WTIO30 FMEE 131828
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 41/13/20202021
1.A TROPICAL CYCLONE 13 (HABANA)

2.A POSITION 2021/03/13 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 21.5 S / 70.1 E
(TWENTY ONE DECIMAL FIVE DEGREES SOUTH AND
SEVENTY DECIMAL ONE DEGREES EAST)
MOVEMENT: SOUTH-SOUTH-WEST 4 KT

3.A DVORAK ANALYSIS: 4.0/4.5/W 0.5/6 H

4.A CENTRAL PRESSURE: 968 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 70 KT
RADIUS OF MAXIMUM WINDS (RMW): 46 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 205 SE: 295 SW: 260 NW: 205
34 KT NE: 165 SE: 205 SW: 205 NW: 150
48 KT NE: 110 SE: 155 SW: 160 NW: 110
64 KT NE: 75 SE: 85 SW: 85 NW: 75

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/03/14 06 UTC: 21.6 S / 70.3 E, VENT MAX= 055 KT, SEVERE
TROPICAL STORM
28 KT NE: 205 SE: 280 SW: 295 NW: 175
34 KT NE: 150 SE: 195 SW: 185 NW: 120
48 KT NE: 95 SE: 75 SW: 95 NW: 75

24H: 2021/03/14 18 UTC: 21.6 S / 70.5 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 195 SE: 305 SW: 285 NW: 155
34 KT NE: 150 SE: 205 SW: 185 NW: 95

36H: 2021/03/15 06 UTC: 21.3 S / 70.1 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 270 SW: 285 NW: 110
34 KT NE: 85 SE: 185 SW: 175 NW: 95

48H: 2021/03/15 18 UTC: 20.9 S / 68.9 E, VENT MAX= 035 KT, FILLING UP
28 KT NE: 95 SE: 240 SW: 295 NW: 65
34 KT NE: 85 SE: 165 SW: 155 NW: 35

60H: 2021/03/16 06 UTC: 20.7 S / 67.3 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 45 SE: 100 SW: 110 NW: 55

72H: 2021/03/16 18 UTC: 20.8 S / 65.8 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 45 SE: 150 SW: 130 NW: 55

2.B LONGER-RANGE OUTLOOK:
96H: 2021/03/17 18 UTC: 20.9 S / 63.1 E, VENT MAX= 025 KT, REMNANT
LOW


2.C ADDITIONAL INFORMATION:
T=4.0+ CI=4.5

DURING THE LAST SIX HOURS, THE CENTRAL DENSE OVERCAST PATTERN HAS
CONTINUED, WITH FLUCTUATING CLOUD TOPS. LITTLE OR NO MICROWAVE AND SCATTEROMETER DATA TO ASSIST IN THE ANALYSIS OF HABANA. THE SSMI-S
PASS OF 1351UTC SHOWED GOOD RESISTANCE OF THE CIRCULATION TO TILTING,
DESPITE SHEAR CONDITIONS BECOMING INCREASINGLY UNFAVORABLE
(WEST-NORTHWEST SHEAR) IN THE SOUTHERN SECTOR AND WITH THE ARRIVAL OF
DRY AIR IN THE WESTERN AND NORTHERN SECTOR OF HABANA. THE CLOUD
PATTERN OF HABANA REFLECTS WELL THESE CONDITIONS AND A DVORAK
ANALYSIS OF 4.0+ CAN BE MADE, LEAVING BY INERTIA A CI OF 4.5.
THEREFORE, WINDS OF 70KT CAN BE ESTIMATED, LEAVING HABANA STILL IN
THE TROPICAL CYCLONE STAGE BUT ON THE DECLINE.

IN TERMS OF TRACK, NO CHANGE IN THE RSMC FORECAST: HABANA IS MOVING
SLOWLY SOUTHWARD ALONG THE WESTERN EDGE OF THE SUBTROPICAL RIDGE IN
THE WEAKNESS GENERATED BY THE PASSAGE OF A TROUGH FURTHER SOUTH. THE
SYSTEM WILL STRONGLY SLOW DOWN ITS MOVEMENT IN THE NEXT FEW HOURS
UNDER THE INFLUENCE OF VERY WEAK AND CONTRADICTORY DIRECTING FLOWS,
LEADING TO A QUASI-STATIONNARY MOVEMENT (SLOW EASTWARDS DRIFT
EXPECTED). FROM MONDAY, MOST NWP MODELS AGREE ABOUT A NORTHWESTWARDS
AND THEN WESTWARDS TRACK, UNDER THE STEERING INFLUENCE OF A BUILDING
LOW TO MID TROPOSPHERE SUBTROPICAL RIDGE TO ITS SOUTH-WEST. THE
SYSTEM, WHICH SHOULD THEN BE IN THE PROCESS OF FILLING, WILL THEN
MOVE IN GENERALLY WESTWARDS ON THE NORTHERN EDGE OF THIS RIDGE.
RSMC'S FORECAST IS BASED ON A COMPROMISE BETWEEN THE BEST AVAILABLE
GUIDANCE.

IN TERMS OF INTENSITY FORECAST, THE PREVIOUS FORECAST IS REVISED
DOWNWARDS. THE ENVIRONMENTAL CONDITIONS ARE REALLY NOT OPTIMAL
ANYMORE AND WILL BECOME MORE AND MORE UNFAVORABLE IN THE NEXT HOURS
WITH A WELL ESTABLISHED MID-TROPOSPHERE SHEAR, BRINGING DRY AIR
GRADUALLY TO THE CORE OF THE SYSTEM. MOREOVER, ITS WEAK DISPLACEMENT
WILL LEAVE A VERY LIMITED OCEANIC POTENTIAL BRINGING AN ADDITIONAL
CONDITION TO THE RAPID WEAKENING OF HABANA. ON MONDAY, AS IT RESUMES
ITS OVERALL WESTWARD MOTION, HABANA WILL ALREADY BE IN THE VERY
WEAKENED STAGE OF A MODERATE TROPICAL STORM AND WILL CONTINUE TO
EVOLVE INTO A FILLING DEPRESSION AND THEN A REMNANT LOW.

FROM NEXT TUESDAY, THE REMNANT LOW OF HABANA SHOULD APPROACH THE
RODRIGUES ISLAND WITHOUT ANY PARTICULAR CONSEQUENCE IN TERMS OF WINDS
OR RAIN. EASTERLY SWELL GENERATED BY HABANA HAS ALREADY PROPAGATED TO
THE MASCAREIGNES ISLANDS AND WILL LAST DURING THE FIRST PART OF NEXT
WEEK.
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