SIO: MITCHELL - Tropical Cyclone

[Subtrop]

98P INVEST 260129 0600 15.2S 137.1E SHEM 15 0

[cycloneye]

THE AREA OF CONVECTION (INVEST 98P) PREVIOUSLY LOCATED NEAR
15.2S 137.1E IS NOW LOCATED NEAR 15.5S 137.8E, APPROXIMATELY 107 NM
NORTHWEST OF MORNINGTON ISLAND. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) DEPICTS AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC)
OFF THE COAST IN THE GULF OF CARPENTARIA. THE CIRCULATION IS COVERED BY
LARGE AMOUNTS OF FLARING CONVECTION OVER ITS CENTER. ENVIRONMENTAL
ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT WITH MODERATE
VERTICAL WIND SHEAR (15-20KTS), VERY WARM SEA SURFACE TEMPERATURES (3031
C), AND MODERATE EQUATORWARD UPPER LEVEL OUTFLOW. THE ECMWF AND NAVGEM
DETERMINISTIC MODELS DO NOT DEVELOP 98P, HOWEVER GFS INDICATES QUICK
FORMATION. ENSEMBLE MODELS ARE IN MODERATE AGREEMENT THAT 98P WILL
DEVELOP. 98P IS DEPICTED TO TAKE A GENERALLY NORTHEASTWARD TRACK THROUGH
THE GULF OF CARPENTARIA OVER THE NEXT 24 TO 48 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 22 TO 27 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
REMAINS MEDIUM.

[Vince_and_Grace_fan]

After it moved across the northern part of Australia in the last days as a well-defined land depression, it looks that this low will turn into a tropical cyclone if it will go far enough from the coast.

[cycloneye]

THE AREA OF CONVECTION (INVEST 98P) PREVIOUSLY LOCATED NEAR
16.4S 126.7E IS NOW LOCATED NEAR 17.3S 124.4E, APPROXIMATELY 131 NM
EAST-NORTHEAST OF BROOME, AUSTRALIA. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) DEPICTS A SLOWLY CONSOLIDATING CIRCULATION WITH A
PARTIALLY EXPOSED LLCC, WITH INCREASING DEEP CONVECTIVE ACTIVITY ON
THE WESTERN SIDE FROM INTERACTION WITH COASTAL WATERS. ENVIRONMENTAL
ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT AT THIS TIME
WITH LOW VERTICAL WIND SHEAR (10-15KTS) AND GOOD OUTFLOW ALOFT. THE
CURRENT VORTICITY SIGNATURE AND SPEED OVER LAND OF THE CIRCULATION
FAVORS GLOBAL DETERMINISTIC MODEL DEPICTIONS WHICH ARE IN AGREEMENT ON
THE CIRCULATION TRACKING BRIEFLY OVER WATER AND QUICKLY CONSOLIDATING
ALONG THE AUSTRALIAN COAST OVER THE NEXT 48-72HOURS. GLOBAL ENSEMBLE
MEMBERS HOWEVER HAVE A SLIGHTLY DIFFERENT OUTLOOK WITH GEFS SHOWING A
MAJORITY OF MEMBERS TRACKING WEST INTO THE INDIAN OCEAN AND EPS SPLIT
BETWEEN HUGGING THE COAST AND SLOWLY INTENSIFYING OR FOLLOWING THE
GEFS LEAD AND TRACKING WEST. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.

[cycloneye]

Tropical Low 21U is expected to develop off the north Pilbara coast.

Area affected
Warning zone
None.

Watch zone
Onslow to De Grey, including Karratha, Port Hedland and Barrow Island.

Cancelled zone
None.

At 8:00 pm Australian Western Standard Time
At 8:00 pm AWST

Intensity
tropical low, sustained winds near the centre of 30 kilometres per hour with wind gusts to 85 kilometres per hour

Location
within 65 kilometres of 17.8 degrees South, 123.8 degrees East, 165 kilometres east of Broome and 610 kilometres east northeast of Port Hedland

Movement
west at 25 kilometres per hour

Tropical Low 21U is located over the western Kimberley and is moving to the west. It is expected to move offshore of the Kimberley coast during Friday. Once offshore, 21U is expected to develop over waters off the Pilbara coast during the weekend, reaching category 1 strength during Saturday.

Over the weekend, 21U is forecast to move in a general west southwest direction, remaining parallel to the Pilbara coast. From later Sunday or Monday, 21U is expected to begin weakening as it takes a more southerly track towards the far west Pilbara coast or northern Gascoyne coast.

[cycloneye]

THE AREA OF CONVECTION (INVEST 98P) PREVIOUSLY LOCATED NEAR 16.4S 126.7E
IS NOW LOCATED NEAR 17.8S 122.6E, APPROXIMATELY 24 NM EAST-NORTHEAST OF
BROOME, AUSTRALIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) AS
WELL AS A 051352Z METOP B 89V MICROWAVE IMAGE DEPICTS A CONSOLIDATING
CIRCULATION WITH A PARTIALLY EXPOSED LLCC, RADAR FROM BROOME, AUSTRALIA
SHOWS DEEP CONVECTIVE CELLS ON THE WESTERN PERIPHERY DISPLACED FROM THE
CIRCULATION CENTER AS IT TAKES A MORE COASTAL POSITION. A 051356Z ASCAT
PASS REVEALS ELEVATED WINDS (20-25 KTS) ALONG THE AUSTRALIAN COAST IVO
ADELE ISLAND THESE ARE VERIFIED BY SURFACE OBSERVATIONS ON ADELE ISLAND
AT 051700Z READING 21KT WITH GUSTS OF 30KT. ENVIRONMENTAL ANALYSIS
INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT AT THIS TIME WITH LOW
VERTICAL WIND SHEAR (10-15KTS), GOOD OUTFLOW ALOFT AND WARM COASTAL
WATERS (28-29C). GLOBAL DETERMINISTIC MODEL DEPICTIONS ARE IN AGREEMENT
ON THE CIRCULATION TRACKING BRIEFLY OVER WATER AND QUICKLY CONSOLIDATING
AND INTENSIFYING ALONG THE WESTERN AUSTRALIAN COAST OVER THE NEXT 12-
24HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25
KNOTS.MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.

[cycloneye]

[cycloneye]

Details of Tropical Low 21U at 5:00 pm AWST:

Intensity
Tropical Low, sustained winds near the centre of 55 kilometres per hour with wind gusts to 85 kilometres per hour.

Location
within 35 kilometres of 18.5 degrees South 120.4 degrees East, estimated to be 275 kilometres northeast of Port Hedland and 450 kilometres northeast of Karratha.

Movement
west southwest at 25 kilometres per hour.

Tropical Low 21U is located over water to the northeast of Port Hedland and is moving in a west southwest direction. It is forecast to develop into a tropical cyclone early Saturday morning.

21U will continue to move generally west southwest, remaining offshore initially before turning towards the southwest later on Saturday and tracking closer to the Pilbara coast.

21U is expected to intensify to category 2 strength by Saturday evening. There is a slight possibility that 21U may further intensify to category 3 overnight Saturday if it moves more slowly than forecast and remains over warm offshore waters.

On its current track, 21U is expected to make landfall over the western Pilbara coast late on Sunday.

[Subtrop]

FKAU03 ADRM 061258
TC ADVISORY
DTG: 20260206/1200Z
TCAC: DARWIN
TC: MITCHELL
ADVISORY NR: 2026/2
OBS PSN: 06/1200Z S1830 E12006
CB: WI 120NM OF TC CENTRE TOP FL600
MOV: WSW 11KT
INTST CHANGE: INTSF
C: 994HPA
MAX WIND: 35KT
FCST PSN +6HR: 06/1800 S1848 E11912
FCST MAX WIND +6HR: 40KT
FCST PSN +12HR: 07/0000 S1906 E11830
FCST MAX WIND +12HR: 45KT
FCST PSN +18HR: 07/0600 S1930 E11742
FCST MAX WIND +18HR: 55KT
FCST PSN +24HR: 07/1200 S1954 E11700
FCST MAX WIND +24HR: 60KT
RMK: NIL
NXT MSG: 20260206/1900Z

[cycloneye]

[sasha_B]

Mitchell's IR presentation is a clear-cut T3.5, verging on T4.0. I concur with the JTWC's estimated Vmax of 60 kt (1-minute sustained). Aus. BoM has 57 kt, 982 hPa, for the same 0z track point, after applying the standard conversion factor. Central pressure estimates will of course vary according to where a given agency or forecaster places the outermost closed isobar; anywhere from 978 to 984 hPa would be reasonable for a 60-kt storm at this latitude, so again, the JTWC seems to me closer to the mark.

There's little reason not to expect this to make landfall as a Category 1-equivalent storm; whether it meets, exceeds, or falls short of the JTWC's forecast peak of 80 kts depends on how much time it has before landfall.

(ADT is lagging behind, but the past 12 hours of MW imagery plainly justify a 60 kt intensity estimate.)

[cycloneye]

Developing an eye feature.