WTIO30 FMEE 090612



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 12/2/20172018

1.A SEVERE TROPICAL STORM  2  (IRVING)



2.A POSITION 2018/01/09 AT 0600 UTC:

WITHIN 21 NM RADIUS OF POINT 21.6 S / 73.9 E

(TWENTY ONE    DECIMAL SIX   DEGREES SOUTH AND SEVENTY THREE

DECIMAL NINE   DEGREES EAST)

MOVEMENT : SOUTH-WEST 18 KT



3.A DVORAK ANALYSIS: 4.0/4.5/W 1.0/24 H



4.A CENTRAL PRESSURE: 975 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 60 KT

RADIUS OF MAXIMUM WINDS (RMW) :56 KM



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

28 KT NE: 310 SE: 570 SW: 370 NW: 190

34 KT NE: 190 SE: 410 SW: 260 NW: 150

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





7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1006 HPA / 500 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/09 18 UTC: 24.2 S / 70.9 E, MAX WIND=055 KT, SEVERE

TROPICAL STORM

24H: 2018/01/10 06 UTC: 27.1 S / 69.5 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

36H: 2018/01/10 18 UTC: 31.7 S / 69.1 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION

48H: 2018/01/11 06 UTC: 39.1 S / 73.7 E, MAX WIND=050 KT, DISSIPATING







2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=4.0- CI=4.5-



DURING THE LAST 6 HOURS, THE NORTH-NORTH-EASTERLY CONSTRAINT WAS WELL

ATTENUATED THE DEEP CONVECTION ASSOCIATED TO IRVING. THE LAST IR DATA

ALLOW TO LOCATE THE CENTER NEAR THE EASTERN EDGE OF THE CONVECTION,

WHICH CONFIRMS THE SSMI PASS AT 0138UTC AND AMSU-B AT 0231UTC. THE

LOCATION OF THE CENTER SHOWS A SLIGHT INFLECTION IN THE TRACK.



TRACK AND INTENSTY FORECAST OF IRVING REMAIN ROBUST DURING NUMERICAL

MODELS RUNS, EVEN IF THE CHRONOLOGY OF THE RECURVATURE BEGINS A

LITTLE BEFORE. IRVING'S TRACK IS STEERED BY A STRONG RIDGE IN THE

SOUTH-EAST, BEFORE BEING CATCHED DURING WEDNESDAY BY A BROAD

BAROCLINIC LOW PRESSURE SYSTEM  THAT WILL PREVIOUSLY ABSORB AVA. IN

THIS CONTEXT, IRVING WILL SWITCH IN A CLASSIFICATION OF A

POST-TROPICAL DEPRESSION AND RECURVATURE TOWARDS THE SOUTH-EAST AT A

STILL FAST MOTION IS EXPECTED BY THAT TIME. AT THE END OF THE

FORECAST RANGE, THE SYSTEM IS EXPECTED TO MERGE WITH A COLD FRONT.=