WTIO30 FMEE 201844
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 19/11/20202021
1.A SEVERE TROPICAL STORM 11 (GUAMBE)

2.A POSITION 2021/02/20 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 27.2 S / 36.6 E
(TWENTY SEVEN DECIMAL TWO DEGREES SOUTH AND
THIRTY SIX DECIMAL SIX DEGREES EAST)
MOVEMENT: SOUTH-SOUTH-EAST 6 KT

3.A DVORAK ANALYSIS: 3.5/3.5/S 0.0/6 H

4.A CENTRAL PRESSURE: 983 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 50 KT
RADIUS OF MAXIMUM WINDS (RMW): 46 KM

6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 360 SE: 370 SW: 295 NW: 130
34 KT NE: 120 SE: 120 SW: 100 NW: 75
48 KT NE: 65 SE: 85 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1003 HPA / 600 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/02/21 06 UTC: 28.7 S / 37.6 E, VENT MAX= 055 KT, SEVERE
TROPICAL STORM
28 KT NE: 380 SE: 345 SW: 280 NW: 260
34 KT NE: 195 SE: 230 SW: 195 NW: 195
48 KT NE: 100 SE: 95 SW: 95 NW: 95

24H: 2021/02/21 18 UTC: 31.0 S / 40.2 E, VENT MAX= 070 KT, TROPICAL
CYCLONE
28 KT NE: 400 SE: 315 SW: 380 NW: 315
34 KT NE: 195 SE: 220 SW: 260 NW: 220
48 KT NE: 100 SE: 110 SW: 120 NW: 100
64 KT NE: 55 SE: 55 SW: 65 NW: 65

36H: 2021/02/22 06 UTC: 33.9 S / 45.7 E, VENT MAX= 075 KT, TROPICAL
CYCLONE
28 KT NE: 470 SE: 425 SW: 785 NW: 425
34 KT NE: 230 SE: 305 SW: 470 NW: 325
48 KT NE: 110 SE: 130 SW: 165 NW: 110
64 KT NE: 65 SE: 75 SW: 65 NW: 75

48H: 2021/02/22 18 UTC: 36.7 S / 54.0 E, VENT MAX= 060 KT, SEVERE
TROPICAL STORM
28 KT NE: 425 SE: 350 SW: 760 NW: 325
34 KT NE: 205 SE: 270 SW: 445 NW: 250
48 KT NE: 120 SE: 110 SW: 150 NW: 130

60H: 2021/02/23 06 UTC: 38.2 S / 61.7 E, VENT MAX= 040 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 380 SE: 280 SW: 345 NW: 220
34 KT NE: 175 SE: 220 SW: 230 NW: 185

72H: 2021/02/23 18 UTC: 39.6 S / 68.4 E, VENT MAX= 030 KT,
POST-TROPICAL DEPRESSION
28 KT NE: 345 SE: 120 SW: 195 NW: 65

2.B LONGER-RANGE OUTLOOK:
NIL


2.C ADDITIONAL INFORMATION:
T=CI=3.5

STILL NO MICROWAVE DATA FOR THE LAST 6 HOURS AND THE LAST PARTIAL
ASCAT SWATH PROVIDES LITTLE INFORMATION. USING INFRARED SATELLITE
DATA, IT CAN BE SEEN THAT THE CURVED BAND CONFIGURATION IS STILL
VALID WITH TOPS COOLING DOWN IN THE LAST FEW MOMENTS. THE SUSPICION
OF A EYEWALL REPLACEMENT CYCLE COMBINED WITH AN OCEANIC POTENTIAL
THAT WAS BEGINNING TO BE LIMITING COULD EXPLAIN THE OBSERVED
WEAKENING OF GUAMBE DURING THE LAST 12-18 HOURS. THIS WEAKENING SEEMS
TO BE OVER WITH THE MAINTAINING OF A DVORAK ANALYSIS AT 3.5 LEAVING
GUAMBE STILL IN THE SEVERE TROPICAL STORM STAGE.

GUAMBE RETAINS A GENERAL SOUTH-SOUTHEASTWARD MOVEMENT UNDER THE
INFLUENCE OF THE SUBTROPICAL RIDGE TO THE EAST OF THE SYSTEM. WITH
THE APPROACH OF A MID-LATITUDE TROUGH FROM THE SOUTH, GUAMBE IS
PLACED ON A DEFINITE SOUTH-EAST TRACK AND WILL SHOW A MARKED
ACCELERATION DURING THE DAY ON SUNDAY. THIS WILL SIGNAL ITS
EVACUATION TOWARDS THE MIDDLE LATITUDES, TAKEN IN THE FOLLOW OF THE
TROUGH WHICH CIRCULATES MORE IN THE SOUTH. THE AVAILABLE MODELS ARE
RELATIVELY LITTLE DISPERSED AROUND THIS SCENARIO IN TERMS OF
DIRECTION BUT STILL PRESENT IMPORTANT DIFFERENCES IN TERMS OF
EVACUATION SPEED.

NO CHANGE IN TERMS OF INTENSITY FORECAST: GUAMBE SHOULD RESUME AN INTENSIFICATION IN THE SHORT TERM IN AN ENVIRONMENT THAT REMAINS
FAVORABLE WITH A STRONG DIVERGENCE OF ALTITUDE, ESPECIALLY ON THE
SOUTH SIDE, AND A SHEAR REMAINING IN REASONABLE PROPORTIONS. THANKS
TO A RESUMPTION OF ITS DISPLACEMENT, GUAMBE FINDS ITSELF AGAIN WITH A SUFFICIENT OCEANIC POTENTIAL AND THIS UNTIL AROUND 30. FROM SUNDAY
EVENING, THE NORTHWESTERN SHEAR SHOULD GRADUALLY STRENGTHEN IN FRONT
OF THE MID-LATITUDE TROUGH AND LEAD TO THE WEAKENING OF THE SYSTEM.
THE ACCELERATION OF GUAMBE IN THE DIRECTION OF THE SHEAR SHOULD MAKE
IT RESIST AND IT WILL THEN START TO LOSE ITS PURELY TROPICAL
CHARACTERISTICS AT QUITE SOUTHERN LATITUDES, ON MONDAY LATE IN THE
DAY OR THE FOLLOWING NIGHT.

AS GUAMBE CONTINUES TO MOVE AWAY FROM THE MOZAMBICAN COAST, WEATHER
CONDITIONS IN SOUTHERN MOZAMBIQUE ARE IMPROVING.
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