SIO: ILSA - Post-Tropical

[cycloneye]

HWRF doing what it ussually does.

[Iceresistance]

This my be already messing up the SOI index. Daily SOI is at +23

[Hurricane2022]

 https://twitter.com/zeb199818/status/1644349831929012225



 https://twitter.com/zeb199818/status/1644353938890854402

[cycloneye]

 https://twitter.com/JointCyclone/status/1644382381560692748

[aspen]

HWRF doing what it ussually does.

https://i.imgur.com/iC8dJg9.png

HWRF outputs of <915mb are pretty rare these days. Seems like the ceiling for this is high, depending on how shear progresses.

[cycloneye]

THE AREA OF CONVECTION (INVEST 98S) PREVIOUSLY LOCATED NEAR
8.8S 131.1E, IS NOW LOCATED NEAR 9.4S 130.0E, APPROXIMATELY 189 NM NORTH-
NORTHWEST OF DARWIN, AUSTRALIA. ENHANCED INFRARED SATELLITE IMAGERY SHOWS
A CONSOLIDATING SYSTEM WITH DEEP CONVECTION SHEARED SOUTHWESTWARD OF A
PARTLY EXPOSED LOW LEVEL CIRCULATION. A 071319Z ASCAT METOP-B PASS SHOWS
AN AREA OF 25-30KT WINDS ALONG THE NORTH AND WEST SECTORS. ENVIRONMENTAL
ANALYSIS REVEALS MARGINALLY FAVORABLE CONDITIONS FOR INTENSIFICATION WITH
STRONG (30-KT) VERTICAL WIND SHEAR OFFSET BY WARM (29-30C) SST AND STRONG
POLEWARD OUTFLOW. ADDITIONALLY, THE INVEST IS CURRENTLY IN A REGION THAT
HAS SUPPORT FROM A WEAK MJO SIGNAL. MODELS ARE IN GENERAL AGREEMENT THAT
98S WILL CONTINUE ON A SOUTHWESTWARD TRACK INTO AN AREA OF LOWER VWS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 30 TO 34 KNOTS. MINIMUM
SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 997 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS
HIGH.

[zzzh]

[Hurricane2022]

BOM is already forecating a 100 kt (10-min) winds at peak intensity!

FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
(UTC) : degrees : nm (km): knots(km/h): hPa
+06: 08/0600: 10.0S 129.4E: 040 (070): 030 (055): 1002
+12: 08/1200: 10.3S 129.0E: 050 (095): 030 (055): 1003
+18: 08/1800: 10.6S 128.7E: 060 (115): 030 (055): 1003
+24: 09/0000: 11.0S 128.2E: 075 (135): 035 (065): 1003
+36: 09/1200: 11.8S 127.0E: 090 (170): 035 (065): 1000
+48: 10/0000: 12.5S 125.3E: 105 (195): 040 (075): 998
+60: 10/1200: 13.5S 123.5E: 125 (235): 050 (095): 992
+72: 11/0000: 14.5S 122.0E: 150 (280): 060 (110): 985
+96: 12/0000: 16.4S 120.0E: 170 (315): 080 (150): 967
+120: 13/0000: 19.0S 119.9E: 200 (370): 095 (175): 950
REMARKS:
Developing tropical low (23U) likely to become a severe tropical cyclone in
coming days.
Position based on visible imagery on the eastern edge of deep convection,
consistent with ongoing high easterly wind shear.

Earlier ASCAT showed 30kn under the deep convection west of the centre.

Intensity 30kn based on the ASCAT. Dvorak FT/CI=2.0, based on steady (S)
development in MET, though DT using shear pattern is more 2.5-3.0. No
significant curved band evident. Likely convection will fluctuate diurnally so
some weakening during daytime for DT is possible in next 6h.

Forecast track is based on a standard consensus of guidance. Steering is
dominated by a mid-level anti-cyclone to the southeast. This sees slow movement
to the southwest at the movement, a little faster and west southwest starting
Sunday then a turn to south on Wednesday. On Thursday, an approaching upper
trough could steer it faster and to the southeast, but this could be after
landfall.

The strong wind shear should constrain development in the short term but as the
system moves further south, then is expected to reduce. Forecast rate of
development is less than standard, increasing to standard from Monday morning.
This results in a forecast intensity of category 4 (100 kts) at landfall. Upper
outflow could be favourable to very favourable for a period and some sources of
guidance indicate a higher intensity is possible. Ocean temperatures in the
area of forecast land fall are very at the moment.

[cycloneye]

First forecast so this will be changing with time.

[Yellow Evan]

Been a TS for over a day now. Not sure what is taking the JTWC so long.

Upper setup looks toasty with very divergent flow and a jet interaction. Sub-outflow layer is where we have to watch for directional shear, however.

[cycloneye]

TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0727 UTC 08/04/2023
Name: Tropical Low
Identifier: 23U
Data At: 0600 UTC
Latitude: 9.7S
Longitude: 129.3E
Location Accuracy: within 20nm (35 km)
Movement Towards: west southwest (256 deg)
Speed of Movement: 4 knots (8 km/h)
Maximum 10-Minute Wind: 35 knots (65 km/h)
Maximum 3-Second Wind Gust: 50 knots (95 km/h)
Central Pressure: 996 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: 40 nm (75 km)
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: nm ( km)
Radius of Maximum Winds: nm ( km)
Dvorak Intensity Code: T2.5/2.5/D1.0/24HRS STT:D05/06HRS
Pressure of outermost isobar: 1004 hPa
Radius of outermost closed isobar: 60 nm (110 km)
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
(UTC) : degrees : nm (km): knots(km/h): hPa
+06: 08/1200: 10.2S 129.3E: 040 (070): 035 (065): 996
+12: 08/1800: 10.6S 129.0E: 050 (090): 035 (065): 996
+18: 09/0000: 10.9S 128.5E: 060 (110): 035 (065): 996
+24: 09/0600: 11.3S 127.9E: 070 (130): 035 (065): 997
+36: 09/1800: 12.0S 126.4E: 085 (155): 040 (075): 994
+48: 10/0600: 12.8S 124.5E: 105 (190): 050 (095): 988
+60: 10/1800: 13.6S 122.9E: 120 (225): 055 (100): 985
+72: 11/0600: 14.7S 121.6E: 140 (255): 065 (120): 977
+96: 12/0600: 16.6S 119.7E: 165 (300): 080 (150): 963
+120: 13/0600: 19.5S 120.0E: 195 (365): 100 (185): 942
REMARKS:
Developing tropical low (23U) likely to become a severe tropical cyclone in
coming days.

Position based on visible imagery on the eastern edge of deep convection,
consistent with ongoing high easterly wind shear.

Earlier ASCAT showed 35kn under the deep convection west of the centre.
Intensity 35kn based on the ASCAT. Dvorak FT/CI=2.5, based on a D trend for
MET/PAT. Curved band with 0.5 wrap confirms 2.5.

Forecast track is based on a standard consensus of guidance. Steering is
dominated by a mid-level anti-cyclone to the southeast, apart from a brief
period of southerly motion in the short term due to stronger monsoon flow to
the north. This sees slow movement to the south in the short term, then faster
and to the west southwest starting Sunday then a turn to south on Wednesday. On
Thursday, an approaching upper trough could steer it faster and to the
southeast, but this could be after landfall.

The strong wind shear should constrain development in the short term but as the
system moves further south, then is expected to reduce. Forecast rate of
development is less than standard, increasing to standard from Monday morning.
This has it reaching category 1 at 1200 UTC Sunday, and a forecast intensity of
category 4 (100 kts) at landfall. Upper outflow could be favourable to very
favourable for a period and some sources of guidance indicate a higher
intensity is possible. Ocean temperatures in the area of forecast land fall are
very at the moment.

Copyright Commonwealth of Australia

[cycloneye]

TROPICAL CYCLONE ADVICE NUMBER 3
Issued at 8:38 pm WST on Saturday 8 April 2023

Headline:
Tropical low to develop into a tropical cyclone later Sunday with gales possible along the northwestern Kimberley coast. Potential severe tropical cyclone impact for east Pilbara or west Kimberley coast mid-next week.

Areas Affected:
Warning Zone
None.

Watch Zone
Kalumburu to Cockatoo Island, including Kalumburu.

Cancelled Zone
None.

Details of Tropical Low at 8:00 pm AWST:
Intensity: Tropical Low, sustained winds near the centre of 65 kilometres per hour with wind gusts to 95 kilometres per hour.

Location: within 55 kilometres of 10.3 degrees South 129.0 degrees East, estimated to be 315 kilometres northwest of Darwin and 515 kilometres north northeast of Kalumburu.

Movement: southwest at 9 kilometres per hour.

The low is likely to develop into a tropical cyclone later on Sunday as it tracks to the west southwest. It is expected to intensify further over following days as it moves along a general track parallel to the Kimberley coast.

There is a significant risk that this system will become a severe tropical cyclone and impacts the central or eastern Pilbara or western Kimberley coast from Wednesday.

Hazards:
Gales with wind gusts to 90 km/h and heavy rainfall could develop later Sunday or during Monday between Kalumburu and Cockatoo Island, including near Kalumburu. Squally thunderstorms with heavy falls are expected to develop in the far northern Kimberley during Sunday.

Recommended Action:
DFES advises of the following community alerts effective as of 2000 8th April 2023

A Cyclone Advice is current for people between Kalumburu and Cockatoo Island in the Shire of Wyndham-East Kimberley and the Shire of Derby-West Kimberley.

If you live in communities between Kalumburu and Cockatoo Island you need to prepare your home and family for a possible cyclone, with the development of a Tropical Low off the Western Australian coast.

Communities along the North Kimberley and West Kimberley Coast should start to prepare and monitor conditions and warnings.

[Hurricane2022]

[cycloneye]

[Landy]

JTWC's first forecast is incredibly bullish, forecasting a C5 on day 4 and a remarkable 50kt/24hr intensification rate at one point.

[Hurricane2022]

JTWC's first forecast is incredibly bullish, forecasting a C5 on day 4 and a remarkable 50kt/24hr intensification rate at one point.

https://media.discordapp.net/attachments/857017650042503178/1094345950790701196/sh182023.png

Jesus Christ!
First time I see the JTWC forecasting a Category 5 at Warning 1!!

[Category5Kaiju]

JTWC's first forecast is incredibly bullish, forecasting a C5 on day 4 and a remarkable 50kt/24hr intensification rate at one point.

https://media.discordapp.net/attachments/857017650042503178/1094345950790701196/sh182023.png

Yo, my goodness

Looks like there really is the potential for the strongest cyclone in this region since Marcus in 2018

[Hurricane2022]

The next name of the list is Ilsa.

[InfernoFlameCat]

JTWC's first forecast is incredibly bullish, forecasting a C5 on day 4 and a remarkable 50kt/24hr intensification rate at one point.

https://media.discordapp.net/attachments/857017650042503178/1094345950790701196/sh182023.png

That might be a bit conservative actually. This storm has insane potential!

[Iceresistance]

JTWC's first forecast is incredibly bullish, forecasting a C5 on day 4 and a remarkable 50kt/24hr intensification rate at one point.

https://media.discordapp.net/attachments/857017650042503178/1094345950790701196/sh182023.png

This storm has an extremely high ceiling