AXAU01 APRF 310112
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 0112 UTC 31/01/2021
Name: Tropical Low
Identifier: 12U
Data At: 0000 UTC
Latitude: 19.5S
Longitude: 123.0E
Location Accuracy: within 25 nm [45 km]
Movement Towards: southwest [221 deg]
Speed of Movement: 7 knots [13 km/h]
Maximum 10-Minute Wind: 20 knots [35 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: 1002 hPa
Radius of outermost closed isobar: 180 nm [335 km]
FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 31/0600: 19.9S 122.3E: 040 [080]: 025 [045]: 993
+12: 31/1200: 20.0S 121.5E: 055 [100]: 030 [055]: 993
+18: 31/1800: 20.0S 120.6E: 060 [115]: 035 [065]: 992
+24: 01/0000: 19.9S 119.8E: 070 [130]: 035 [065]: 990
+36: 01/1200: 20.1S 117.9E: 080 [150]: 045 [085]: 987
+48: 02/0000: 20.7S 116.0E: 100 [185]: 050 [095]: 982
+60: 02/1200: 21.2S 114.6E: 115 [210]: 060 [110]: 974
+72: 03/0000: 21.5S 113.7E: 125 [235]: 065 [120]: 970
+96: 04/0000: 22.0S 112.5E: 160 [300]: 070 [130]: 963
+120: 05/0000: 23.0S 111.8E: 190 [350]: 055 [100]: 974
REMARKS:
The centre of tropical low 12U remains over land, and was located using a combination of satellite imagery, surface observations, and Broome weather radar. Position is fair. The low continues to exhibit a well organised structure
with deep convection persisting near the centre and well developed outer banding. Satellite presentation is consistent with NWP analysis, and suggests the circulation extends near vertically through the troposphere. Satellite winds
suggest the core of the system is under light wind shear from the northeast. Movement remains to the southwest at about 7 knots.

A mid-level anticyclone to the southeast of the system has been steering it in a general southwest direction, and broadly this will continue for the next several
days. However, the intensity forecast [and hence the impacts] remain critically dependent on subtle changes in the steering pattern - whether the system adopts a slightly more west-southwesterly track and moves off the coast, or remains over land on a southwesterly track. 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 extant convection, the system could quickly develop and potentially reach category 3 intensity, and this scenario is reflected in the current official forecast track.

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: 31/0730 UTC.
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