TC 08S(BATSIRAI):over-land:Mananjary(Madagascar)reported very high winds//TC 10S(CLIFF) still surviving//Invest 92P and Invest 93S,06/03utc

JTWC IS ISSUING 12HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 08S(BATSIRAI) AND TC 10S(CLIFF).

06/01UTC.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 08S IS BEING STEERED TO THE WEST-SOUTHWEST ALONG THE NORTHWESTERN PERIPHERY OF A DEEP SUBTROPICAL (STR) TO THE SOUTH, AT A SPEED OF ROUGHLY 22 KM/H. SOME ADDITIONAL SLOWING CAN BE EXPECTED IN THE NEAR-TERM, BUT ONCE THE SYSTEM CROSSES THE RIDGE OF THE MOUNTAIN RANGE, IT WILL LIKELY PICK UP SPEED AS IT TRACKS TOWARDS THE WEST COAST OF MADAGASCAR. AS THE SYSTEM CROSSES THE ISLAND, LOW LEVEL FLOW DISRUPTION AND FRICTIONAL EFFECTS WILL LEAD TO CONTINUED WEAKENING. TC 08S IS EXPECTED TO REEMERGE INTO THE MOZAMBIQUE CHANNEL WITHIN THE NEXT 18-24 HOURS AT A GREATLY REDUCED INTENSITY OF NEAR 40 KNOTS. THE SYSTEM IS EXPECTED TO REACH THE AXIS OF THE STEERING RIDGE BY 36H AND SLOW DOWN UNDER A WEAKENED STEERING FLOW, THEN ACCELERATE POLEWARD AFTER 48H AS IT ROUNDS THE RIDGE AXIS. CONDITIONS WILL BE MARGINALLY FAVORABLE AS THE SYSTEM MOVES INTO THE CHANNEL, WITH WARM (27-28C) WATERS AND ENHANCED POLEWARD OUTFLOW OFFSETTING MODERATE SHEAR FOR ABOUT 24 HOURS, ALLOWING FOR AN INTENSIFICATION TO 50 KNOTS. INCREASING SHEAR AND DRY AIR WILL BEGIN TO OVERWHELM TO EFFECT OF THE ENHANCED OUTFLOW AFTER 48H, LEADING TO A STEADY WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST PERIOD. TC 08S WILL BEGIN SUBTROPICAL TRANSITION BY 72H AS IT CROSSES THE 26C ISOTHERM AND BEGINS TO MOVE UNDER A MID-LEVEL LOW. SUBTROPICAL TRANSITION IS EXPECTED BY 96H AS SSTS DROP BELOW 24C AND THE SYSTEM BECOMES EMBEDDED IN THE UPPER-LEVEL WESTERLY FLOW.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TC 08S MADE LANDFALL ALONG THE COAST OF MADAGASCAR, JUST NORTH OF THE TOWN OF MANANJARY, AROUND 051700Z. AS THE SYSTEM WAS MAKING LANDFALL, THE EYE SHRUNK DOWN FROM 45-KM TO LESS THAN 22-KM, WHILE CLOUD TOP TEMPERATURES FELL TO -80C OR COLDER AND THE LAST OBSERVATION FROM MANANJARY AT 051500Z INDICATED SUSTAINED 10-MIN WINDS OF 90 KNOTS. HENCE, THE 051800Z INTENSITY WAS HELD AT 100 KNOTS THROUGH THE LANDFALL EVENT. SUBSEQUENTLY THE SYSTEM HAS MOVED OVER THE RUGGED TERRAIN OF SOUTH-CENTRAL MADAGASCAR AND BEGUN TO RAPIDLY WEAKEN. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RAPIDLY ERODING STRUCTURE, WITH DRAMATICALLY WARMER CLOUD TOP TEMPERATURES AND WEAK, FRAGMENTED BANDING. THE LACK OF RECENT MICROWAVE IMAGERY, SURFACE OBSERVATIONS OR RADAR DATA LEND ONLY LOW CONFIDENCE TO THE INITIAL POSITION. WITH THE POSITION OVER LAND, THERE ARE NO DVORAK-BASED INTENSITY ESTIMATES AND NEARBY SURFACE OBSERVATION POINTS ARE NOT REPORTING AT THIS TIME, THEREFORE THE INITIAL INTENSITY IS BASED STRICTLY OFF EXPECTED OR MODELED WEAKENING OVER COMPLEX TERRAIN, WITH LOW CONFIDENCE.

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL SCENARIO, AND EXHIBITS A 250KM SPREAD AT 72H, INCREASING TO 280KM AT 96H. WHILE CROSS-TRACK SPREAD IS MINIMAL, ALONG-TRACK SPREAD INCREASES SIGNIFICANTLY AFTER 72H, UP TO 1110KM BETWEEN OUTLIERS. THE JTWC FORECAST LIES ON THE RIGHT SIDE OF THE GUIDANCE PACKAGE THROUGH 24H, THEN JUST WEST OF THE CONSENSUS MEAN THROUGH 72H WITH HIGH CONFIDENCE. THE INCREASED ALONG-TRACK SPREAD AFTER 72H LENDS MEDIUM CONFIDENCE TO THAT PORTION OF THE TRACK FORECAST. INTENSITY GUIDANCE IS IN STRONG AGREEMENT WITH THE SYSTEM EMERGING INTO THE CHANNEL AT 40 KNOTS, FOLLOWED BY A REINTENSIFICATION TO A PEAK BETWEEN 45-55 KTS. THE JTWC FORECAST LIES CLOSE TO THE CONSENSUS MEAN IN THE EARLY TAUS, THEN JUST BELOW THE HWRF PEAK THROUGH THE REMAINDER OF THE FORECAST.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: AS TC 10S HAS WEAKENED, THE PRIMARY STEERING MECHANISM HAS SHIFTED OVER TO THE LOW TO MID-LEVEL SUBTROPICAL RIDGE (STR) TO THE SOUTH AND TC 10S HAS TURNED SHARPLY WESTWARD IN THE LAST 6-12 HOURS. NO SIGNIFICANT CHANGE IS EXPECTED IN THIS TRACK THROUGH THE FORECAST PERIOD. THE PRESENCE OF LOW TO MID-LEVEL STABLE, DRY AIR, AS REVEALED BY THE LARGE STRATOCUMULUS FIELD TO THE SOUTH, IS BEING WRAPPED INTO THE CORE OF THE SYSTEM. COMBINED WITH MODERATE AND INCREASING NORTHERLY SHEAR, AND STEADILY DECREASING SSTS, TC 10S IS FORECAST TO STEADILY, IF SOMEWHAT SLOWLY, WEAKEN OVER THE NEXT 36 HOURS, DIPPING BELOW WARNING THRESHOLD NO LATER THAN 36H.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), WITH THE NORTHERN HEMISPHERE EXPOSED AND THE SOUTHERN HEMISPHERE OBSCURED BY AN AREA OF SYMMETRICAL FLARING CONVECTION. A 051620Z GMI COLOR COMPOSITE MICROWAVE IMAGE SHOWS THE DISORGANIZED AND INCREASINGLY ELONGATED LLCC, DEVOID OF SIGNIFICANT CONVECTIVE ACTIVITY AND AN AREA OF ENHANCED CONVECTION SHEARED TO THE SOUTH. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED EIR AND MICROWAVE IMAGERY. RECENT L-BAND RADIOMETER BASED WIND ESTIMATES FROM BOTH SMAP AND SMOS INDICATE AN ASYMMETRIC WIND FIELD, WITH 20-30 KNOT WINDS IN THE NORTHERN HEMISPHERE AND A BROAD SWATH OF 35-40 KNOT WINDS TO THE SOUTH. THE INITIAL INTENSITY IS THUS SET AT 35 KNOTS, SLIGHTLY ABOVE THE PGTW T2.0 DVORAK ESTIMATE AND THE ADT OF T2.1. WHILE THE SYSTEM IS OBVIOUSLY SHEARED, THE AMOUNT OF SHEAR IS IN QUESTION WITH THE CIMSS ANALYSIS INDICATING 5-10 KNOTS, WHILE HWRF AND GFS AREA AVERAGE SKEW-T ANALYSES REVEAL SHEAR MORE IN THE RANGE OF 15-20 KNOTS. BASED ON THE SATELLITE DEPICTION, THE HIGHER SHEAR VALUES ARE LIKELY MORE CORRECT.

MODEL DISCUSSION: WITH THE CONTINUED EXCEPTION OF NAVGEM, WHICH REMAINS AN UNREALISTIC POLEWARD SIDE OUTLIER, THE BULK OF THE TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, SUPPORTING THE JTWC FORECAST WITH HIGH CONFIDENCE. SIMILARLY, ALL OF THE INTENSITY GUIDANCE INDICATES SLOW BUT STEADY WEAKENING THROUGH THE PERIOD, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST INTENSITY.

THE AREA OF CONVECTION (INVEST 92P) PREVIOUSLY LOCATED NEAR 17.7S 153.2E IS NOW LOCATED NEAR 18.4S 160.0E, APPROXIMATELY 890KM WEST OF PORT VILA, VANUATU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY CONTINUES TO DEPICT A POORLY-ORGANIZED AND ELONGATED DISTURBANCE EMBEDDED WITHIN A WEST-NORTHWEST TO EAST-SOUTHEAST ORIENTED FRONTAL TROUGH. A 060252Z AMSR2 36GHZ COLOR COMPOSITE MICROWAVE IMAGE REVEALS NO DISCERNIBLE LOW-LEVEL CIRCULATION WITH HIGHLY DISORGANIZED SHALLOW BANDS OF CONVECTION ACROSS THE CORAL SEA. THE DISTURBANCE IS LOCATED WITHIN MODERATE NORTHWESTERLY FLOW ALONG THE SOUTHWESTERN PERIPHERY OF AN UPPER-LEVEL RIDGE. VERTICAL WIND SHEAR REMAINS LOW TO MODERATE WITH WARM SEA SURFACE TEMPERATURES OF 29-30 DEGREES CELSIUS. THE DISTURBANCE IS EXPECTED TO TRACK EAST-SOUTHEASTWARD TOWARD VANUATU ALONG THIS FRONTAL BOUNDARY FOR THE NEXT 12 HOURS WITHIN A MARGINALLY FAVORABLE ENVIRONMENT. WITHIN THE NEXT 12 TO 24 HOURS, NUMERICAL MODELS GENERALLY AGREE THAT SOME DEVELOPMENT WILL OCCUR AS THE DISTURBANCE TRACKS UNDER A MORE FAVORABLE UPPER-LEVEL ENVIRONMENT BENEATH THE BROAD UPPER-LEVEL RIDGE. THIS ZONE WILL BE MONITORED CLOSELY, AS A COMPLEX ENVIRONMENT COULD LEAD TO MULTIPLE CIRCULATIONS FORMING IN CLOSE PROXIMITY WITHIN THE SOUTH PACIFIC CONVERGENCE ZONE IN THE GENERAL VICINITY OF NEW CALEDONIA, VANUATU, FIJI, AND TONGA DURING THE NEXT SEVERAL DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 999 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW