WTIO30 FMEE 081856



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 36/1/20172018

1.A MODERATE TROPICAL STORM  1  (AVA)



2.A POSITION 2018/01/08 AT 1800 UTC:

WITHIN 30 NM RADIUS OF POINT 27.1 S / 46.7 E

(TWENTY SEVEN    DECIMAL ONE   DEGREES SOUTH AND FORTY SIX    DECIMAL

SEVEN   DEGREES EAST)

MOVEMENT : WEST 10 KT



3.A DVORAK ANALYSIS: NIL



4.A CENTRAL PRESSURE: 988 HPA

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

RADIUS OF MAXIMUM WINDS (RMW) :NIL



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

28 KT NE: 670 SE: 520 SW: 220 NW: 0

34 KT NE: 300 SE: 330 SW: 0 NW: 0







7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 1100 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : MEDIUM



1.B FORECASTS:

12H: 2018/01/09 06 UTC: 28.8 S / 47.3 E, MAX WIND=035 KT, MODERATE

TROPICAL STORM

24H: 2018/01/09 18 UTC: 31.2 S / 49.7 E, MAX WIND=035 KT,

POST-TROPICAL DEPRESSION

36H: 2018/01/10 06 UTC: 35.3 S / 54.0 E, MAX WIND=040 KT,

EXTRATROPICAL DEPRESSION

48H: 2018/01/10 18 UTC: 41.1 S / 60.8 E, MAX WIND=045 KT,

EXTRATROPICAL DEPRESSION

60H: 2018/01/11 06 UTC: 46.2 S / 67.1 E, MAX WIND=050 KT,

EXTRATROPICAL DEPRESSION

72H: 2018/01/11 18 UTC: 49.2 S / 72.3 E, MAX WIND=055 KT,

EXTRATROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

AVA'S STRUCTURE REMAINS ATYPICAL FOR A TROPICAL STORM WITH A POOR LOW

LEVEL ORGANIZATION SEEN ON LATEST MW IMAGERY ALONG WITH DISPLACED

THUNDERSTORM ACTIVITY FAR AWAY FROM THE CENTER OVER THE EASTERN

SEMI-CIRCLE. ON THE LATEST MSG1 IMAGERY, AN EXPOSED VORTEX IS SEEN

SOUTH OF FORT-DAUPHIN. THE INTENSITY ESTIMATES REMAINS UNCERTAIN BUT

GALES FORCE WINDS ARE STILL ASSUMED OVER THE EASTERN SEMI-CIRCLE.



THE TRACK HAS TURNED WESTWARDS OVER THE LAST 6 HOURS BUT TOMOROW, THE

RIDGE IS FORECASTED TO SHIFT EASTWARD AND AVA SHOULD GRADUALLY CURVE

SOUTHEASTWARD STEERED BY A MID-LATITUDE TROUGH TO ITS SOUTH. MODELS

ARE NOW IN GOOD AGREEMENT IN THIS SCENARIO.



A MODERATE TO STRONG VERTICAL WESTERLY WINDSHEAR SHOULD IS GRADUALLY

AFFECTING THE SYSTEM WHILE OCEAN HEAT CONTENT BECOME INSUFFICIENT.

FROM WEDNESDAY, AVA SHOULD BEGIN TO INTERACT WITH THE SUBTROPICAL

JETSTREAK, AND SHOULD EVOLVE PROGRESSIVELY IN WARM CORE SECLUSION.

AVA EXTRATROPICALISATION PROCESS IS FORECASTED TO BE ACHIEVE FROM

THURSDAY EVACUATING TOWARDS THE MID-LATITUDES.=