• Indian-S: TS Habana W5

    From Weather Alert@21:1/175 to All on Thu Mar 4 16:39:00 2021
    WTIO30 FMEE 041909
    RSMC / TROPICAL CYCLONE CENTER / LA REUNION
    TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

    0.A WARNING NUMBER: 5/13/20202021
    1.A MODERATE TROPICAL STORM 13 (HABANA)

    2.A POSITION 2021/03/04 AT 1800 UTC:
    WITHIN 20 NM RADIUS OF POINT 16.6 S / 73.7 E
    (SIXTEEN DECIMAL SIX DEGREES SOUTH AND
    SEVENTY THREE DECIMAL SEVEN DEGREES EAST)
    MOVEMENT: EAST-SOUTH-EAST 11 KT

    3.A DVORAK ANALYSIS: 3.0/3.0/D 1.5/24 H

    4.A CENTRAL PRESSURE: 992 HPA
    5.A MAX AVERAGE WIND SPEED (10 MN): 45 KT
    RADIUS OF MAXIMUM WINDS (RMW): 26 KM

    6.A EXTENSION OF WIND BY QUADRANTS (KM):
    28 KT NE: 280 SE: 185 SW: 95 NW: 185
    34 KT NE: 110 SE: 75 SW: 55 NW: 95

    7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 700 KM
    8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

    1.B FORECASTS (WINDS RADII IN KM):
    12H: 2021/03/05 06 UTC: 16.5 S / 75.3 E, VENT MAX= 050 KT, SEVERE
    TROPICAL STORM
    28 KT NE: 155 SE: 150 SW: 150 NW: 110
    34 KT NE: 95 SE: 140 SW: 85 NW: 65
    48 KT NE: 55 SE: 0 SW: 0 NW: 35

    24H: 2021/03/05 18 UTC: 16.0 S / 76.6 E, VENT MAX= 045 KT, MODERATE
    TROPICAL STORM
    28 KT NE: 165 SE: 130 SW: 100 NW: 75
    34 KT NE: 100 SE: 120 SW: 55 NW: 65

    36H: 2021/03/06 06 UTC: 15.6 S / 77.4 E, VENT MAX= 035 KT, MODERATE
    TROPICAL STORM
    28 KT NE: 150 SE: 150 SW: 130 NW: 75
    34 KT NE: 85 SE: 85 SW: 85 NW: 65

    48H: 2021/03/06 18 UTC: 15.7 S / 78.6 E, VENT MAX= 030 KT, REMNANT
    LOW
    28 KT NE: 140 SE: 85 SW: 75 NW: 65

    60H: 2021/03/07 06 UTC: 15.9 S / 79.6 E, VENT MAX= 025 KT, REMNANT
    LOW

    72H: 2021/03/07 18 UTC: 16.3 S / 81.1 E, VENT MAX= 025 KT, REMNANT
    LOW

    2.B LONGER-RANGE OUTLOOK:
    96H: 2021/03/08 18 UTC: 17.1 S / 82.7 E, VENT MAX= 030 KT, TROPICAL
    DEPRESSION
    28 KT NE: 140 SE: 75 SW: 55 NW: 75

    120H: 2021/03/09 18 UTC: 17.7 S / 82.1 E, VENT MAX= 035 KT, MODERATE
    TROPICAL STORM
    28 KT NE: 165 SE: 100 SW: 100 NW: 65
    34 KT NE: 75 SE: 65 SW: 45 NW: 55

    2.C ADDITIONAL INFORMATION:
    T=CI=3.0+

    MICROWAVE IMAGES OF THE END OF THE DAY SHOWED THAT AN INNER-CORE
    BRIEFLY CONSTITUTED ITSELF AROUND 12Z BEFORE SHOWING SIGNS OF
    WEAKENING AROUND 15Z. A SMAP PASS AROUND 13Z SHOWED MAXIMUM WINDS AT
    47 KT. THE INTENSITY HAS RISEN TO 45 KT AS A COMPROMISE BETWEEN THE
    SMAP DATA AND THE SUBJECTIVE ESTIMATES AT 40 KT.

    OVER THE NEXT DAYS, HABANA SHOULD TRACK EAST-SOUTHEASTWARD DRIVEN BY
    THE NEAR EQUATORIAL RIDGE. A TEMPORARY EAST-NORTH-EASTWARD TURN IS
    SUGGESTED BY SOME GUIDANCES SATURDAY, AS THE RIDGE SHIFTS WESTWARDS
    THUS MODIFYING THE STEERING FLOW. EARLY NEXT WEEK, THE LOW SHOULD
    SLOW DOWN IN RELATION WITH THE WEAKENING OF THE NEAR EQUATORIAL
    RIDGE, BEFORE TURNING SOUTH-WESTWARD UNDER THE GROWING INFLUENCE OF
    THE SUBTROPICAL RIDGE.

    HABANA IS EXPECTED TO KEEP INTENSIFYING IN THE NEXT HOURS WHILE
    BENEFITING FROM CONDUCIVE CONDITIONS : EXCELLENT DIVERGENCE IN THE SOUTH-EASTERN QUADRANT AND VERY GOOD SURFACE CONVERGENCE ON THE
    EQUATORIAL SIDE. FRIDAY, ENVIRONMENTAL CONDITIONS SHOULD BEGIN TO
    DETERIORATE FIRST IN THE MID-LEVELS THEN IN THE UPPER LEVELS, WITH
    THE STRENGTHENING OF A WEST-NORTH-WESTERLY SHEAR AHEAD OF A DEEP
    UPPER TROUGH. AVAILABLE GUIDANCE SUGGEST AN INJECTION OF DRY AIR INTO
    THE SYSTEM'S INNER CORE SATURDAY, WHICH SHOULD LEAD TO A WEAKENING.
    AS THE SYSTEM WILL TRACK IN THE SAME DIRECTION AS THE SHEAR
    CONSTRAINT, IT COULD RESIST A LITTLE BIT LONGER THAN EXPECTED WHILE
    BENEFITING FROM A GOOD SOUTHEASTWARD DIVERGENCE, WHICH INTRODUCES A
    SIGNIFICANT UNCERTAINTY IN THE INTENSITY FORECAST.

    NEXT WEEK, THE UPPER SHEAR SHOULD ABATE AND THE AVAILABLE GUIDANCE
    SUGGEST A REAL POTENTIAL FOR REINTENSIFICATION. HOWEVER, THESE LONG
    TERM RE-INTENSIFICATIONS HAVE ESSENTIALLY BEEN FALSE ALARMS SINCE THE
    BEGINNING OF THE SEASON AND LOW CONFIDENCE IS GIVEN TO THIS SCENARIO.
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