WTIO30 FMEE 280629
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 5/15/20202021
1.A TROPICAL DEPRESSION 15

2.A POSITION 2021/03/28 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 11.5 S / 68.3 E
(ELEVEN DECIMAL FIVE DEGREES SOUTH AND
SIXTY EIGHT DECIMAL THREE DEGREES EAST)
MOVEMENT: EAST 8 KT

3.A DVORAK ANALYSIS: 2.5/2.5/D 0.5/24 H

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

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 110 SW: 130 NW: 150

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/03/28 18 UTC: 10.9 S / 69.2 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 10 SE: 30 SW: 30 NW: 55

24H: 2021/03/29 06 UTC: 9.9 S / 70.4 E, VENT MAX= 025 KT, FILLING UP

36H: 2021/03/29 18 UTC: 9.3 S / 71.3 E, VENT MAX= 025 KT, FILLING UP

48H: 2021/03/30 06 UTC: 8.8 S / 71.9 E, VENT MAX= 020 KT, REMNANT LOW

60H: 2021/03/30 18 UTC: 8.4 S / 72.2 E, VENT MAX= 020 KT, REMNANT LOW

72H: 2021/03/31 06 UTC: 8.0 S / 71.8 E, VENT MAX= 020 KT, REMNANT LOW

2.B LONGER-RANGE OUTLOOK:
NIL


2.C ADDITIONAL INFORMATION:
FT=CI=2.5

OVER THE LAST SIX HOURS, THE SYSTEM'S CLOUD PATTERN HAS EVOLVED
TOWARDS A SHEARED PATTERN, WITH A LARGE AREA OF DEEP CONVECTION
DISPLACED TO THE SOUTHWEST OF THE LOW LEVEL CENTER. HOWEVER, THE LAST
INFRARED IMAGES HAVE SHOWN WARMING CLOUD TOPS. THIS MORNING'S ASCAT
SWATHS CONFIRM THE PRESENCE OF NEAR-GALE FORCE WINDS AND DON'T EXCEED
30KT. A GMI MICROWAVE PASS AT 0032Z SHOWS A RATHER WELL ORGANIZED
LOW-LEVEL VORTEX. THE SYSTEM'S INTENSITY IS THUS KEPT AT 30KT.

THE CURRENT AND FORECAST ENVIRONMENTAL CONDITIONS FOR THE NEXT FEW
DAYS ARE GETTING MORE AND MORE UNFAVORABLE : LOW LEVEL CONVERGENCE IS
STILL QUITE GOOD TODAY ON THE NORTHERN AND SOUTHERN SIDES OF THE
SYSTEM BUT IT WILL BECOME LESS FAVORABLE FROM MONDAY, AS
STRENGTHENING EQUATORIAL WESTERLIES WILL NOT FEED THE CIRCULATION
DIRECTLY. EASTERLY SHEAR ON THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE SHOULD CONTINUE DURING THE NEXT FEW DAYS AND IS EVEN EXPECTED
TO STRENGTHEN FROM MONDAY ONWARDS WHILE THE SYSTEM WILL TRACK
NORTHEASTWARD, FAVORING MORE DRY AIR INTRUSION. THIS SHOULD LEAD TO A
GRADUAL WEAKENING OF THE SYSTEM. THE POTENTIAL FOR IT TO REACH
MODERATE TROPICAL STORM STAGE NOW LOOKS VERY LOW.

UNTIL TUESDAY, THE SYSTEM'S TRACK IS MAINLY DRIVEN BY THE DYNAMIC OF
THE NEAR-EQUATORIAL WESTERLY WIND SURGE WHILE THE SUBTROPICAL RIDGE
TO THE SOUTH REMAINS WEAK AND SHALLOW, BEFORE EXPECTED STRENGTHENING
BY MID-WEEK, WHICH WILL PROBABLY MAKE IT TURN WESTWARD FROM
WEDNESDAY. HOWEVER, WITH SIGNIFICANT DISPERSION REMAINING AROUND THIS
SCENARIO, UNCERTAINTY ABOUT THE FORECAST TRACK IS HIGHER THAN
AVERAGE.

THIS SYSTEM SHOULD HAVE NO IMPACT ON THE BASIN'S INHABITED LANDS
DURING THE NEXT 5 DAYS.
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