155 [285]: 030 [055]: 997
+60: 11/1200: 24.8S 111.0E: 200 [375]: 025 [045]: 1000
+72: 12/0000: 25.9S 112.3E: 250 [465]: 025 [045]: 1000
REMARKS:
Tropical Cyclone Alenga was located by microwave and IR satellite imagery
overnight. In the last 6 hours the system has started to appear sheared, with a
shear pattern giving a DVORAK DT of 3.5 with CI held at 4.0. 10 minute mean wind
is set at 55 knots.

The system was able to keep pace with the WNW flow for most of the night and
continued as a small intense circulation. Over the past 6 hours shear has
started to affect the system and latest microwave and visible imagery suggests
that the low level and mid level circulations are begining to be displaced. The
WNW shear is currently around 30 knots and continues to increase during the day,
and assisted by cooler SST's Alenga should weaken below cyclone strength on
Saturday west of the mainland.

NWP guidance has become more aligned and has the system moving southeast over
the next 24-48 hours due to the upper trough. The low level centre may tend more
southerly or southwesterly as the system shears and gales could persist to the
south of the system in a tight easterly pressure gradient due to a high pressure
system further south.



Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 09/0700 UTC by Perth TCWC.

[Chacor]

Down to a Tropical Low.

AXAU01 APRF 091215
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by PERTH TROPICAL CYCLONE WARNING CENTRE
at: 1214 UTC 09/12/2011
Name: Ex-Tropical Cyclone Alenga
Identifier: 01U
Data At: 1200 UTC
Latitude: 21.5S
Longitude: 102.9E
Location Accuracy: within 20 nm [35 km]
Movement Towards: southeast [129 deg]
Speed of Movement: 8 knots [15 km/h]
Maximum 10-Minute Wind: 30 knots [55 km/h]
Maximum 3-Second Wind Gust: 45 knots [85 km/h]
Central Pressure: 995 hPa
Radius of 34-knot winds NE quadrant:
Radius of 34-knot winds SE quadrant:
Radius of 34-knot winds SW quadrant:
Radius of 34-knot winds NW quadrant:
Radius of 48-knot winds NE quadrant:
Radius of 48-knot winds SE quadrant:
Radius of 48-knot winds SW quadrant:
Radius of 48-knot winds NW quadrant:
Radius of 64-knot winds:
Radius of Maximum Winds:
Dvorak Intensity Code: T2.0/2.5/W2.0/24HRS STT: W0.5/6HRS
Pressure of outermost isobar: 1002 hPa
Radius of outermost closed isobar: 120 nm [220 km]
Storm Depth: Medium
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+12: : : : :
+24: : : : :
+36: : : : :
+48: : : : :
+60: : : : :
+72: : : : :

REMARKS:
Strong vertical wind shear has weakened Alenga below cyclone intensity. The low
level circulation centre [LLCC] appears elongated and is now well removed from
any convective cloud. The LLCC has decelerated to less than 10 knots, reducing
the translation speed component on the surface winds. By Dvorak standards the
centre is too weak to classify in terms of DT, however the adjusted MET is at
2.5 and weakening constraints hold the FT to 2.0 and CI to 2.5.

Gales remain a possibility to the south of the centre for a period owing to the
pressure squeeze associated with a strong ridge further to the south.





Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 09/1900 UTC by Perth TCWC.