Tropical Cyclone Activity: Indian Ocean (Update 3)

S Indian Ocean: Storm Alert issued at 1 Jan, 2013 18:00 GMT

Tropical Storm DUMILE (07S) currently located near 12.4 S 55.2 E is forecast to strike land to the following likelihood(s) at the given lead time(s):

Yellow Alert Country(s) or Province(s)
    Reunion
        probability for CAT 1 or above is 20% in about 72 hours
        probability for TS is 50% in about 72 hours
Yellow Alert City(s) and Town(s)
    St Pierre (21.3 S, 55.5 E)
        probability for CAT 1 or above is 20% in about 72 hours
        probability for TS is 50% in about 72 hours

Note that
    Yellow Alert (Elevated) is CAT 1 or above to between 10% and 30% probability, or TS to above 50% probability.
    CAT 1 means Tropical Cyclone strength winds of at least 74 mph, 119 km/h or 64 knots 1-min sustained.
    TS means Tropical Storm strength winds of at least 39 mph, 63 km/h or 34 knots 1-min sustained.

012100Z POSITION NEAR 12.8S 55.1E.
TROPICAL CYCLONE (TC) 07S (DUMILE), LOCATED APPROXIMATELY 525 NM 
NORTH OF LA REUNION, HAS TRACKED SOUTHWESTWARD AT 03 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A 
WELL DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) WITH A PRIMARY BAND 
OF DEEP CONVECTION WRAPPING FROM THE SOUTHERN PERIPHERY INTO THE 
NORTHERN HALF OF THE LLCC. THE CONVECTION REMAINS STRONGEST NEAR THE 
CENTER AND IN THE NORTHERN HALF OF THE SYSTEM. THE ORGANIZATION 
REMAINS WELL DEFINED BUT HAS STRUGGLED OVER THE LAST 24 HOURS TO 
INTENSIFY. UPPER LEVEL ANALYSIS INDICATES THE MESOSCALE ANTICYCLONE 
CONTINUES TO PROVIDE GOOD EQUATORWARD OUTFLOW, BUT HAS BEEN WEAK ON 
THE POLEWARD SIDE OF THE SYSTEM. THIS LACK OF STRONG DUAL OUTFLOW 
CHANNELS APPEARS TO BE THE MAIN FACTOR LIMITING STRONGER 
DEVELOPMENT. THE CURRENT INTENSITY OF 45 KNOTS WAS BASED ON DVORAK 
ESTIMATES FROM PGTW AND KNES. ANIMATED WATER VAPOR IMAGERY SHOWS THE 
POLEWARD OUTFLOW CHANNEL HAS STARTED TO IMPROVE IN THE PAST SIX 
HOURS AND SHOULD HELP TO INTENSIFY TC 07S AS IT TRACKS SOUTH-
SOUTHWESTWARD ALONG THE NORTHWESTERN EXTENSION OF A DEEP LAYERED 
SUBTROPICAL RIDGE (STR) LOCATED TO THE SOUTHEAST. A MID-LATITUDE 
TROUGH, TO THE SOUTH OF MADAGASCAR, WILL TRACK EASTWARD WEAKENING 
THE WESTERN EXTENT OF THE STR OVER THE NEXT 24 HOURS. AS THE TROUGH 
TRACKS TO THE SOUTH OF THE STR, THE STR ITSELF WILL SHIFT, BRINGING 
THE TRACK FOR TC 07S MORE SOUTHWARD. IN THE EXTENDED FORECAST, A 
SECOND MID-LATITUDE TROUGH WILL CROSS OVER SOUTHERN AFRICA INTO THE 
INDIAN OCEAN AND AGAIN WEAKEN THE STR, ALLOWING THE TRACK FOR TC 07S 
TO SHIFT TO THE SOUTHEAST. BY TAU 96 THE SYSTEM IS EXPECTED TO BEGIN 
WEAKENING DUE TO INCREASING VERTICAL WIND SHEAR, DECREASING SEA 
SURFACE TEMPERATURES AND INTERACTION WITH THE SECOND MID-LATITUDE 
TROUGH. EXTRA-TROPICAL TRANSITION IS EXPECTED TO BEGIN BY TAU 120. 
MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48 BUT BEGIN TO 
DIFFER IN THE TIMING OF THE RECURVATURE TO THE SOUTHEAST. THIS 
FORECAST REMAINS CONSISTENT WITH THE CONSENSUS OF AVAILABLE MODEL 
GUIDANCE. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 011800Z IS 21 FEET.

- JTWC/TropicalStormRisk.com/Eumetsat