WTIO30 FMEE 061833
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 3/3/20202021
1.A TROPICAL DEPRESSION 3
2.A POSITION 2020/12/06 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 13.4 S / 83.8 E
(THIRTEEN DECIMAL FOUR DEGREES SOUTH AND
EIGHTY THREE DECIMAL EIGHT DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 13 KT
3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/24 H
4.A CENTRAL PRESSURE: 998 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: 260 SW: 260 NW: 0
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1008 HPA / 700 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2020/12/07 06 UTC: 14.6 S / 81.8 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 55 SE: 280 SW: 250 NW: 75
34 KT NE: 45 SE: 75 SW: 110 NW: 65
24H: 2020/12/07 18 UTC: 15.1 S / 79.8 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 45 SE: 260 SW: 220 NW: 75
34 KT NE: 35 SE: 65 SW: 95 NW: 65
36H: 2020/12/08 06 UTC: 16.2 S / 77.8 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 45 SE: 260 SW: 205 NW: 75
34 KT NE: 35 SE: 65 SW: 75 NW: 65
48H: 2020/12/08 18 UTC: 17.6 S / 76.3 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 45 SE: 75 SW: 120 NW: 75
34 KT NE: 35 SE: 65 SW: 30 NW: 65
60H: 2020/12/09 06 UTC: 18.5 S / 75.5 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 20 SE: 75 SW: 205 NW: 85
72H: 2020/12/09 18 UTC: 18.6 S / 74.5 E, VENT MAX= 025 KT, REMNANT
LOW
2.B LONGER-RANGE OUTLOOK:
96H: 2020/12/10 18 UTC: 18.0 S / 70.5 E, VENT MAX= 025 KT, REMNANT
LOW
2.C ADDITIONAL INFORMATION:
T=CI=2.5
THE CLOUD PATTERN HAS IMPROVED OVERALL OVER THE LAST 6 HOURS WITH A
CURVED BAND STEADY WRAPPING A HALF TURN AROUND A LOG10 SPIRAL. THE
LATEST SUBJECTIVE DVORAK ESTIMATES ARE BETWEEN 2.0 AND 2.5. SINCE
1630Z, CONVECTIVE ACTIVITY HAS BEEN INCREASING NEAR THE CENTER IN THE
SOUTHWESTERN QUADRANT. A SCATSAT PASS OF 1330Z SUGGESTS THAT NEAR
GALE FORCE WINDS, WITH LOCALLY GALE FORCE WINDS, ARE PRESENT IN THE
SOUTHERN SEMICIRCLE BUT THAT WINDS REMAIN WEAK AT 10-15 KT IN THE
NORTHERN SEMICIRCLE. BASED ON THESE ELEMENTS, THE FINAL INTENSITY IS
SET AT 30 KT.
LITTLE CHANGE IN THE PHILOSOPHY OF TRAJECTORY PREDICTION: IT KEEPS A
WEST-SOUTHWEST OR SOUTHWEST ORIENTATION DUE TO THE INFLUENCE OF THE
SUBTROPICAL RIDGE FURTHER SOUTH, UNTIL THE NIGHT OF MONDAY TO
TUESDAY. AS A DEEP LAYERS TROUGH PASS FURTHER SOUTH, THE TRACK TAKES
A TEMPORARY SOUTH-SOUTHWEST COMPONENT BEFORE THE SUBTROPICAL RIDGE
IMPOSES AGAIN A WESTERLY TRAJECTORY.
ALONG THIS TRACK, THE SYSTEM NR 03 CONTINUES TO BENEFIT FROM A RATHER
FAVOURABLE WINDOW DURING THE NEXT 24/30H: IF THE DEEP WIND SHEAR IS
LOW, THE UPPER LEVELS DIVERGENCE IS SUFFICIENT AND THE OCEANIC
POTENTIAL IS WELL AVAILABLE, THE SYSTEM COULD STILL BE SUBJECTED
TOMORROW TO A NORTH-WESTERLY MID-LEVELS SHEAR WHICH WILL TEND TO
INCREASE AFTER 24/30H. UNDER THESE CONDITIONS, THE SYSTEM NR 03
SHOULD BE ABLE TO REACH THE THRESHOLD OF MODERATE TROPICAL STORM ON
MONDAY AND MORE OR LESS REMAIN THERE ON TUESDAY WITH A LESS
FAVOURABLE ENVIRONMENT. THEREAFTER, VERTICAL WIND SHEAR INCREASES AND
IS ASSOCIATED WITH MARKED MID-LEVELS DRY INTRUSIONS. THE SYSTEM
SHOULD THEN RAPIDLY EVOLVE INTO A REMNANT LOW.
THIS SYSTEM POSE NO THREAT TO INHABITED AREAS.=
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