AXAU01 APRF 311310
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1310 UTC 31/01/2021
Name: Tropical Low
Identifier: 12U
Data At: 1200 UTC
Latitude: 20.6S
Longitude: 121.7E
Location Accuracy: within 25 nm [45 km]
Movement Towards: west southwest [240 deg]
Speed of Movement: 7 knots [13 km/h]
Maximum 10-Minute Wind: 25 knots [45 km/h]
Maximum 3-Second Wind Gust: 45 knots [85 km/h]
Central Pressure: 994 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: N/A overland
Pressure of outermost isobar: 998 hPa
Radius of outermost closed isobar: 80 nm [150 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 31/1800: 20.6S 120.7E: 040 [080]: 025 [045]: 994
+12: 01/0000: 20.6S 119.7E: 055 [100]: 030 [055]: 993
+18: 01/0600: 20.6S 118.8E: 060 [115]: 030 [055]: 993
+24: 01/1200: 20.7S 117.8E: 070 [130]: 035 [065]: 990
+36: 02/0000: 21.0S 115.9E: 080 [150]: 040 [075]: 986
+48: 02/1200: 21.5S 114.4E: 100 [185]: 045 [085]: 982
+60: 03/0000: 21.9S 113.3E: 115 [210]: 050 [095]: 977
+72: 03/1200: 22.0S 112.4E: 125 [235]: 055 [100]: 973
+96: 04/1200: 22.4S 111.3E: 160 [300]: 055 [100]: 972
+120: 05/1200: 23.5S 111.2E: 190 [350]: 050 [095]: 976
REMARKS:
The centre of tropical low 12U remains over land, and was located using a combination of satellite imagery and surface observations. Position is fair.
he
low continues to exhibit a reasonably well organised structure with deep convection persisting near the centre and well developed outer banding. Based
n
the surface analysis position, the deep convection is becoming more displaced
o
the southwest, in response to increasing northeasterly shear. Recent movement
s
WSW at 7 knots.

A mid-level anticyclone to the southeast of the system has been steering it in

general southwest direction, and broadly this will continue for the next
everal
days. The observed and forecast steering to the west or west southwest is in response to the mid level ridge strengthening to the south of the system. With this motion being approximately parallel to the Pilbara cost, subtle changes in the steering pattern could see the system move offshore or remain over land.
he
intensity forecast [and impacts] is critically dependent on this. Guidance remains split on this topic with no significant trends either way.

Should the system move off the coast, the environment becomes favourable for development with SSTs greater than 30 degrees and decreasing NE'ly deep layer shear. Given the deep circulation and convection, the system could quickly develop and reach category 2 intensity, and this scenario is reflected in the current official forecast track. There remains a slight chance of the system reaching category 3 intensity if it moves further north and moves offshore sooner than forecast.

In the longer term, after 72 hours, a mid-level trough to the south is expected to weaken the steering ridge and slow the system down, before causing it to recurve to the south parallel to the west coast of WA.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 31/1930 UTC.
#
ealth o
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