TC 19S(GOMBE): slowly pushing inland, heavy-rain maker,forecast back over open ocean in 72h//Invest 90S and Invest 99S, 11/09utc

JTWC HAS BEEN ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 19S(GOMBE). WARNING FREQUENCY WILL SHIFT TO 12HOURLY FROM NOW ON.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING, HOWEVER THE FORECAST FREQUENCY HAS BEEN SHIFTED TO 12-HOURLY. FORECAST DISCUSSION: WHILE THE GENERAL TRACK OF TC 19S HAS BEEN TOWARDS THE WEST-NORTHWEST, IT APPEARS TO HAVE TAKEN A BIT OF MORE NORTHWESTWARD TRACK IN THE SIX HOURS SINCE LANDFALL. BUT THE OVERALL STEERING MECHANISM, THE STRONG SUBTROPICAL RIDGE (STR) TO THE SOUTH, REMAINS UNCHANGED AT THIS TIME AND THE SYSTEM IS FORECAST TO TURN ONTO A MORE WESTWARD TRACK IN THE NEAR-TERM EXTENDING THROUGH 36H. BY 36H THE SYSTEM WILL SLOW DOWN AS IT MOVES INTO A COMPLEX UPPER-LEVEL STEERING PATTERN WITH A NEAR-EQUATORIAL RIDGE (NER) TO THE NORTHEAST COMPETING WITH THE STR TO THE SOUTH. BY 48H A BUILDING NORTH-SOUTH ORIENTED RIDGE WILL BECOME THE DOMINANT STEERING MECHANISM AND THE REMNANTS OF TC 19S WILL TURN SHARPLY SOUTH-SOUTHEASTWARD WHILST ACCELERATING TOWARDS THE COASTLINE. THE SYSTEM IS EXPECTED TO REEMERGE OVER WATER SHORTLY BEFORE 72H, AND EVENTUALLY WILL SLOW AND TURN SOUTHWARD BY 120H AS IT ONCE AGAIN ENCOUNTERS A WEAK STEERING PATTERN. NOW THAT THE SYSTEM IS OVER LAND IT IS EXPECTED TO RAPIDLY WEAKEN, DOWN TO 30 KNOTS BY 36H. THE ENVIRONMENT IS FORECAST TO REMAIN VERY MOIST EVEN WHILE OVER LAND, WITH MODERATE LEVELS OF OUTFLOW ALOFT, WHICH WILL ENCOURAGE CONTINUED THUNDERSTORM ACTIVITY AND HEAVY RAINFALL FOR THE DURATION OF THE SYSTEM BEING OVER LAND. THE REMAINS OF TC 19S ARE EXPECTED TO REEMERGE OVER THE MOZAMBIQUE CHANNEL BY 72H, ENCOUNTER WARM SSTS, LOW VWS AND STRONG POLEWARD OUTFLOW INTO THE BASE OF A MID-LATITUDE TROUGH, AND WILL QUICKLY RECONSOLIDATE AND INTENSIFY TO A PEAK OF 50 KNOTS BY 120H. THERE REMAINS A SMALL POSSIBILITY THAT THE SYSTEM WILL TRACK FURTHER INLAND AND DISSIPATE FULLY, BUT THIS SCENARIO IS ASSESSED AS UNLIKELY AT THIS TIME.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TC 19S MADE LANDFALL ALONG THE COAST OF MOZAMBIQUE AROUND THE 110000Z HOUR, JUST SOUTH OF NACALA. A RAGGED EYE HAD FORMED JUST PRIOR TO LANDFALL BUT SUBSEQUENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A RAPID DETERIORATION AND DISAPPEARANCE OF THE EYE STRUCTURE, AND WARMING CLOUD TOP TEMPERATURES. A 110219Z SSMIS 91GHZ MICROWAVE IMAGE SHOWED A VERY WELL DEFINED MICROWAVE EYE FEATURE WITH A STRONG EYEWALL IN ALL QUADRANTS EXCEPT THE WESTERN SIDE, WHICH WAS ERODED DUE TO LAND INTERACTION. THE INITIAL POSITION IS ASSESSED IS BASED ON THE CENTER FIXES FROM PGTW AND FMEE, WITH MEDIUM CONFIDENCE DUE TO THE LACK OF AN EYE FEATURE. THE INITIAL INTENSITY OF 80 KNOTS/CAT 1 US IS ASSESSED WITH LOW CONFIDENCE DUE TO THE LACK OF OVER LAND SATELLITE INTENSITY ESTIMATES AND IS BASED PRIMARILY ON A STANDARD RATE OF OVER LAND WEAKENING.

MODEL DISCUSSION: THE NEW GUIDANCE PACKAGE, INCLUDING BOTH DETERMINISTIC AND ENSEMBLE GUIDANCE, HAS NOT CHANGED SIGNIFICANTLY FROM THE PREVIOUS. THE NAVGEM AND GALWEM SOLUTIONS CONTINUE TO SHOW THE CIRCULATION REMAINING OVER LAND THROUGH THE FORECAST PERIOD AND FULLY DISSIPATING. THE REMAINDER OF THE GUIDANCE PACKAGE SUPPORTS THE JTWC FORECAST TRACK, WITH EGRR REPRESENTING THE WESTERN SIDE OF THE ENVELOPE AND THE GFS AND GEFS ENSEMBLE MEAN REPRESENTING THE EASTERN BOUNDARY. THE JTWC TRACK IS SLIGHTLY FURTHER WEST THAN THE PREVIOUS RUN, BUT STILL ALONG THE EASTERN HALF OF THE ENVELOPE AND JUST EAST OF THE CONSENSUS MEAN WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT UNTIL 72H WHEN THE SYSTEM IS FORECAST TO ONCE AGAIN EMERGE OVER WATER. THE JTWC FORECAST LIES JUST ABOVE MEAN THROUGH 72H WITH HIGH CONFIDENCE. IN THE EXTENDED RANGE, THERE IS A LARGE SPREAD IN MODEL SOLUTIONS, WITH THE HWRF INDICATING A PEAK OF 65 KNOTS WHILE THE GFS PEAKS AT 95 KNOTS WITH THE REMAINDER CLUSTERED BETWEEN 35-45 KNOTS. COAMPS-TC ENSEMBLE INTENSITY GUIDANCE SUGGESTS A MODERATE PROBABILITY OF MODERATE INTENSIFICATION AND LOW PROBABILITY OF RAPID INTENSIFICATION AFTER 96H. THE JTWC EXTENDED RANGE FORECAST LIES CLOSE TO THE CONSENSUS MEAN WITH LOW CONFIDENCE DUE TO THE VERY WIDE SPREAD IN THE DETERMINISTIC AND ENSEMBLE SOLUTIONS AND THE POSSIBILITY OF A DISSIPATION SCENARIO.