• Indian-S: STS Alicia 13

    From Weather Alert@21:1/175 to All on Sun Nov 15 16:52:00 2020
    WTIO30 FMEE 151211
    RSMC / TROPICAL CYCLONE CENTER / LA REUNION
    TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

    0.A WARNING NUMBER: 13/1/20202021
    1.A SEVERE TROPICAL STORM 1 (ALICIA)

    2.A POSITION 2020/11/15 AT 1200 UTC:
    WITHIN 20 NM RADIUS OF POINT 13.7 S / 73.6 E
    (THIRTEEN DECIMAL SEVEN DEGREES SOUTH AND
    SEVENTY THREE DECIMAL SIX DEGREES EAST)
    MOVEMENT: SOUTH-SOUTH-WEST 13 KT

    3.A DVORAK ANALYSIS: 4.0/4.0/D 0.5/12 H

    4.A CENTRAL PRESSURE: 982 HPA
    5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT
    RADIUS OF MAXIMUM WINDS (RMW): 37 KM

    6.A EXTENSION OF WIND BY QUADRANTS (KM):
    28 KT NE: 200 SE: 200 SW: 170 NW: 170
    34 KT NE: 150 SE: 150 SW: 110 NW: 130
    48 KT NE: 60 SE: 60 SW: 60 NW: 0


    7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1005 HPA / 600 KM
    8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

    1.B FORECASTS:
    12H: 2020/11/16 00 UTC: 15.1 S / 73.3 E, VENT MAX= 065 KT, TROPICAL
    CYCLONE
    24H: 2020/11/16 12 UTC: 16.3 S / 73.0 E, VENT MAX= 045 KT, MODERATE
    TROPICAL STORM
    36H: 2020/11/17 00 UTC: 17.1 S / 72.4 E, VENT MAX= 040 KT, MODERATE
    TROPICAL STORM
    48H: 2020/11/17 12 UTC: 18.0 S / 71.6 E, VENT MAX= 035 KT, MODERATE
    TROPICAL STORM
    60H: 2020/11/18 00 UTC: 19.2 S / 70.8 E, VENT MAX= 025 KT, FILLING UP
    72H: 2020/11/18 12 UTC: 20.0 S / 69.7 E, VENT MAX= 020 KT, REMNANT
    LOW

    2.B LONGER-RANGE OUTLOOK:
    NIL

    2.C ADDITIONAL INFORMATION:
    T=CI=4.0

    FOR ALMOST 6 HOURS, THE CLOUD PATTERN OF ALICIA IS A CENTRAL DENSE
    OVERCAST (CDO) PATTERN SHOWING A SLIGHT INTENSIFICATION COMPARED TO
    THE PREVIOUS WARNING. IN THE ABSENCE OF RECENT MICROWAVE DATA, THE
    LOCATION OF THE CENTER IS NOT OBVIOUS AND BY FOLLOWING THE DVORAK
    ANALYSIS OF THE CLOUD PATTERN, WE CAN ESTIMATE WINDS OF THE ORDER OF
    55KT.

    THE TRACK FORECAST DOES NOT EVOLVE MUCH: ALICIA MOVES SOUTH-SOUTHWEST
    THEN SOUTH WITH THE EASTWARD WEAKENING OF THE SUBTROPICAL RIDGE. THE
    NUMERICAL MODELS REMAIN IN GOOD AGREEMENT ON THIS GLOBAL TRACK
    DESPITE SOME DIFFERENCES ON THE SPEED OF DISPLACEMENT. FROM TUESDAY
    ON, THE MODELS AGREE A LITTLE MORE ON THE OPTION OF THE CAPTURE OF
    THE REMNANT LOW BY THE TRADE WINDS, LEAVING A SOUTHWESTWARD TRACK BY
    WEDNESDAY.

    THE ENVIRONMENTAL CONDITIONS ARE STARTING TO BE A LITTLE LESS
    FAVORABLE BUT ALICIA IS STILL BENEFITING FOR 12 HOURS FROM A RANGE OF INTENSIFICATION THAT SHOULD BRING IT TO THE STAGE OF A TROPICAL
    CYCLONE. UNDER THESE CONDITIONS, ALICIA GENERATES A VERY MARKED HIGH
    ALTITUDE FLOW WHICH INDUCES A STRONG NEFAST WIND SHEAR TO THE
    CYCLOGENESIS OF A SECOND SYSTEM LOCATED NORTH-WEST OF ALICIA. FROM
    MONDAY, CONDITIONS SHOULD BEGIN TO QUICKLY DETERIORATE WITH
    INSUFFICIENT SEA TEMPERATURES SOUTH OF 17S, A STRENGTHENING SHEAR
    CONSTRAINT, GRADUALLY ASSOCIATED TO MID-LEVEL DRY INTRUSIONS. THESE
    CONDITIONS ANNOUNCE A CLEAR WEAKENING OF THE INTENSITY OF ALICIA,
    WHICH AT THE 78-HOUR PERIOD WILL ONLY HAVE RESIDUAL CIRCULATION.=
    #
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