TC 11S(FREDDY) to re-intensify at CAT 4 US approaching the Mascarenes//Invest 99W up-graded//Invest 92S//Invest 93S//1815utc update

JTWC IS ISSUING 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 11S(FREDDY).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RECOVERING SYSTEM THAT PREVIOUSLY UNDERWENT A SMALL PERIOD OF DETERIORATION. TC FREDDY IS BEGINNING TO RESHAPE BACK INTO A SYMMETRICAL SYSTEM AND NOW HAS A CLOUD FILLED EYE. A MICROWAVE EYE IS PRESENT IN THE 180921Z AMSR2 89GHZ IMAGE INDICATING A BETTER STRUCTURE THAN THE PREVIOUS FORECAST. ANALYSIS OF THE HIGH RESOLUTION GFS AND HWRF MODELS INDICATES THE DRY AIR THAT WAS PREVIOUSLY AFFECTING THE MID-LEVELS IS BEGINNING TO GIVE WAY TO INCREASING MOISTURE. ENVIRONMENTAL ANALYSIS INDICATES TC 11S TO BE IN FAVORABLE CONDITIONS FOR CONTINUAL TROPICAL DEVELOPMENT. THESE CONDITIONS ARE CHARACTERIZED BY CONSISTENT WESTERLY OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), A VERY STRONG 850 MB VORTICITY SIGNATURE, AND WARM (27-28 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE ABOVE MENTIONED MSI AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A BLEND OF MULTI-AGENCY AND AUTOMATED DVORAK ESTIMATES.

MICROWAVE EYE INDICATING AN IMPROVING STRUCTURE.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC FREDDY CONTINUES ITS WEST-SOUTHWESTWARD TRACK AS IT TRANSITS THE NORTHERN PERIPHERY OF THE STR TO THE SOUTH. THE SYSTEM WILL CONTINUE THIS TRAJECTORY AND GRADUALLY INCREASE IN INTENSITY TO 120 KNOTS BY TAU 48 DUE TO ENTERING AN IMPROVING ENVIRONMENT. COPIOUS AMOUNTS OF DRY AIR WILL CONTINUE TO SURROUND THE SYSTEM, HOWEVER, TC FREDDY WILL STAY COCOONED IN ITS OWN MOISTURE POCKET DURING ITS FORECAST TRACK. TC 11S IS FORECAST TO MAKE LANDFALL ON THE EAST COAST OF MADAGASCAR AFTER TAU 72 AND DECREASE IN INTENSITY TO 50 KNOTS BY TAU 96 DUE TO LAND INTERACTION. BY TAU 120, THE SYSTEM IS FORECAST TO RE-INTENSIFY AS IT TRANSITS OVER THE MOZAMBIQUE CHANNEL.

MODEL DISCUSSION: THE JTWC MODEL TRACK CONSENSUS REMAINS IN TIGHT AGREEMENT WITH A GRADUAL SPREAD TO 80 NM BY TAU 48. AFTERWARDS, THE SPREAD INCREASES TO 325 NM BY TAU 120 AS THE MEMBERS DISAGREE WITH THE TRAJECTORY AFTER LANDFALL. GFS DETERMINISTIC AND ENSEMBLE GUIDANCE TAKES TC 11S ON A MORE WEST-NORTHWESTWARD TRACK AFTER CROSSING OVER THE MOZAMBIQUE CHANNEL, WHEREAS THE OTHER MEMBERS KEEP THE SYSTEM ON A WEST-SOUTHWESTWARD TRACK. THE FORECAST TRACK IS SET SLIGHTLY TO THE RIGHT OF CONSENSUS AFTER TAU 72 TO ACCOUNT FOR THE OFFSET OF THE GFS GUIDANCE. BECAUSE OF THIS, THE JTWC FORECAST TRACK IS PLACED WITH HIGH CONFIDENCE UP TO TAU 72, THEN MEDIUM CONFIDENCE THEREAFTER. THE INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT WITH THE EXCEPTION OF GFS WHICH DECREASES THE INTENSITY WELL BEYOND THE OTHER CONSENSUS MEMBERS. THE JTWC INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE THROUGHOUT THE FORECAST PERIOD.

THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 7.7N 131.8E IS NOW LOCATED NEAR 7.2N 129.3E, APPROXIMATELY 220 NM EAST OF DAVAO, PHILIPPINES. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 172212Z GMI 89GHZ MICROWAVE PASS REVEAL AN AREA OF BROAD AND DISORGANIZED CONVECTION, GRADUALLY CONSOLIDATING INTO A LOW-LEVEL CIRCULATION (LLC) ALONG AN ELONGATED TROUGH AXIS. A 180033Z ASCAT-B BULLSEYE SCATTEROMETRY PASS DEPICTS A LOCALIZED REGION OF 25-30KT WINDS CONCENTRATED WITHIN THE SOUTHEASTERN EDGE OF AN ELONGATED TROUGH. ENVIRONMENTAL ANALYSIS SHOWS THAT 99W IS IN A FAVORABLE AREA FOR DEVELOPMENT AS SUPPORTED BY GOOD POLEWARD OUTFLOW CHANNELS, LOW (05-10KT) VWS, AND WARM (28-29C) SSTS. DETERMINISTIC MODELS AND A MAJORITY OF ENSEMBLE MEMBERS ARE IN AGREEMENT THAT THIS CIRCULATION WILL CONTINUE ALONG A NORTH-NORTHWESTERN TRAJECTORY ALONG THE EAST COAST OF THE PHILIPPINES AND WILL CONSOLIDATE TO A MORE ORGANIZED CIRCULATION OVER THE NEXT 48-72 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 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.

DETERMINISTIC MODELS AND A MAJORITY OF ENSEMBLE MEMBERS ARE IN AGREEMENT THAT THIS CIRCULATION WILL CONTINUE ALONG A NORTH-NORTHWESTERN TRAJECTORY ALONG THE EAST COAST OF THE PHILIPPINES AND WILL CONSOLIDATE TO A MORE ORGANIZED CIRCULATION OVER THE NEXT 48-72 HOURS.