WDXS31 PGTW 130300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 04S (CHIDO) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 11.1S 51.0E INITIAL INTENSITY: 115 KTS GEOGRAPHIC REFERENCE: 510 NM NORTH-NORTHEAST OF ANTANANARIVO, MADAGASCAR MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 49 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN INCREASINGLY RAGGED-LOOKING SYSTEM, WITH THE EYE NOW COMPLETELY FILLED AND DISORGANIZED CONVECTIVE CELLS SCATTERED HAPHAZARDLY AROUND THE CIRCULATION CENTER. THE CDO FEATURE IS RAPIDLY ERODING FROM THE EAST, AS THE LACK OF PERSISTENT DEEP CONVECTION ON THE UPSHEAR SIDE OF THE CIRCULATION HAS ALLOWED THE SHEAR TO PENETRATE CLOSER TO THE INNER CORE OF THE SYSTEM. A 130011Z SSMIS 91GHZ MICROWAVE IMAGE SHOWED A FULLY CLOSE EYEWALL, THOUGH IT WAS THINNEST ON THE EASTERN SIDE AND MORE WELL-DEVELOPED BANDING FEATURES STARTING TO FORM ON THE NORTHERN AND WESTERN PORTION OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION WAS ASSESSED WITH HIGH CONFIDENCE BASED ON THE MICROWAVE EYE FEATURE IN THE MICROWAVE IMAGE NOTED ABOVE. THE INITIAL INTENSITY WAS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED TOWARDS THE HIGHER END OF THE OBJECTIVE INTENSITY ESTIMATES NOTED ABOVE, AND THE T6.0 (115 KNOTS) CURRENT INTENSITY ESTIMATES FROM MULTIPLE AGENCIES. THE ENVIRONMENT IN AGGREGATE IS ASSESSED AS MARGINALLY FAVORABLE. WIND SHEAR REMAINS MODERATE TO HIGH FROM THE EAST, SSTS REMAIN WARM, AND THE CLOSER THE SYSTEM GETS TO MADAGASCAR MEANS THE MORE DISRUPTION TO THE INFLOW LAYER THAT CAN BE EXPECTED. UPPER-LEVEL OUTFLOW HOWEVER REMAINS ROBUST, THOUGH TIGHTLY CONFINED AROUND THE STORM ITSELF. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED NEAR THE MASCARENE ISLANDS. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS KNES: T6.0 - 115 KTS DEMS: T7.0 - 140 KTS FMEE: T6.0 - 115 KTS CIMSS SATCON: 115 KTS AT 121938Z CIMSS ADT: 102 KTS AT 130000Z CIMSS AIDT: 110 KTS AT 120000Z CIMSS D-MINT: 107 KTS AT 130010Z CIMSS D-PRINT: 108 KTS AT 130000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. JTWC HAS SHIFTED TO SIX-HOURLY WARNINGS EFFECTIVE 130000Z. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) O4S (CHIDO) WILL TRACK SOUTHWESTWARD ALONG THE NORTHWEST SIDE OF THE STR FOR THE ENTIRE DURATION OF THE FORECAST PERIOD. THE SYSTEM IS EXPECTED TO PASS ROUGHLY 20-30NM TO THE NORTH OF THE NORTHERN TIP OF MADAGASCAR OVER THE NEXT 12 HOURS, THEN TRACK VERY CLOSE TO MAYOTTE AND THE SOUTHERN ISLANDS OF COMOROS WITHIN THE NEXT 36 HOURS. LANDFALL ALONG THE NORTHEASTERN COAST OF MOZAMBIQUE, NORTH OF NACALA, IS ANTICIPATED WITHIN THE NEXT 48 TO 60 HOURS, THEN THE REMNANTS OF THE SYSTEM WILL MOVE ACROSS SOUTHERN MALAWI, AND INTO NORTHEASTERN ZIMBABWE BY THE END OF THE FORECAST. THE SYSTEM HAS WEAKENED ABOUT 10 KNOTS IN THE LAST SIX HOURS, AS EASTERLY SHEAR HAS FINALLY BEEN ABLE TO OVERCOME THE BLOCKING EFFECT OF THE UPSHEAR CONVECTION DEVELOPMENT. TC 04S IS FORECAST TO CONTINUE TO WEAKEN OVER THE NEXT 12 HOURS AS IT CONTINUES TO STRUGGLE AGAINST THE PERSISTENT SHEAR. THIS WILL BE TOUGH GOING AS THE SYSTEM WILL ALSO BE IMPACTED BY A DISRUPTION OF THE INFLOW FROM THE SOUTH DUE TO THE ELEVATED TERRAIN ALONG THE NORTHERN PORTION OF MADAGASCAR. HOWEVER, ONCE THE SYSTEM CLEARS THE NORTHWEST COAST, IT WILL MOVE INTO VERY WARM (30-31C) WATERS, AND TAP INTO A STRONG POLEWARD OUTFLOW CHANNEL. THE CURRENT FORECAST CALLS FOR THE SYSTEM TO MAINTAIN INTENSITY FROM TAU 12 THROUGH TAU 36, BUT IT IS POSSIBLE THAT THE SYSTEM COULD INTENSIFY A BIT THROUGH THIS TIME, ESPECIALLY IF IT REMAINS RELATIVELY INTACT AFTER PASSING NORTHERN MADAGASCAR. THE LANDFALL TIME CURRENTLY FALLS BETWEEN FORECAST POINTS, BUT INTENSITY AT LANDFALL IS EXPECTED TO BE NEAR 100 KNOTS. ONCE ASHORE THE SYSTEM WILL RAPIDLY WEAKEN AND DISSIPATE BY TAU 96. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN VERY GOOD AGREEMENT WITH THE TRACK ENVELOPE GRADUALLY EXPANDING TO 85NM AT LANDFALL. NAVGEM REMAINS THE POLEWARD EDGE MARKER WHILE THE GEFS ENSEMBLE MEAN IS THE EQUATORWARD EDGE MARKER. THE JTWC FORECAST TRACK IS CONSISTENT WITH THE MULTIMODEL CONSENSUS MEAN THROUGH THE ENTIRE FORECAST. INTENSITY GUIDANCE TELLS A SIMILAR STORY TO THE EARLIER RUNS, WITH THE HAFS-A AND COAMPS-TC CONTINUING TO SHOW A GENERALLY FLAT AND SLIGHTLY WEAKENING INTENSITY TREND THROUGH TAU 48, WHILE THE HWRF AND GFS SHOW A DRAMATIC AND RAPID WEAKENING FROM TAU 00 THROUGH THE REST OF THE FORECAST PERIOD. THE JTWC INTENSITY TREND LIES ON TOP OF THE HAFS-A FOR THE FIRST 48 HOURS OF THE FORECAST THEN LIES IN GENERAL ALONG THE CONSENSUS THOUGH WITH A SHALLOWER SLOPE THROUGH THE REMAINDER OF THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN