• Aust: TC Seroja 101800

    From Weather Alert@1:2320/105 to All on Sat Apr 10 18:25:00 2021
    AXAU01 APRF 101915
    IDW27600
    TROPICAL CYCLONE TECHNICAL BULLETIN: AUSTRALIA - WESTERN REGION
    Issued by AUSTRALIAN BUREAU OF METEOROLOGY TROPICAL CYCLONE WARNING CENTRE
    at: 1914 UTC 10/04/2021

    Name: Tropical Cyclone Seroja
    Identifier: 22U
    Data At: 1800 UTC
    Latitude: 22.4S
    Longitude: 109.6E
    Location Accuracy: within 30 nm [55 km]
    Movement Towards: southeast [140 deg]
    Speed of Movement: 13 knots [24 km/h]
    Maximum 10-Minute Wind: 60 knots [110 km/h]
    Maximum 3-Second Wind Gust: 85 knots [155 km/h]
    Central Pressure: 974 hPa
    Radius of 34-knot winds NE quadrant: 120 nm [220 km]
    Radius of 34-knot winds SE quadrant: 80 nm [150 km]
    Radius of 34-knot winds SW quadrant: 60 nm [110 km]
    Radius of 34-knot winds NW quadrant: 80 nm [150 km]
    Radius of 48-knot winds NE quadrant: 60 nm [110 km]
    Radius of 48-knot winds SE quadrant: 40 nm [75 km]
    Radius of 48-knot winds SW quadrant: 30 nm [55 km]
    Radius of 48-knot winds NW quadrant: 40 nm [75 km]
    Radius of 64-knot winds:
    Radius of Maximum Winds: 30 nm [55 km]
    Dvorak Intensity Code: T4.0/4.0/D0.5/24HRS STT:S0.0/06HRS
    Pressure of outermost isobar: 1000 hPa
    Radius of outermost closed isobar: 90 nm [165 km]

    FORECAST DATA
    Date/Time : Location : Loc. Accuracy: Max Wind : Central Pressure
    [UTC] : degrees : nm [km]: knots[km/h]: hPa
    +06: 11/0000: 23.7S 110.6E: 040 [075]: 065 [120]: 971
    +12: 11/0600: 25.4S 111.8E: 050 [095]: 065 [120]: 971
    +18: 11/1200: 27.2S 113.6E: 055 [105]: 060 [110]: 976
    +24: 11/1800: 29.4S 116.2E: 065 [120]: 050 [095]: 984
    +36: 12/0600: 33.8S 123.0E: 090 [165]: 030 [055]: 993
    +48: 12/1800: 38.1S 130.0E: 125 [235]: 030 [055]: 992
    +60: 13/0600: : : :
    +72: 13/1800: : : :
    +96: 14/1800: : : :
    +120: 15/1800: : : :

    REMARKS:
    Current position and motion is good based on a 1448Z ASCAT METOP-C pass and a 1707Z GMI microwave image. The microwave pass shows a band of deep convection in
    the north and east quadrants wrapping around to the western quadrants to almost fully enclose the system centre.

    Recent satellite imagery has shown a developing convective band with cooling cloud tops wrapping around the system centre, to give a curved band of 0.9 wrap and a DT of 4.0, including 0.5 addition for the cold cloud tops. MET is 4.0 based on a D- trend due to the cooling cloud tops, with no adjustment from the PAT. FT and CI remain at 4.0. ADT is 3.0 [CIMSS] and 3.4 [NESDIS] although both are using uniform scenes rather than curved band. SATCON at 1217 UTC was 60 knots [one minute mean]. Final intensity is raised to 60kt based on the improving Dvorak trend.

    TC Seroja is being steered towards the southeast by a mid-level high to the northeast and an approaching mid-latitude trough to the southwest and is expected to make landfall on the mid-west coast of Western Australia later today.

    CIMSS shear analysis at 15 UTC has eased to 15 knots easterly and is supported by the recent satellite imagery showing the convection wrapping around the eastern side, while lower shear is analysed immediately south of the system. The
    recent microwave images confirms the low level circulation has remained symmetrical, so Seroja is forecast to intensify a little in response to these improving conditions and the lower shear environment along the forecast track in
    the next 6-12 hours. It is forecast to reach Category 3 intensity for a period on Sunday, in particular due to the enhanced wind field expected to develop in the northeast quadrant as it accelerates towards the southeast.

    Seroja is forecast to weaken into a Category 2 system before crossing the coast,
    however a Category 3 impact cannot be ruled out, particularly if it follows a crossing in the Shark Bay area.

    Copyright Commonwealth of Australia
    ==
    The next bulletin for this system will be issued by: 11/0130 UTC.
    &&
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