AXAU01 APRF 041858
IDW27600
TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
at: 1857 UTC 04/03/2021

Name: Tropical Cyclone Marian
Identifier: 15U
Data At: 1800 UTC
Latitude: 22.4S
Longitude: 94.6E
Location Accuracy: within 30 nm [55 km]
Movement Towards: southeast [144 deg]
Speed of Movement: 8 knots [15 km/h]
Maximum 10-Minute Wind: 45 knots [85 km/h]
Maximum 3-Second Wind Gust: 65 knots [120 km/h]
Central Pressure: 986 hPa
Radius of 34-knot winds NE quadrant: 130 nm [240 km]
Radius of 34-knot winds SE quadrant: 110 nm [205 km]
Radius of 34-knot winds SW quadrant: 130 nm [240 km]
Radius of 34-knot winds NW quadrant: 110 nm [205 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:
Radius of Maximum Winds: 40 nm [75 km]
Dvorak Intensity Code: T3.0/3.0/S0.0/24HRS SST:S0.0/06HRS
Pressure of outermost isobar: 1005 hPa
Radius of outermost closed isobar: 300 nm [555 km]

FORECAST DATA
Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
[UTC] : degrees : nm [km]: knots[km/h]: hPa
+06: 05/0000: 23.2S 95.0E: 045 [085]: 045 [085]: 987
+12: 05/0600: 23.8S 95.3E: 055 [100]: 040 [075]: 989
+18: 05/1200: 24.5S 95.6E: 060 [110]: 040 [075]: 989
+24: 05/1800: 25.0S 95.7E: 065 [125]: 035 [065]: 989
+36: 06/0600: 26.0S 96.1E: 090 [165]: 035 [065]: 988
+48: 06/1800: 26.5S 96.4E: 120 [225]: 035 [065]: 987
+60: 07/0600: 27.0S 96.1E: 150 [275]: 030 [055]: 996
+72: 07/1800: 27.6S 95.3E: 195 [360]: 030 [055]: 996
+96: 08/1800: 29.2S 94.3E: 265 [495]: 030 [055]: 994
+120: 09/1800: 29.4S 91.9E: 380 [710]: 025 [045]: 999

REMARKS:
The focus of convection around Marian is now positioned in the southern and eastern quadrants over the past 6 hours. There is still good confidence in the position of the system due to a recent Scatterometry pass. Marian is currently over 24-25C sea surface temperatures, experiencing low shear and looped satellite imagery indicates good poleward outflow.

Dvorak analysis: DT=3.0 with curve band analysis ranging from 0.65-0.75. CET=3.0
based a steady trend. PAT yielded 3.0. FT/CI at 3.0. CIMSS and NESDIS ADT agree on CI=2.3 32 knot 1-min wind. SATCON is at 46 knots 1-min [1501 UTC]. The current intensity at 45 knots.

Over the next couple of days Marian will track south southeast under the influence of mid-latitude trough to the southwest. The system is forecast to maintain tropical cyclone intensity over the next 18-24 hours in a low shear environment, however SST's of 24-25C will prevent any further intensification.

During Friday Marian is expected to encounter a high shear environment whilst also being influenced by some dry air which will all act to weaken the system. Marian will likely struggle to maintain vertical structure and weaken below tropical cyclone intensity Friday night/Saturday morning however gales may still
continue into Sunday on the southern flank due to the interaction with ridge to the south.

Latest model guidance is consistent with maintaining the system at tropical cyclone intensity over the next 48 hours. The current forecast diverges from this guidance and follows a conceptual model that deteriorating environmental conditions during Friday [unfavourable SSTs, high shear and dry air] will ultimately weaken the system below cyclone intensity by Saturday morning.

Copyright Commonwealth of Australia
==
The next bulletin for this system will be issued by: 05/0130 UTC.
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