WTIO30 FMEE 091217



RSMC / TROPICAL CYCLONE CENTER / LA REUNION

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)



0.A WARNING NUMBER: 13/2/20172018

1.A SEVERE TROPICAL STORM  2  (IRVING)



2.A POSITION 2018/01/09 AT 1200 UTC:

WITHIN 21 NM RADIUS OF POINT 22.3 S / 71.8 E

(TWENTY TWO    DECIMAL THREE   DEGREES SOUTH AND SEVENTY ONE

DECIMAL EIGHT   DEGREES EAST)

MOVEMENT : WEST-SOUTH-WEST 19 KT



3.A DVORAK ANALYSIS: 3.5/4.0/W 1.0/24 H



4.A CENTRAL PRESSURE: 977 HPA

5.A MAX AVERAGE WIND SPEED (10 MN): 55 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 / 600 KM

8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION : DEEP



1.B FORECASTS:

12H: 2018/01/10 00 UTC: 25.4 S / 69.4 E, MAX WIND=055 KT, SEVERE

TROPICAL STORM

24H: 2018/01/10 12 UTC: 29.5 S / 68.4 E, MAX WIND=055 KT,

POST-TROPICAL DEPRESSION

36H: 2018/01/11 00 UTC: 34.7 S / 70.3 E, MAX WIND=050 KT,

POST-TROPICAL DEPRESSION

48H: 2018/01/11 12 UTC: 42.1 S / 77.2 E, MAX WIND=050 KT, DISSIPATING







2.B LONGER-RANGE OUTLOOK :







2.C ADDITIONAL INFORMATION:

T=3.5+ CI=4.0



DURING THE LAST 6 HOURS, THE CONVECTION RELATED TO IRVING IS VERY

FLUCTUATING. THE SSMI PASS AT 1034UTC ALLOWS TO LOCATE THE CENTER

NEAR 21.8S/72.5E. IN THIS SHEAR CONFIGURATION OF IRVING, WE CAN SAY

THAT THE CENTER IS IN THE CONVECTIVE MASS BUT NORTHERN EDGE.



NUMERICAL MODELS REMAIN ENOUGH CONSISTENT OVER THE DIFFERENT ANALYSIS

TIME. RSMC'S TRACK AND INTENSTY FORECAST OF IRVING REMAINS SIMILAR TO

PREVIOUS FORECASTS, 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.=