Update: Cyclone Season 2012: Tropical Cyclone Giovanna (Southern Indian Ocean) 19 February 2012 09h00 SAST

190300Z POSITION NEAR 25.9S 47.7E.
TROPICAL CYCLONE 12S (GIOVANNA), LOCATED APPROXIMATELY 430 NM SOUTH OF ANTANANARIVO, MADAGASCAR, HAS TRACKED EAST-NORTHEASTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS DEEP CONVECTION HAS PERSISTED WITH THE SUPPORT OF A STRONG POLEWARD OUTFLOW CHANNEL. THE EYE FEATURE HAS BROKEN DOWN OVER THE PAST 12 HOURS, HOWEVER DVORAK ESTIMATES FROM PGTW AND KNES CONTINUE TO SHOW AN INTENSE SYSTEM. TC 12S HAS SPED UP OVER THE PAST 12 HOURS AND IS BEGINNING TO TURN SLIGHTLY NORTHWARD IN THAT LAST SIX HOURS. UPPER LEVEL ANALYSIS INDICATES TC 12S REMAINS IN LOW TO MODERATE VERTICAL WIND SHEAR (VWS) (10-15 KNOTS). THE MAIN IMPEDIMENT TO DEVELOPMENT IN THE SHORT TERM IS CONTINUED INTERACTION WITH THE ISLAND OF MADAGASCAR TO THE NORTH. IN THE LONG TERM, THE VWS WILL INCREASE AS TC 13S APPROACHES FROM THE NORTHEAST. TC 12S IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED OVER SOUTH AFRICA. THE SYSTEM IS FORECAST TO WEAKEN GRADUALLY, AND SHOULD MAKE A CURVE TO THE NORTH AFTER TAU 36. NUMERICAL GUIDANCE HAS SPLIT RECENTLY WITH NGPS, GFS, WBAR, AND GFDN SHOWING A TURN TO THE SOUTHEAST. ECMF AND EGRR REMAIN WITH A TURN NORTHWARD. THIS FORECAST PREFERS THE ECMF SOLUTION, HOWEVER THERE IS SOME CONCERN REGARDING THIS FORECAST AS TC 13S HAS NOT DEVELOPED AS STRONGLY AS MODEL GUIDANCE SUGGESTS. THIS COULD PROVIDE AN ALTERNATE SCENARIO WHERE TC 12S BEGINS TRACKING ALONG THE STR LOCATED TO THE EAST DUE TO THE LACK OF MODIFICATION BY TC 13S AS EXPECTED. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 190000Z IS 15 FEET.

SAWDOS Comment:  This is one of the weirdest tropical storms I have ever tracked.  Just look at the track this storm has followed since it developed in the Indian Ocean.  At one stage it appeared that the storm would  dissipate sometime this weekend but now it is once again a Cat. 1 cyclonic storm.  If it follows the predicted path in the next day or two it would be one of the weirdest storm patterns I have observed in the South Indian Ocean.  A question that comes to mind:   If the storm follows the predicted path, will it again move over eastern Madagscar?  This is not clear at this stage and it is important that we keep on monitoring this storm as TC 13S and the subtropical ridge over South Africa as well as the island of Madagascar could just have an influence on the current track of Cyclone Giovanna.  Observers should keep an eye on the weather in the Indian Ocean for any dramatic changes.