TC 19S(GOMBE): inland over MOZ, forecast to be back over open sea shortly after 48h//Invest 90S: up-graded to Medium,12/09utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 19S(GOMBE). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON 19S AND INVEST 90S.

12/0815UTC.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE EXTENDED FORECAST INTENSITIES OVER THE MOZAMBIQUE CHANNEL HAS BEEN INCREASED TO ABOVE 35 KTS; OTHERWISE, THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 19S IS STRUGGLING TO REMAIN INTACT AS IT MOVES OVER THE RUGGED TERRAIN OF MOZAMBIQUE. TC 19S IS EXPECTED TO RECURVE TO THE SOUTHWEST AS IT BEGINS ROUNDING THE FAR WESTERN EDGE OF THE SUBTROPICAL RIDGE (STR) AXIS TO THE EAST-SOUTHEAST THROUGH THE NEXT 36-48 HOURS. BY 48H, OR SLIGHTLY AFTER, TC 19S IS EXPECTED TO REGAIN ITS MOISTURE SOURCE AS IT ENTERS BACK OVER THE MOZAMBIQUE CHANNEL NEAR QUELIMANE AS A WEAK TROPICAL DEPRESSION AND THEN WILL REGAIN INTENSITY TO TROPICAL STORM STRENGTH OVER THE NEXT 72-120 HOURS.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED LOW-LEVEL CIRCULATION (LLC) THAT HAS CONTINUED TO UNRAVEL AND WEAKEN IN INTENSITY. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE AS THE LLC IS OBSCURED BY MID AND HIGH-LEVEL CLOUDS. VERY LITTLE CONVECTION REMAINS WITH TC 19S ON THE EASTERN AS INDICATED USING THE 120415Z SSMIS 89GHZ IMAGE. THE INITIAL INTENSITY OF 30KTS IS ASSESSED WITH LOW CONFIDENCE DUE TO A LACK OF OBJECTIVE AND SUBJECTIVE AIDS DUE TO THE SYSTEM REMAINING OVERLAND. THE OVERALL CONVECTIVE STRUCTURE HAS CONTINUED TO UNRAVEL OVER THE RUGGED TERRAIN OF MOZAMBIQUE. ALTHOUGH THE LOW (5-10KT) VWS AND UPPER-LEVEL OUTFLOW ARE BOTH FAVORABLE, THE LACK OF A MOISTURE SOURCE AND TERRAIN INFLUENCE DECREASE THE OVERALL ENVIRONMENT TO UNFAVORABLE. TC 19S WILL CONTINUE TRACKING ALONG THE NORTHWEST PERIPHERY OF THE STR TO THE SOUTHEAST.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN BROAD AGREEMENT WITH THE TRACK UP TO THE FIRST 36 TO 48 HOURS. AFTERWARD, THE MODELS BEGIN TO DIVERGE SIGNIFICANTLY, AS THE SYSTEM EXITS THE COAST NEAR QUELIMANE AND THE MOUTH OF RIO ZAMBEZE INTO THE WARM WATERS OF THE MOZAMBIQUE CHANNEL. A BIFURCATION BEGINS TO FORM AT 72H WITH GFS, AFUM, AND UEMN MOVING THE SYSTEM TO THE NORTHEAST, WHILE THE REST OF THE MODELS AND ECMF ENSEMBLES MOVE THE SYSTEM SOUTHWEST. THE INTENSITY GUIDANCE IS ALSO LIMITED AS A RESULT OF THE WEAK VORTEX BEFORE IT REEMERGES OVER THE CHANNEL. HWRF SHOWS THE EXTREME OF 115KTS AS IT INDICATES A POSSIBLE RAPID INTENSIFICATION SCENARIO BY 108H, WHILE COTC IS ONLY EXPECTING THE SYSTEM TO REMAIN UNDER 25KTS FOR THE DURATION OF THE FORECAST. DUE TO THIS UNCERTAINTY, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.

THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR 11.1S 110.1E IS NOW LOCATED NEAR 10.8S 108.9E, APPROXIMATELY 350 KM EAST OF CHRISTMAS ISLAND. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY AND A 120435Z 89GHZ PASS REVEALS CONSOLIDATING CONVECTION OVERHEAD A LOW LEVEL CIRCULATION. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT DEFINED BY; STRONG RADIAL OUTFLOW ALOFT, LOW TO MODERATE (10-15KT) VERTICAL WIND SHEAR, AND WARM (28-29C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT INVEST 90S WILL GENERALLY TRACK WEST- SOUTHWESTWARD, HOWEVER THEY ARE SPLIT ON INTENSIFICATION WITH ECMWF SHOWING SLOWER DEVELOPMENT OVER THE NEXT 24-48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

GLOBAL MODELS ARE IN GOOD AGREEMENT THAT INVEST 90S WILL GENERALLY TRACK WEST- SOUTHWESTWARD, HOWEVER THEY ARE SPLIT ON INTENSIFICATION WITH ECMWF SHOWING SLOWER DEVELOPMENT OVER THE NEXT 24-48 HOURS.