TC 08S(BATSIRAI) approaching the Mascarenes area and set to re-intensify// Invest 91W & Invest 97P up-dates, 28/15utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 08S(BATSRIAI) AND 3HOURLY SATELLITE BULLETINS ON 08S AND INVEST 91W.

28/14UTC.

3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 08S IS FORECAST TO TURN WEST-SOUTHWESTWARD AS THE SUBTROPICAL RIDGE (STR) WEAKENS IN RESPONSE TO AN APPROACHING MAJOR SHORTWAVE TROUGH. HOWEVER, THE TROUGH WILL QUICKLY PROPAGATE EASTWARD AND A WESTERN STR IS EXPECTED TO BUILD TO THE SOUTHWEST TURNING THE SYSTEM WEST-NORTHWESTWARD THROUGH 72H. POLEWARD OUTFLOW WILL IMPROVE AND ALLOW THE SYSTEM TO INTENSIFY TO 75 KNOTS/CAT 1 US BY 72H. AFTER 72H, THE STR WILL WEAKEN AND REALIGN PRODUCING A MORE WESTWARD TO WEST-SOUTHWESTWARD TRACK. ENVIRONMENTAL CONDITIONS WILL DEGRADE WITH INCREASING VERTICAL WIND SHEAR AND WEAK DIFFLUENCE, THEREFORE THE SYSTEM IS FORECAST TO GRADUALLY WEAKEN.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER THAT IS POSITIONED UNDER THE NORTHERN EDGE OF THE PRIMARY DEEP CONVECTIVE BAND. A 281213Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS A COMPACT SYSTEM WITH THE BULK OF THE CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI AND SSMIS IMAGE. THE INITIAL INTENSITY OF 45 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE FMEE DVORAK ESTIMATE AND THE CIMSS ADT ESTIMATE. ENVIRONMENTAL CONDITIONS REMAIN GENERALLY FAVORABLE WITH LOW VERTICAL WIND SHEAR AND MODERATE POLEWARD OUTFLOW.

MODEL DISCUSSION: THE JTWC FORECAST TRACK IS CONSISTENT WITH THE PREVIOUS FORECAST AND IS POSITIONED CLOSE TO THE ECMWF AND GFS SOLUTIONS. THERE IS A LARGE SPREAD IN BOTH DETERMINISTIC AND ENSEMBLE MODEL OUTPUT WITH SEVERAL MODELS (NAVGEM, UEMN AND AFUM) INDICATING A SHARP, UNREALISTIC POLEWARD TRACK AND THE REMAINING GUIDANCE INDICATING SIGNIFICANT UNCERTAINTY IN THE EXTENDED PERIOD FORECAST. RELIABLE INTENSITY GUIDANCE SUPPORTS THE INTENSIFICATION TREND THROUGH 72H WITH HWRF INDICATING A PEAK OF 80 KNOTS/CAT 1 US AT 60H. THE JTWC INTENSITY FORECAST IS SLIGHTLY HIGHER THAN THE JTWC INTENSITY CONSENSUS (ICNW) THROUGH 72H.

THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 11.5N 114.4E IS NOW LOCATED NEAR 12.4N 114.2E, APPROXIMATELY 775 KM WEST-SOUTHWEST OF MANILA, PHILIPPINES. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A BROAD CYCLONIC CIRCULATION TO THE EAST OF A PERSISTENT NORTHERLY SURGE. LARGE BURSTS OF DEEP CONVECTION EXIST TO THE NORTH AND SOUTH OF THE LOOSELY WRAPPED LOW LEVEL CIRCULATION CENTER (LLCC). A 280156Z MHS 89GHZ MICROWAVE IMAGE SHOWS DISORGANIZED DEEPER CONVECTIVE REGION DISPLACED TO THE NORTHEAST OF THE APPARENT CENTER. LOW LEVEL BANDING IS EVIDENT IN ALL QUADRANTS WITH THE MOST CONSOLIDATED TO THE WEST WITHIN THE SURGE EVENT AND TO THE NORTH NEAR THE CONVECTIVE BURST. ENVIRONMENTAL ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH CONVERGENCE ALOFT AND MID- LEVEL DRY AIR ENTRAINMENT OFFSET BY LOW VERTICAL WIND SHEAR VALUES (10-15KT). GLOBAL MODELS INDICATE THE SYSTEM WILL TRACK POLEWARD AND DISSIPATE WITHIN THE NEXT 36 TO 48 HOURS AS THE SYSTEM INTERACTS WITH A BAROCLINIC ZONE AND STRONG SUBTROPICAL WESTERLIES ALOFT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.

GLOBAL MODELS INDICATE THE SYSTEM WILL TRACK POLEWARD AND DISSIPATE WITHIN THE NEXT 36 TO 48 HOURS AS THE SYSTEM INTERACTS WITH A BAROCLINIC ZONE AND STRONG SUBTROPICAL WESTERLIES ALOFT.