• Aust: STC Marian 021800

    From Weather Alert@21:1/175 to All on Tue Mar 2 23:29:00 2021
    AXAU01 APRF 021802
    IDW27600
    TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
    Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
    at: 1801 UTC 02/03/2021

    Name: Severe Tropical Cyclone Marian
    Identifier: 15U
    Data At: 1800 UTC
    Latitude: 18.6S
    Longitude: 90.5E
    Location Accuracy: within 20 nm [35 km]
    Movement Towards: east [090 deg]
    Speed of Movement: 3 knots [5 km/h]
    Maximum 10-Minute Wind: 75 knots [140 km/h]
    Maximum 3-Second Wind Gust: 105 knots [195 km/h]
    Central Pressure: 962 hPa
    Radius of 34-knot winds NE quadrant: 110 nm [205 km]
    Radius of 34-knot winds SE quadrant: 170 nm [315 km]
    Radius of 34-knot winds SW quadrant: 140 nm [260 km]
    Radius of 34-knot winds NW quadrant: 110 nm [205 km]
    Radius of 48-knot winds NE quadrant: 90 nm [165 km]
    Radius of 48-knot winds SE quadrant: 90 nm [165 km]
    Radius of 48-knot winds SW quadrant: 80 nm [150 km]
    Radius of 48-knot winds NW quadrant: 50 nm [95 km]
    Radius of 64-knot winds:
    Radius of Maximum Winds: 30 nm [55 km]
    Dvorak Intensity Code: T4.0/4.5/W1.0/24HRS STT:W0.5/6HRS
    Pressure of outermost isobar: 1004 hPa
    Radius of outermost closed isobar: 230 nm [425 km]

    FORECAST DATA
    Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
    [UTC] : degrees : nm [km]: knots[km/h]: hPa
    +06: 03/0000: 18.7S 90.9E: 030 [060]: 070 [130]: 967
    +12: 03/0600: 19.0S 91.4E: 040 [075]: 065 [120]: 971
    +18: 03/1200: 19.5S 91.9E: 040 [080]: 060 [110]: 976
    +24: 03/1800: 19.9S 92.4E: 045 [085]: 060 [110]: 975
    +36: 04/0600: 20.9S 93.5E: 055 [100]: 050 [095]: 983
    +48: 04/1800: 22.3S 94.5E: 065 [125]: 050 [095]: 983
    +60: 05/0600: 23.8S 95.3E: 085 [155]: 050 [095]: 984
    +72: 05/1800: 25.1S 95.9E: 105 [195]: 045 [085]: 986
    +96: 06/1800: 27.6S 96.9E: 175 [320]: 040 [075]: 988
    +120: 07/1800: 29.6S 97.6E: 280 [515]: 030 [055]: 994

    REMARKS:
    Marian continues to maintain a clear eye in EIR imagery so confidence in the location is good. The cyclone has an irregular large eye and EIR imagery shows

    a warming in the surrounding temperatures. Recent microwave and scatterometer passes show strongest convection and winds in the eastern semicircle [SMAP pass at 1203UTC].

    The 1800 UTC Dvorak analysis was based on EIR eye pattern with OW surrounding temperature, WMG eye temp and DG coldest ring temp, giving DT = 4.0. A W 24h trend yields MET = 4.5 and PAT 4.0. FT = 4.0, based on DT. CI was held at 4.5. Latest ADT yield 100 knot and 95 knot 1-min intensity estimates, SATCON appears to have ceased. Intensity has been decreased to 75 knots.

    Marian currently is under a low shear environment with good equatorward and poleward outflow. The cyclone is in a moist environment but drier air has wrapped around the western and northern flanks. CIMSS wind shear at 02/1500 UTC was below 10 knots but is forecast to increase on Wednesday and Thursday as the upper trough approaches. Marian is likely to be slow moving to the east and then
    southeast over the next 24 hours but as the upper trough increases in amplitude Marian should begin a steady movement to the southeast. The cooler SSTs combined
    with increased wind shear and the drier surrounding environment mean the current weakening trend is likely to continue.

    Gale and storm radii were estimated from the 1203 UTC SMAP pass showing larger radii in the eastern quadrants. NWP guidance maintains a strong symmetric structure until Thursday, when extra-tropical characteristics appear with gales in southern sectors only.


    Copyright Commonwealth of Australia
    ==
    The next bulletin for this system will be issued by: 03/0130 UTC.
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