WTIO30 FMEE 071841
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

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

2.A POSITION 2021/03/07 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 24.3 S / 57.9 E
(TWENTY FOUR DECIMAL THREE DEGREES SOUTH AND
FIFTY SEVEN DECIMAL NINE DEGREES EAST)
MOVEMENT: EAST-SOUTH-EAST 15 KT

3.A DVORAK ANALYSIS: 2.0/2.5/S 0.0/12 H

4.A CENTRAL PRESSURE: 997 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: 150 SE: 185 SW: 185 NW: 150
34 KT NE: 95 SE: 95 SW: 150 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1005 HPA / 900 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/03/08 06 UTC: 26.2 S / 60.3 E, VENT MAX= 040 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 215 SE: 205 SW: 165 NW: 150
34 KT NE: 130 SE: 150 SW: 130 NW: 35

24H: 2021/03/08 18 UTC: 28.1 S / 62.2 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 175 SE: 140 SW: 100 NW: 130
34 KT NE: 100 SE: 110 SW: 95 NW: 45

36H: 2021/03/09 06 UTC: 30.5 S / 63.7 E, VENT MAX= 035 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 185 SE: 140 SW: 165 NW: 130
34 KT NE: 95 SE: 130 SW: 150 NW: 55

48H: 2021/03/09 18 UTC: 32.0 S / 64.1 E, VENT MAX= 030 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 195 SE: 140 SW: 95 NW: 215

60H: 2021/03/10 06 UTC: 32.9 S / 64.4 E, VENT MAX= 025 KT, FILLING UP

72H: 2021/03/10 18 UTC: 33.2 S / 64.6 E, VENT MAX= 025 KT, FILLING UP

2.B LONGER-RANGE OUTLOOK:
NIL


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

DURING THE LAST SIX HOURS, THE CLOUD CONFIGURATION HAS LOST ITS
CURVED BAND STRUCTURE AND EVOLVES INTO A CDO PATTERN AS SEEN IN THE
INFRA-RED IMAGES. HOWEVER, DVORAK CONSTRAINTS STILL LEAVE A
POSSIBILITY OF ANALYSIS AT THE THRESHOLD OF MODERATE TROPICAL STORMS,
OR EVEN TROPICAL DEPRESSION. HOWEVER IMAN LOSES MORE AND MORE ITS
PURELY TROPICAL STRUCTURE AND IT IS THE 1608UTC ASCENT PASS THAT
ALLOWS TO DEFINE WINDS OF THE ORDER OF 35KT, WITH A MORE ELONGATED
STRUCTURE.

NO CHANGE IN THE FORECAST CHOSEN BY THE RSMC. THE SYSTEM CONTINUES
ITS TRACK TOWARDS THE SOUTHEAST IN FRONT OF THE TROUGH THAT RUNS
FURTHER SOUTH AND WHICH SHOULD CAPTURE IMAN EVACUATING IT SOUTH OF
25S. AFTER A MORE SOUTHERLY TRACK FROM TUESDAY, IT WILL BE SLOWED
DOWN AND THEN BLOCKED BY THE ARRIVAL OF A NEW HIGH PRESSURE FROM THE
WEST, LEAVING IT IN A REMNANT LOW BY THURSDAY.

THE PURE TROPICAL STRUCTURE OF IMAN BEGINS TO DISAPPEAR AND UNDER THE
EFFECT OF WIND SHEAR, IN A PREDOMINANTLY BAROCLINIC CONTEXT, IMAN
EVOLVES INTO A POST-TROPICAL SYSTEM. BY INTERACTION WITH THE HIGH
ALTITUDE TROUGH, IMAN COULD MAINTAIN OR EVEN INTENSIFY THESE WINDS AT
THE THRESHOLD OF 40/45KT, DURING THE NEXT 12/18 HOURS. THEREAFTER
UNDER THE EFFECT OF WINDSHEAR AND DRY AIR, IMAN WILL GRADUALLY WEAKEN
AT THE THRESHOLD OF REMNANT LOW.

AS OF TONIGHT, IMAN NO LONGER POSES A MENACE TO THE INHABITED LANDS
OF THE MASCARENE ISLANDS.
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