WTIO30 FMEE 311827
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER: 3/6/20202021
1.A TROPICAL DISTURBANCE 6

2.A POSITION 2020/12/31 AT 1800 UTC:
WITHIN 25 NM RADIUS OF POINT 12.1 S / 72.9 E
(TWELVE DECIMAL ONE DEGREES SOUTH AND
SEVENTY TWO DECIMAL NINE DEGREES EAST)
MOVEMENT: NORTH-NORTH-EAST 2 KT

3.A DVORAK ANALYSIS: 1.5/1.5/S 0.0/18 H

4.A CENTRAL PRESSURE: 1001 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):
28 KT NE: 0 SE: 0 SW: 0 NW: 0

7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 600 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/01/01 06 UTC: 11.8 S / 73.2 E, VENT MAX= 025 KT, TROPICAL
DISTURBANCE

24H: 2021/01/01 18 UTC: 11.7 S / 73.5 E, VENT MAX= 025 KT, TROPICAL
DISTURBANCE

36H: 2021/01/02 06 UTC: 11.7 S / 73.7 E, VENT MAX= 030 KT, TROPICAL
DEPRESSION
28 KT NE: 65 SE: 140 SW: 165 NW: 35

48H: 2021/01/02 18 UTC: 11.9 S / 74.2 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 95 SE: 140 SW: 165 NW: 85
34 KT NE: 85 SE: 100 SW: 75 NW: 75

60H: 2021/01/03 06 UTC: 13.2 S / 75.2 E, VENT MAX= 035 KT, MODERATE
TROPICAL STORM
28 KT NE: 100 SE: 140 SW: 165 NW: 85
34 KT NE: 95 SE: 110 SW: 75 NW: 75

72H: 2021/01/03 18 UTC: 14.8 S / 75.3 E, VENT MAX= 040 KT, MODERATE
TROPICAL STORM
28 KT NE: 110 SE: 140 SW: 165 NW: 85
34 KT NE: 100 SE: 110 SW: 75 NW: 75

2.B LONGER-RANGE OUTLOOK:
96H: 2021/01/04 18 UTC: 16.1 S / 74.8 E, VENT MAX= 055 KT, SEVERE
TROPICAL STORM
28 KT NE: 130 SE: 140 SW: 165 NW: 95
34 KT NE: 120 SE: 130 SW: 85 NW: 85
48 KT NE: 85 SE: 75 SW: 75 NW: 75

120H: 2021/01/05 18 UTC: 16.8 S / 72.9 E, VENT MAX= 075 KT, TROPICAL
CYCLONE
28 KT NE: 155 SE: 150 SW: 165 NW: 100
34 KT NE: 150 SE: 140 SW: 85 NW: 95
48 KT NE: 90 SE: 80 SW: 70 NW: 80
64 KT NE: 60 SE: 50 SW: 60 NW: 60

2.C ADDITIONAL INFORMATION:

OVER THE LAST 6 HRS, CONVECTION INTENSIFIED CLOSER TO THE CENTER
PROBABLY THANKS TO THE EFFECTS OF THE DIURNAL CYCLE. THE CLOUD
PATTERN REMAINS GLOBALLY WEAK BECAUSE OF A STRONG SHEAR CONSTRAINT
THAT REJECTS CONVECTION IN THE SOUTHWESTERN SEMI-CIRCLE. SOME
MID-LEVEL DRY AIR ALSO OCCUPY THE NORTHERN SEMI-CIRCLE.

TROPICAL DISTURBANCE 6 REMAINS QUASI-STATIONARY FOR NOW, NESTED
WITHIN THE MONSOON TROUGH. THIS WEEK-END, IT IS EXPECTED TO BEGIN TO
MOVE SOUTH-EASTWARDS AS IT INTERACTS WITH THE SYSTEM 5 (FUJIWHARA
EFFECT) AND UNDER THE INFLUENCE OF THE MONSOON FLOW. FROM SUNDAY, THE CIRCULATION SHOULD MERGE WITH SYSTEM 5. THEN, THE AVAILABLE GUIDANCE
SUGGEST A GLOBALLY WESTWARD TRACK ON THE NORTHERN SIDE OF A WIDE
SUBTROPICAL RIDGE.

THE SYSTEM REMAINS UNDERMINED BY A STRONG EASTERLY SHEAR UNTIL
TOMORROW NIGHT. FROM SATURDAY, THE UPPER CONDITIONS BECOME MORE
FAVORABLE TO THE DEVELOPMENT OF THE SYSTEM WITH EVEN AN INCREASING
UPPER DIVERGENCE. HOWEVER, THE INTERACTION WITH SYSTEM 5 ARRIVING
FROM THE EAST SHOULD SIGNIFICANTLY AFFECT THE LOW-LEVEL CONDITIONS.
THE AVAILABLE GUIDANCE IS CURRENTLY STRUGGLING TO CHOOSE WHICH
CIRCULATION WILL ABSORB THE OTHER. THE AVAILABLE MODELS HAVE CHANGED
THEIR SCENARIO ON THE LAST TWO RUNS AND ARE NOW SUGGESTING THE
PREVALENCE OF SYSTEM 6 OVER SYSTEM 5, AS THE LATTER UNDERCUTS THE
EQUATORIAL LOW-LEVEL CONVERGENCE OF ITS RIVAL. FROM THE BEGINNING OF
NEXT WEEK, THE REMAINING SYSTEM SHOULD BENEFIT FROM RATHER CONDUCIVE
CONDITIONS FOR ITS DEVELOPMENT EVEN IF SOME MID-LEVEL DRY AIR IN THE
SOUTH COULD LIMIT THE PACE OF INTENSIFICATION.

SIMILAR TO THE FORECAST OF SYSTEM 05, THE CONFIDENCE IN TRACK AND
INTENSITY REMAINS LOW, AS THE TWO SYSTEMS ARE EXPECTED TO INTERACT
WITH EACH OTHER. ONE OF THE TWO SHOULD EVENTUALLY DOMINATE THE OTHER
BUT IS IS NOT IMPOSSIBLE THAT BOTH SYSTEM INCAPACITATE EACH OTHER.

THE CURRENT INTENSITY DOES NOT REQUIRE THE ISSUANCE OF REGULAR
ADVISORIES.
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