WTIO30 FMEE 070721
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 12/14/20202021
1.A MODERATE TROPICAL STORM 14 (IMAN)

2.A POSITION 2021/03/07 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 22.7 S / 54.8 E
(TWENTY TWO DECIMAL SEVEN DEGREES SOUTH AND
FIFTY FOUR DECIMAL EIGHT DEGREES EAST)
MOVEMENT: EAST 9 KT

3.A DVORAK ANALYSIS: 2.0/2.5/W 0.5/6 H

4.A CENTRAL PRESSURE: 996 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 240 SE: 370 SW: 130 NW: 130
34 KT NE: 0 SE: 280 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1005 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/03/07 18 UTC: 23.7 S / 57.1 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 195 SE: 140 SW: 85 NW: 130
34 KT NE: 100 SE: 100 SW: 75 NW: 35

24H: 2021/03/08 06 UTC: 25.0 S / 59.4 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 305 SE: 220 SW: 100 NW: 100
34 KT NE: 165 SE: 165 SW: 85 NW: 75

36H: 2021/03/08 18 UTC: 27.3 S / 61.0 E, VENT MAX= 040 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 205 SE: 215 SW: 150 NW: 110
34 KT NE: 95 SE: 165 SW: 130 NW: 45

48H: 2021/03/09 06 UTC: 29.4 S / 62.1 E, VENT MAX= 040 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 185 SE: 270 SW: 75 NW: 85
34 KT NE: 85 SE: 205 SW: 65 NW: 35

60H: 2021/03/09 18 UTC: 31.3 S / 62.8 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 220 SE: 140 SW: 75 NW: 55
34 KT NE: 85 SE: 130 SW: 65 NW: 35

72H: 2021/03/10 06 UTC: 32.7 S / 63.4 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 185 SE: 95 SW: 155 NW: 110
34 KT NE: 55 SE: 85 SW: 110 NW: 35

2.B LONGER-RANGE OUTLOOK:
96H: 2021/03/11 06 UTC: 34.6 S / 65.0 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 95 SE: 140 SW: 95 NW: 35

120H: 2021/03/12 06 UTC: 35.9 S / 66.4 E, VENT MAX= 025 KT, REMNANT
LOW

2.C ADDITIONAL INFORMATION:
FT=2.0 CI=2.5+

FIRST DAYLIGHT VISIBLE IMAGES SHOWED THAT THE CENTER WAS LOCATED A
BIT WEST OF THE INITIAL ANALYSIS. IT IS NOW ON THE EDGE OF THE
CONVECTIVE ACTIVITY BECAUSE OF A NORTH-WESTERLY SHEAR (15/20KT
ACCORDING TO CIMSS). LAST SATELLITES IMAGES SUGGEST THE IMMINENT
BEGINNING OF THE EXTRATROPICAL TRANSITION WITH AN INCREASINGLY
ELONGATED LOW LEVEL CIRCULATION.

THE SYSTEM SHOULD CONTINUE TRACKING SOUTH-EASTWARDS AHEAD OF A
MID-LATITUDES TROUGH. EARLY NEXT WEEK, THE SYSTEM SHOULD BE CAPTURED
BY A MID-LATITUDES TROUGH WHICH SHOULD BRING IT SOUTH OF 25S, FAR
FROM THE INHABITED ISLANDS, ALONG A SOUTH-EASTWARDS THEN
SOUTH-SOUTH-EASTWARDS TRACK. AT THE END OF THE TAUS, THE RESIDUAL
DEPRESSION MIGHT BE TEMPORARILY SLOWED DOWN BY THE ARRIVAL OF A NEW
ANTICYCLONE FROM THE WEST.

IN THE NEXT HOURS BECAUSE OF THE STRONGER SHEAR AND THE INCREASINGLY
BAROCLINIC ENVIRONMENT, THE LOW IS EXPECTED TO START ITS
EXTRATROPICAL TRANSITION. WHILE INTERACTING WITH THE UPPER TROUGH,
GALE FORCE WINDS MAY PERSIST.

IN TERMS OF IMPACT FOR THE MASCARENES, AFTER HITTING REUNION ISLAND,
A STRONG CONVECTIVE SQUALL LINE IS MOVING TOWARDS MAURITIUS.
TOMORROW, IMAN SHOULD NOT HAVE A MAJOR INFLUENCE ON THE INHABITED
ISLANDS ANYMORE.
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