WTIO30 FMEE 310103
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 5/1/20232024
1.A TROPICAL DISTURBANCE 1
2.A POSITION 2023/12/31 AT 0000 UTC:
WITHIN 30 NM RADIUS OF POINT 20.0 S / 38.1 E
(TWENTY DECIMAL ZERO DEGREES SOUTH AND
THIRTY EIGHT DECIMAL ONE DEGREES EAST)
MOVEMENT: EAST-SOUTH-EAST 7 KT
3.A DVORAK ANALYSIS: 1.5/1.5/D 0.5/6 H
4.A CENTRAL PRESSURE: 1003 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 25 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
NIL
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2023/12/31 12 UTC: 20.9 S / 39.3 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 155 SE: 230 SW: 240 NW: 120
24H: 2024/01/01 00 UTC: 21.6 S / 41.1 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 175 SE: 250 SW: 240 NW: 130
34 KT NE: 110 SE: 140 SW: 140 NW: 85
36H: 2024/01/01 12 UTC: 21.8 S / 42.6 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 195 SE: 270 SW: 240 NW: 150
34 KT NE: 130 SE: 150 SW: 140 NW: 85
48H: 2024/01/02 00 UTC: 21.7 S / 44.1 E, VENT MAX= 030 KT, OVERLAND
DEPRESSION
28 KT NE: 220 SE: 285 SW: 240 NW: 155
60H: 2024/01/02 12 UTC: 21.4 S / 45.4 E, VENT MAX= 020 KT, OVERLAND
DEPRESSION
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
OVER THE PAST 6 HOURS, CONVECTION IN THE WESTERN QUADRANT HAS
CONTINUED TO INTENSIFY, WITH A BURST OF DEEP CONVECTION OVERNIGHT. IN
ADDITION, ASCAT PASSES B AND C FROM 1853Z AND 1945Z SHOW A CLOSED
CIRCULATION AROUND THE CENTER, BUT STILL ELONGATED, AND AN
ASYMMETRICAL DISTRIBUTION OF WINDS. IN FACT, THE STRONGEST WINDS ARE
EXCLUSIVELY IN THE WESTERN QUADRANT, WITH 25KT AND HIGHER
ACCELERATIONS UNDER THE CONVECTION. TAKING INTO ACCOUNT THESE DATA
AND THE CURRENT LACK OF ORGANIZATION, MAXIMUM WINDS ARE MAINTAINED AT
25KT.
THE SYSTEM CONTINUES TO CROSS THE MOZAMBIQUE CHANNEL, UNDER THE
INFLUENCE OF A WEST-NORTH-WEST DIRECTIONAL FLOW BETWEEN A
NEAR-EQUATORIAL RIDGE TO THE NORTH AND A WEAK SUBTROPICAL RIDGE
ATTENUATED BY A TROUGH TO THE SOUTH. ITS TRACK WILL TAKE IT TO THE
WEST COAST OF MADAGASCAR, WHICH IT MAY REACH LATER ON MONDAY OR
DURING THE NIGHT OF MONDAY TO TUESDAY. THE DISPERSION OF NUMERICAL
FORECASTS IS QUITE SIGNIFICANT FOR ITS SPEED OF MOVEMENT, WITH A BIG
DIFFERENCE BETWEEN GFS AND THE OTHER MODELS. THE TRACK FORECASTED BY
RSMC IS CLOSE TO THE LATEST RUNS BY IFS AND AROME IN TERMS OF TIMING.
ON THE OTHER HAND, UNTIL NOW, THE GFS SCENARIO, WHICH PROPOSED AN
EMERGENCE OF THE SYSTEM TO THE EAST OF MADAGASCAR, WAS RELATIVELY
ISOLATED (THE OTHERS SUGGESTED THE FORMATION OF A SECOND DISTINCT
MINIMUM TO THE EAST OF MADAGASCAR). THE LATEST RUNS OF THE IFS AND
AROME DETERMINIST MODELS, AS WELL AS EUROPEAN PROBABILISTS, ARE ALSO
BEGINNING TO SUGGEST THIS OPTION. THIS IS NOT CURRENTLY THE SCENARIO
FOLLOWED BY RSMC, BUT IT IS NOT COMPLETELY EXCLUDED.
IN TERMS OF INTENSITY, ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR THE
DEVELOPMENT IN THE SHORT TERM, WITH FAIRLY GOOD POLAR LOW-LEVEL
CONVERGENCE, STRONG OCEANIC POTENTIAL AND RELATIVELY LOW VERTICAL
WIND SHEAR. FROM SUNDAY EVENING OR MONDAY, THE MID-LEVEL WESTERLY TO
SOUTH-WESTERLY SHEAR IS SET TO STRENGTHEN, BRINGING STRENGTHEN,
BRINGING DRY AIR TO THE MID-TROPOSPHERE. THIS CONTRIBUTION OF DRY AIR
COULD SLOW THE DEVELOPMENT OF THE SYSTEM, DESPITE AN IMPROVEMENT IN
LOW-LEVEL CONVERGENCE ON THE EQUATORIAL COAST (BETTER WARM AND HUMID
SUPPLY FROM THE MONSOON FLOW). THE CURRENT FORECAST THEREFORE
SUGGESTS AN INTENSIFICATION UNTIL SUNDAY NIGHT INTO MONDAY, FOLLOWED
BY A LEVELLING OFF IN INTENSITY DUE TO THE EFFECTS OF SHEAR. THE
SYSTEM COULD THEN REACH THE MODERATE TROPICAL STORM STAGE BEFORE
APPROACHING MADAGASCAR ON MONDAY.
IMPACTS ON INHABITED LAND :
MOZAMBIQUE: GRADUAL EASING OF RAINFALL ON SUNDAY.
MADAGASCAR (SOUTHERN MORONDAVA PROVINCE, NORTHERN TOLIARA PROVINCE,
FIANARANTSOA PROVINCE):
- GALE-FORCE WINDS LIKELY TO ARRIVE FROM MIDDAY ON MONDAY UNTIL
MONDAY NIGHT.
- HEAVY RAIN FROM MONDAY ON THE WEST COAST, EXTENDING TO THE EAST
COAST ON TUESDAY. ACCUMULATIONS OF 100-200MM, LOCALLY 300M.
- WAVES CLOSE TO 4M NEAR THE IMPACT ZONE AROUND MONDAY EVENING.=
