WTIO30 FMEE 080043



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 7/2/20172018

1.A TROPICAL CYCLONE  2  (IRVING)



2.A POSITION 2018/01/08 AT 0000 UTC:

WITHIN 20 NM RADIUS OF POINT 16.8 S / 81.4 E

(SIXTEEN    DECIMAL EIGHT   DEGREES SOUTH AND EIGHTY ONE    DECIMAL

FOUR   DEGREES EAST)

MOVEMENT : SOUTH-WEST 15 KT



3.A DVORAK ANALYSIS: 5.0/5.0/D 1.0/12 H



4.A CENTRAL PRESSURE: 964 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 80 KT

RADIUS OF MAXIMUM WINDS (RMW) :37 KM



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

28 KT NE: 250 SE: 580 SW: 400 NW: 180

34 KT NE: 150 SE: 190 SW: 180 NW: 100

48 KT NE: 110 SE: 130 SW: 120 NW: 80

64 KT NE: 70 SE: 70 SW: 70 NW: 60



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1004 HPA / 1200 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/08 12 UTC: 18.7 S / 78.6 E, MAX WIND=085 KT, TROPICAL

CYCLONE

24H: 2018/01/09 00 UTC: 20.8 S / 75.6 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

36H: 2018/01/09 12 UTC: 23.2 S / 72.8 E, MAX WIND=090 KT, INTENSE

TROPICAL CYCLONE

48H: 2018/01/10 00 UTC: 26.1 S / 70.2 E, MAX WIND=075 KT, TROPICAL

CYCLONE

60H: 2018/01/10 12 UTC: 30.4 S / 68.8 E, MAX WIND=065 KT,

POST-TROPICAL DEPRESSION

72H: 2018/01/11 00 UTC: 36.4 S / 70.7 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :

96H: 2018/01/12 00 UTC: 52.4 S / 78.7 E, MAX WIND=035 KT,

EXTRATROPICAL DEPRESSION





2.C ADDITIONAL INFORMATION:

T=CI=5.0



DURING THE LAST 6 HOURS, THE EYE PATTERN STRENGTHENED ON THE INFRARED

IMAGERY. HOWEVER, AMSR2 1916Z AND 2144Z SSMIS MW IMAGES SHOW A

WEAKNESS IN IRVING'S CORE STRUCTURE, LOCATED IN THE NORTH-EASTERN

SEMI-CIRCLE. THIS COULD BE CAUSED BY A MID-LEVEL SHEAR CONSTRAINT AND

SLOW THE PACE OF INTENSIFICATION OF THE SYSTEM.



STILL NO CHANGE IN TERMS OF 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.



IRVING'S SPEED IS ALLOWING IT TO TOTALLY COMPENSATE THE EFFECTS OF AN

UPPER NORTH-EASTERLY SHEAR CONSTRAINT. THUS, THE SYSTEM IS LIKELY TO

TRACK WITHIN RATHER CONDUCIVE ENVIRONMENTAL CONDITIONS UNTIL TUESDAY

WITH A VERY GOOD UPPER DIVERGENCE, AND POSSIBLY REACH THE INTENSE

TROPICAL CYCLONE STAGE. THEN, AHEAD OF THE UPPER ATMOSPHERIC

DYNAMICS, THE SHEAR SHOULD INCREASE ON WEDNESDAY, THE OCEANIC

POTENTIAL WILL STRONGLY DECREASE SOUTH OF 27S. IRVING SHOULD THEN

BEGIN ITS EXTRATROPICAL TRANSITION BEFORE MERGING WITH A BAROCLINIC

FRONTAL SYSTEM CIRCULATING SOUTH OF 40S.=