TC 13S(EMNATI): crossing Southern Madagascar & then over the MOZ Channel// Invest 98P: now on the map,23/09utc

JTWC IS ISSUING 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 13S(EMNATI).

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 13S WILL CONTINUE ON ITS CURRENT SOUTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR AND EXIT INTO THE MOZAMBIQUE CHANNEL JUST BEFORE 12H. AFTER 24H, IT WILL TRACK MORE SOUTHWARD AS IT ROUNDS THE WESTERN EDGE OF THE SUBTROPICAL RIDGE (STR). INTERACTION WITH THE RUGGED TERRAIN, THEN THE COOLER (24C) SST AND STRONG (30KT+) VWS, OFFSET BY STRONG POLEWARD OUTFLOW IN THE MOZAMBIQUE CHANNEL WILL RESULT IN GRADUAL DECAY - DOWN TO 45KTS BY TAU 48. CONCURRENTLY BY 36H, TC 13S WILL BEGIN SUBTROPICAL TRANSITION AND BY 48H, WILL TRANSFORM INTO A SUBTROPICAL SYSTEM WITH AN EXPANDING WIND FIELD.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MADE LANDFALL OVER SOUTH CENTRAL MADAGASCAR. THE CENTRAL CONVECTIVE TOPS HAVE SIGNIFICANTLY WARMED AND COLLAPSED AS IT ENCOUNTERED THE RUGGED TERRAIN. HOWEVER, REMNANTS OF THE EYEWALL REMAIN VISIBLE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE REMNANT EYEWALL THAT LINED UP WELL WITH A PARTLY OBSCURE LOW LEVEL MICROWAVE EYE FEATURE IN THE 230302Z SSMIS 91GHZ IMAGE. THE INITIAL INTENSITY IS EXTRAPOLATED FROM DVORAK ESTIMATES PRIOR TO LANDFALL AND REFLECTS THE 6-HR DECAY. ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH LOW VWS AND MODERATE RADIAL OUTFLOW OFFSET BY FRICTIONAL EFFECTS OF THE RUGGED TERRAIN. TC 13S IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST.

MODEL DISCUSSION: NUMERICAL MODELS ARE GENERALLY IN GOOD AGREEMENT WITH A GRADUAL SPREAD TO 255 KM BY 48H. HOWEVER, DUE TO THE UNCERTAINTY OF A LAND PASSAGE, THERE IS OVERALL MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.

AN AREA OF CONVECTION (INVEST 98P) HAS PERSISTED NEAR 10.5S 139.7E, APPROXIMATELY 345 KM NORTHWEST OF WEIPA, AUSTRALIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A WEAKLY- DEFINED LOW LEVEL CIRCULATION (LLC) WITH FLARING CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE DEVELOPMENT FOR TROPICAL CYCLONE FORMATION WITH LOW (10-15KT) VERTICAL WIND SHEAR, MODERATE POLEWARD OUTFLOW, AND VERY WARM (30-31C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL CONTINUE TO TRACK EASTWARD AND DEVELOP WITHIN THE NEXT 48-72HRS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1010 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO LOW.

GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL CONTINUE TO TRACK EASTWARD AND DEVELOP WITHIN THE NEXT 48-72HRS.