WTIO30 FMEE 080639



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 34/1/20172018

1.A MODERATE TROPICAL STORM  1  (AVA)



2.A POSITION 2018/01/08 AT 0600 UTC:

WITHIN 20 NM RADIUS OF POINT 25.3 S / 48.8 E

(TWENTY FIVE    DECIMAL THREE   DEGREES SOUTH AND FORTY EIGHT

DECIMAL EIGHT   DEGREES EAST)

MOVEMENT : SOUTH 8 KT



3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/6 H



4.A CENTRAL PRESSURE: 988 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 35 KT

RADIUS OF MAXIMUM WINDS (RMW) :37 KM



6.A EXTENSION OF WIND BY QUADRANTS (KM):

28 KT NE: 200 SE: 170 SW:  NW:

34 KT NE: 90 SE: 70 SW:  NW:







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1005 HPA / 1500 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/08 18 UTC: 27.3 S / 47.7 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

24H: 2018/01/09 06 UTC: 29.5 S / 48.0 E, MAX WIND=045 KT, MODERATE

TROPICAL STORM

36H: 2018/01/09 18 UTC: 31.5 S / 49.3 E, MAX WIND=040 KT, MODERATE

TROPICAL STORM

48H: 2018/01/10 06 UTC: 33.9 S / 51.7 E, MAX WIND=030 KT,

POST-TROPICAL DEPRESSION

60H: 2018/01/10 18 UTC: 36.0 S / 55.8 E, MAX WIND=030 KT,

POST-TROPICAL DEPRESSION

72H: 2018/01/11 06 UTC: 37.4 S / 61.8 E, MAX WIND=030 KT,

EXTRATROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

SINCE THIS NIGHT, DEEP CONVECTION HAS RE-BUILT AND HAS MAINTAINED

NEAR THE CENTER, LOCATED ESSENTIALLY WITHIN THE EASTERN SEMI-CIRCLE.

0515Z PARTIAL ASCAT SHOWS AGAIN GALE WINDS OVER THE EASTERN

SEMI-CIRCLE.



STEERED BY A MID-LATITUDE TROUGH TO ITS SOUTH, EX-AVA MOVES

SOUTHWARD. THE SYSTEM IS FORECASTED TO SLOW DOWN TODAY BEFORE

RE-ACCELERATE PROGRESSIVELY SOUTHEASTWARD FROM TOMOROW. MODELS ARE

NOW IN GOOD AGREEMENT IN THIS TRACK.



AVA SEEMS START A NEW CYCLE OF INTENSIFICATION. ENVIRONNEMENTAL

CONDITIONS ARE EXPECTED TO REMAIN CONDUCIVE DURING THE NEXT 24 HOURS

WITH A GOOD LEVEL UPPER DIVERGENCE, A WEAK VERTICAL WINDSHEAR BUT

WITH AN OCEANIC HEAT CONTENT (OHC)THAT STARTS TO BECOME WEAK.

FROM THURSDAY, A MODERATE TO STRONG VERTICAL WESTERN WINDSHEAR SHOULD

AFFECT THE SYSTEM WHILE OHC WILL BECOME TOO INSUFFICIENT. AVA SHOULD

BEGIN TO INTERACT WITH THE SUBTROPICAL JETSTREAK, EVOLVE

PROGRESSIVELY IN WARM SECLUSION AND CONCLUDE ITS EXTRATROPICALISATION

PROCESS FROM THURSDAY EVACUATING TOWARDS THE MID-LATITUDES.=