Cyclone Season 2012: Tropical Storm Irina (Southern Indian Ocean) 3 March 2012 22h00 SAST

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031500Z POSITION NEAR 25.7S 35.0E.
TROPICAL CYCLONE (TC) 14S (IRINA), LOCATED APPROXIMATELY 150 NM EAST OF MAPUTO, MOZAMBIQUE, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS SEEN MARGINAL IMPROVEMENT OVER THE PAST 12 HOURS, WITH THE MAJORITY OF CONVECTION PERSISTING ALONG THE SOUTHWESTERN QUADRANT AND EXTENDING TO THE SOUTHEAST. AN UPPER LEVEL LOW CONTINUES TO CREATE STRONG UPPER LEVEL SUBSIDENCE ALONG THE NORTHERN HALF OF THE LLCC, EVIDENT IN ANIMATED WATER VAPOR IMAGERY. THE CURRENT INTENSITY IS BASED ON A 030716Z ASCAT PASS SHOWING 35 TO 40 KNOT WINDS ALONG THE SOUTHERN PERIPHERY. TC 14S IS TRACKING ALONG THE NORTHERN PERIPHERY OF A TRANSITORY LOW- TO MID-LEVEL ANTICYCLONE. THE CURRENT FORECAST INDICATES THE ANTICYCLONE WILL WEAKEN ALONG THE WESTERN HALF AS A DEVELOPING MID-LATITUDE TROUGH OVER SOUTHERN AFRICA TRACKS EASTWARD BRINGING THE TRACK SOUTHWARD. BY TAU 72 THE TROUGH WILL HAVE MOVED FURTHER TO THE EAST ALLOWING A NEW ANTICYCLONE TO BUILD TO THE SOUTH OF TC 14S. THIS WILL CAUSE TC 14S TO TRACK INTO SOUTHERN MOZAMBIQUE BETWEEN TAU 96 AND 120. INTENSITY IS EXPECTED TO INCREASE SLIGHTLY OVER THE NEXT 12 TO 24 HOURS MAINTAINING WEAK TROPICAL CYCLONE STRENGTH AS THE SUBSIDENCE ALONG THE NORTHERN HALF OF THE SYSTEM HINDERS MORE
SIGNIFICANT DEVELOPMENT. SEA SURFACE TEMPERATURES (SSTS) WILL REMAIN BETWEEN 27 TO 28 DEGREES CELSIUS ALONG THE FORECAST TRACK, ONLY MARGINALLY FAVORABLE FOR SUSTAINING THE INTENSITY. IN LATER TAUS THE LOW LEVEL STRUCTURE WILL WEAKEN DUE TO POOR SSTS SOUTH OF 26 DEGREES SOUTH AND DIMINISHING UPPER LEVEL SUPPORT. BY TAU 96, TC 14S WILL MAKE LANDFALL LEADING TO THE LLCC DISSIPATING OVER LAND BY TAU 120. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 031200Z IS 12 FEET.

- JTWC