• Indian-S: TD5 W4

    From Weather Alert@21:1/175 to All on Thu Dec 31 22:59:00 2020
    WTIO30 FMEE 311837
    RSMC / TROPICAL CYCLONE CENTER / LA REUNION
    TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

    0.A WARNING NUMBER: 4/5/20202021
    1.A TROPICAL DEPRESSION 5

    2.A POSITION 2020/12/31 AT 1800 UTC:
    WITHIN 20 NM RADIUS OF POINT 13.9 S / 83.4 E
    (THIRTEEN DECIMAL NINE DEGREES SOUTH AND
    EIGHTY THREE DECIMAL FOUR DEGREES EAST)
    MOVEMENT: WEST 5 KT

    3.A DVORAK ANALYSIS: 2.0/2.0/S 0.0/6 H

    4.A CENTRAL PRESSURE: 1000 HPA
    5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
    RADIUS OF MAXIMUM WINDS (RMW): 111 KM

    6.A EXTENSION OF WIND BY QUADRANTS (KM):
    28 KT NE: 0 SE: 110 SW: 220 NW: 220

    7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1007 HPA / 600 KM
    8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

    1.B FORECASTS (WINDS RADII IN KM):
    12H: 2021/01/01 06 UTC: 14.1 S / 82.3 E, VENT MAX= 030 KT, TROPICAL
    DEPRESSION
    28 KT NE: 10 SE: 55 SW: 130 NW: 55

    24H: 2021/01/01 18 UTC: 14.4 S / 80.5 E, VENT MAX= 030 KT, TROPICAL
    DEPRESSION
    28 KT NE: 10 SE: 75 SW: 110 NW: 55

    36H: 2021/01/02 06 UTC: 15.0 S / 78.6 E, VENT MAX= 035 KT, MODERATE
    TROPICAL STORM
    28 KT NE: 45 SE: 175 SW: 150 NW: 75
    34 KT NE: 35 SE: 55 SW: 75 NW: 65

    48H: 2021/01/02 18 UTC: 15.4 S / 77.0 E, VENT MAX= 035 KT, MODERATE
    TROPICAL STORM
    28 KT NE: 110 SE: 85 SW: 150 NW: 185
    34 KT NE: 100 SE: 20 SW: 45 NW: 130

    60H: 2021/01/03 06 UTC: 15.3 S / 75.8 E, VENT MAX= 030 KT,
    DISSIPATING
    28 KT NE: 140 SE: 130 SW: 130 NW: 140


    2.B LONGER-RANGE OUTLOOK:
    NIL


    2.C ADDITIONAL INFORMATION:

    OVER THE LAST 6 HRS, THE SAT PRESENTATION OF TROPICAL DEPRESSION 5
    DID NOT EVOLVE MUCH : CONVECTION IS STILL REJECTED WITHIN THE WESTERN SEMI-CIRCLE UNDER THE INFLUENCE OF A STRONG EASTERLY SHEAR. THE
    LOW-LEVEL CIRCULATION STILL SEEMS TO BE RATHER ELONGATED. THE 1530Z
    ASCAT-A SWATH ONLY COVERS A PART OF THE WESTERN SEMI-CIRCLE BUT STILL
    CONFIRMS THE PRESENCE OF NEAR-GALE FORCE WINDS.

    THE TROPICAL DEPRESSION IS NOW MOVING SLOWLY IN A GENERAL WESTERLY
    DIRECTION ON THE NORTHERN SIDE OF THE SUBTROPICAL HIGH PRESSURE
    SYSTEM. THE SYSTEM WILL KEEP THIS WESTERLY TRAJECTORY UNTIL SATURDAY
    WITH A TENDENCY TO ACCELERATE. THEREAFTER, THE SYSTEM SHOULD INTERACT
    WITH THE SYSTEM 06 FURTHER WEST. IN THESE CONDITIONS, A FUJIWHARA
    EFFECT SHOULD OCCUR LEAVING A LARGE UNCERTAINTY IN THE TRACK FORECAST
    OF THE SYSTEM 05 FOR THE WEEKEND WITH A VERY FLUCTUATING TRACK IN
    DIRECTION AND SPEED (LOOP OR REVERSAL). THE REMAINING SYSTEM BORN
    FROM THE INTERACTION WITH SYSTEM 6 SHOULD THEN HEAD WESTWARD AGAIN ON
    THE NORTHERN SIDE OF A WIDE SUBTROPICAL RIDGE.

    THE SYSTEM REMAINS UNDERMINED BY A STRONG EASTERLY SHEAR UNTIL
    TOMORROW NIGHT. FROM SATURDAY, THE UPPER CONDITIONS BECOME MORE
    FAVORABLE TO THE DEVELOPMENT OF THE SYSTEM WITH EVEN AN INCREASING
    UPPER DIVERGENCE. HOWEVER, THE INTERACTION WITH SYSTEM 6 IN THE
    NORTH-WEST SHOULD SIGNIFICANTLY AFFECT THE LOW-LEVEL CONDITIONS. THE
    AVAILABLE GUIDANCE IS CURRENTLY STRUGGLING TO CHOOSE WHICH
    CIRCULATION WILL ABSORB THE OTHER. THE AVAILABLE MODELS HAVE CHANGED
    THEIR SCENARIO ON THE LAST TWO RUNS AND ARE NOW SUGGESTING THE
    PREVALENCE OF SYSTEM 6 OVER SYSTEM 5, AS THE LATTER UNDERCUTS THE
    EQUATORIAL LOW-LEVEL CONVERGENCE OF ITS RIVAL. FROM THE BEGINNING OF
    NEXT WEEK, THE REMAINING SYSTEM SHOULD BENEFIT FROM RATHER CONDUCIVE
    CONDITIONS FOR ITS DEVELOPMENT EVEN IF SOME MID-LEVEL DRY AIR IN THE
    SOUTH COULD LIMIT THE PACE OF INTENSIFICATION.

    SIMILAR TO THE FORECAST OF SYSTEM 06, THE CONFIDENCE IN TRACK AND
    INTENSITY REMAINS LOW, AS THE TWO SYSTEMS ARE EXPECTED TO INTERACT
    WITH EACH OTHER. ONE OF THE TWO SHOULD EVENTUALLY DOMINATE THE OTHER
    BUT IS IS NOT IMPOSSIBLE THAT BOTH SYSTEM INCAPACITATE EACH OTHER.
    =
    --- SBBSecho 3.12-Linux
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (21:1/175)