WTIO30 FMEE 271212
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 1/9/20202021
1.A TROPICAL DEPRESSION 9

2.A POSITION 2021/01/27 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 19.6 S / 90.4 E
(NINETEEN DECIMAL SIX DEGREES SOUTH AND
NINETY DECIMAL FOUR DEGREES EAST)
MOVEMENT: WEST 10 KT

3.A DVORAK ANALYSIS: 2.5/2.5/S 0.0/0 H

4.A CENTRAL PRESSURE: 1001 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: 165 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/01/28 00 UTC: 19.4 S / 87.5 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 95 NW: 0

24H: 2021/01/28 12 UTC: 19.0 S / 83.8 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 95 NW: 0

36H: 2021/01/29 00 UTC: 18.1 S / 80.1 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 165 NW: 0

48H: 2021/01/29 12 UTC: 17.6 S / 76.7 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 165 NW: 0

60H: 2021/01/30 00 UTC: 17.1 S / 73.2 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 0 SE: 165 SW: 165 NW: 0

72H: 2021/01/30 12 UTC: 16.7 S / 70.1 E, VENT MAX= 025 KT, TROPICAL
DISTURBANCE

2.B LONGER-RANGE OUTLOOK:
96H: 2021/01/31 12 UTC: 15.7 S / 64.1 E, VENT MAX= 020 KT, TROPICAL
DISTURBANCE

120H: 2021/02/01 12 UTC: 15.0 S / 58.7 E, VENT MAX= 020 KT, FILLING
UP

2.C ADDITIONAL INFORMATION:
T=CI=2.5-

INITIALLY FOLLOWED BY THE BOM VIA SPECIFIC BULLETINS AND THEN THROUGH
THE TROPICAL CYCLONE OUTLOOK BULLETIN (IDW10800) FOLLOWING ITS
WEAKENING, TROPICAL DEPRESSION WILL ENTER THE ZONE OF RESPONSIBILITY
OF THE RSMC LA REUNION IN THE COMING HOURS. THIS SYSTEM DEFINES THE
SYSTEM NUMBER 09 OF OUR BASIN. THE CLOUD CONFIGURATION IS A SHEARED CONFIGURATION WHOSE CONVECTIVE ACTIVITY IS LOCATED IN THE SOUTHEAST
QUADRANT WITH RESPECT TO THE CIRCULATION CENTER. THE CENTER OF LOW
LEVELS IS ALSO DETECTABLE ON THE VISIBLE SATELLITE IMAGES. IN THIS CONFIGURATION, A DVORAK ANALYSIS CAN BE DONE AT 2.5- GIVING A WIND
ESTIMATE OF AROUND 30KT. THIS ESTIMATE IS VALIDATED BY THE PARTIAL
ASCAT SWATH OF 0320UTC WHERE THE 30KT WINDS ARE ONLY LOCATED IN THE
SOUTHEAST QUADRANT OF THE CIRCULATION. THE 09 SYSTEM IS IN AN
ENVIRONMENT UNFAVORABLE TO INTENSIFICATION WITH DRY AIR PRESENT AT
HIGH ALTITUDE (MAINLY IN THE WESTERN AND NORTHERN SECTOR). A STRONG
NORTH WIND SHEAR IS ALSO PRESENT AT THE WESTERN EDGE OF THE SYSTEM
CONTRIBUTING A LITTLE MORE TO LOCALIZE THE CONVECTION ONLY IN THE
SOUTHEAST QUADRANT.

IN TERMS OF TRACK FORECAST, THE 09 SYSTEM IS UNDER THE INFLUENCE OF
THE SUBTROPICAL RIDGE WHICH IS LOCATED IN THE SOUTHEAST OF THE BASIN
AND WHICH IS WELL PRESENT AT ALL LEVELS OF THE ATMOSPHERE. IN THE
COURSE OF THE TIMES, THIS RIDGE STRENGTHENS AND MAINTAINS A
WEST-NORTHWEST DIRECTIONAL FLOW ON THE TROPICAL DEPRESSION WHICH WILL
KEEP GLOBALLY THIS TRACK THROUGHOUT ITS LIFE. ALL THE GUIDES ARE IN
GOOD AGREEMENT ON THIS SCENARIO.

AS REGARDS THE FORECAST OF INTENSITY, THE 09 SYSTEM IS AND WILL
REMAIN IN AN ENVIRONMENT UNFAVOURABLE TO INTENSIFICATION: PRESENCE OF
DRY AIR AND STRONG SHEAR AT THE WESTERN EDGE OF THE SYSTEM. DESPITE
THE WEAKENING OF THIS SHEAR OVER THE NEXT 48 HOURS, DRY AIR REMAINS
PRESENT AND TOTALLY LIMITS THE INTENSIFICATION OF THE SYSTEM. THE
MAXIMUM WINDS WILL REMAIN CLOSE TO 30 KNOTS BEFORE WEAKENING
PROGRESSIVELY FROM SUNDAY TO LET THE SYSTEM FILL UP PROGRESSIVELY
DURING ITS TRANSIT NORTH OF THE MASCARENE ISLANDS.

FOR THE MOMENT, THIS LOW INTENSITY SYSTEM DOES NOT PRESENT ANY
PARTICULAR RISK FOR THE INHABITED LANDS.

THE INTENSITY OF THIS SYSTEM DOES NOT REQUIRE THE ISSUANCE OF REGULAR BULLETINS. NEXT BULLETIN TOMORROW AROUND 07UTC.
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