WTIO30 FMEE 081915



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 10/2/20172018

1.A TROPICAL CYCLONE  2  (IRVING)



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

WITHIN 30 NM RADIUS OF POINT 19.2 S / 76.8 E

(NINETEEN    DECIMAL TWO   DEGREES SOUTH AND SEVENTY SIX    DECIMAL

EIGHT   DEGREES EAST)

MOVEMENT : WEST-SOUTH-WEST 18 KT



3.A DVORAK ANALYSIS: 4.0/4.5/W 0.5/24 H



4.A CENTRAL PRESSURE: 970 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 70 KT

RADIUS OF MAXIMUM WINDS (RMW) :65 KM



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

28 KT NE: 210 SE: 570 SW: 500 NW: 150

34 KT NE: 160 SE: 390 SW: 360 NW: 120

48 KT NE: 90 SE: 140 SW: 130 NW: 70

64 KT NE: 60 SE: 90 SW: 90 NW: 0



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 700 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/09 06 UTC: 21.0 S / 73.9 E, MAX WIND=065 KT, TROPICAL

CYCLONE

24H: 2018/01/09 18 UTC: 23.6 S / 70.5 E, MAX WIND=060 KT, SEVERE

TROPICAL STORM

36H: 2018/01/10 06 UTC: 26.8 S / 68.2 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

48H: 2018/01/10 18 UTC: 31.5 S / 68.1 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION

60H: 2018/01/11 06 UTC: 37.4 S / 73.1 E, MAX WIND=040 KT,

POST-TROPICAL DEPRESSION





2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=4.0+ CI=4.5+



THE EFFECTS OF THE NORTHEASTERN CONSTRAINT ARE MORE AND MORE VISIBLE

ON THE DEEP CONVECTION. THE CLOUD PATTERN HAS DETRIORATED

SIGNIFICANTLY AND SHIFT FROM AN EYE PATTERN TO EMBEDDED CENTER.

ASCAT-A PASS OF 1602Z WAS USEFUL FOR POSITIONING THE CENTER AND

ASSESS THE WIND STRUCTURE.



STILL NO CHANGE IN TERMS OF TRACK FORECAST FOR IRVING, ALL NUMERICAL

MODELS ARE IN EXCELLENT AGREEMENT ON ITS EVOLUTION, DEFINING THEN A

GOOD CONFIDENCE IN THIS FORECAST. IRVING'S TRACK IS STEERED BY A

STRONG RIDGE IN THE SOUTH-EAST. FROM WEDNESDAY, IRVING SHOULD BE

ATTRACTED SOUTH-EASTWARDS TOWARD THE MID-LATITUDES BY A TROUGH

ARRIVING FROM THE SOUTH-WEST.



ON WEDNESDAY, THE OCEANIC POTENTIAL WILL STRONGLY DECREASE SOUTH OF

27S. IRVING SHOULD THEN BEGIN ITS EXTRATROPICAL TRANSITION BEFORE

MERGING WITH THE SYSTEM EX-AVA, THEN WITH A BAROCLINIC FRONTAL SYSTEM

CIRCULATING SOUTH OF 40S.=