WTIO30 FMEE 071836



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 6/2/20172018

1.A TROPICAL CYCLONE  2  (IRVING)



2.A POSITION 2018/01/07 AT 1800 UTC:

WITHIN 15 NM RADIUS OF POINT 15.8 S / 83.0 E

(FIFTEEN    DECIMAL EIGHT   DEGREES SOUTH AND EIGHTY THREE    DECIMAL

ZERO   DEGREES EAST)

MOVEMENT : SOUTH-WEST 18 KT



3.A DVORAK ANALYSIS: 4.5/4.5/D 0.5/6 H



4.A CENTRAL PRESSURE: 979 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 65 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: 90 SE: 100 SW: 100 NW: 70

64 KT NE: 50 SE: 50 SW: 50 NW: 50



7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 800 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/08 06 UTC: 17.4 S / 80.1 E, MAX WIND=075 KT, TROPICAL

CYCLONE

24H: 2018/01/08 18 UTC: 19.7 S / 77.0 E, MAX WIND=080 KT, TROPICAL

CYCLONE

36H: 2018/01/09 06 UTC: 22.3 S / 73.9 E, MAX WIND=085 KT, TROPICAL

CYCLONE

48H: 2018/01/09 18 UTC: 24.9 S / 71.2 E, MAX WIND=085 KT, TROPICAL

CYCLONE

60H: 2018/01/10 06 UTC: 28.3 S / 69.1 E, MAX WIND=070 KT,

POST-TROPICAL DEPRESSION

72H: 2018/01/10 18 UTC: 33.6 S / 69.2 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION



2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=CI=4.5-



DURING THE LAST 6 HOURS, THE EYE PATTERN HAS PROGRESSIVELY

STRENGTHENED. THIS EYE TEMPORARILY EXHIBITED A RAGGED ASPECT BUT THIS

ORGANISATION GAIN JUSTIFIES AN UPGRADE OF IRVING TO THE TROPICAL

CYCLONE STAGE. 1257Z SSMIS IMAGES SHOW A CONSOLIDATING BUT ALREADY

ROBUST CORE. THE UPPER DIVERGENCE STILL LOOKS IMPRESSIVE ON THE SAT

IMAGES WITH CLEAR EVACUATION CHANNELS.



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.



THE SYSTEM IS LIKELY TO KEEP CONDUCIVE ENVIRONMENTAL CONDITIONS UNTIL

TUESDAY WITH A VERY GOOD UPPER DIVERGENCE, ALLOWING IT TO INTENSIFY A

BIT FURTHER. THEN, AHEAD OF THE UPPER ATMOSPHERIC DYNAMICS, THE SHEAR

SHOULD INCREASE AND COULD ADVECT MID-LEVEL DRY AIR NEAR IRVING'S

CORE. THANKS TO ITS SIGNIFICANT SPEED, SHEAR NEGATIVE IMPACTS ARE

LIKELY TO REMAIN LIMITED FOR IRVING AT FIRST. 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.=