WDXS32 PGTW 260300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (GARANCE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.8S 52.9E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 212 NM NORTHWEST OF ST DENIS MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A STRENGTHENING SYSTEM, WITH ATTEMPTING TO DEVELOP AN IRREGULAR CENTRAL DENSE OVERCAST (CDO), BUT CURRENTLY STRUGGLING AGAINST PERSISTENT MODERATE SOUTHERLY SHEAR. THE CONVECTION IS RATHER DISORGANIZED WITH MULTIPLE DISJOINTED AREAS OF DEEP CONVECTIVE ACTIVITY. BASED ON A 252343Z SSMIS COLOR-ENHANCED 91GHZ MICROWAVE IMAGE, THE PRIMARY FOCUS OF THE VORTEX DEVELOPMENT APPEARS TO BE IN THE SOUTHWESTERN AREA OF CONVECTION. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE IN THIS REGION OF CONVECTION, BASED ON THE MICROWAVE IMAGE NOTED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED SLIGHTLY ABOVE THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES IN LIGHT OF THE HIGHER SATCON AND ADT ESTIMATES. THE ENVIRONMENT IS FAVORABLE AND IMPROVING, WITH VERY WARMS SSTS, GOOD EQUATORWARD OUTFLOW AND PLENTY OF MOISTURE, OFFSET FOR THE MOMENT BY THE PERSISTENT MODERATE SOUTHERLY SHEAR. INITIAL WIND RADII BASIS: PERSISTENCE WITH EARLIER SCATTEROMETER DATA. CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER NEAR EQUATORIAL RIDGE (NER) TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS KNES: T3.0 - 45 KTS FMEE: T3.0 - 45 KTS CIMSS SATCON: 51 KTS AT 252300Z CIMSS ADT: 49 KTS AT 260000Z CIMSS AIDT: 44 KTS AT 260000Z CIMSS D-MINT: 41 KTS AT 252140Z CIMSS D-PRINT: 37 KTS AT 252330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE EQUATORWARD 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. FORECAST DISCUSSION: TC 22S IS FORECAST TO CONTINUE TRACKING EASTWARD OVER THE NEXT 12 TO 18 HOURS, SLOWLY ARCING OVER TO A MORE SOUTHEASTWARD TRACK BY TAU 24, ALONG THE SOUTHERN SIDE OF THE NER TO THE NORTH. BY TAU 36, THE PRIMARY STEERING MECHANISM SHIFTS TO THE NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) TO THE EAST, CAUSING TC 22S TO ACCELERATE SOUTHWARD AFTER THIS POINT. THE SYSTEM IS EXPECTED TO PASS DIRECTLY OVER, OR VERY NEAR TO THE ISLAND OF LA REUNION AROUND TAU 48, BEFORE PICKING UP ADDITIONAL SPEED AS IT CONTINUES POLEWARD. THE SYSTEM WILL ROUND THE RIDGE AXIS AROUND TAU 72 THEN TURN GRADUALLY SOUTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN TERMS OF INTENSITY, THE SYSTEM IS STARTING TO DEVELOP UPSHEAR CONVECTION AND LOOKS TO BE SETTING THE STAGE FOR POTENTIAL RAPID INTENSIFICATION (RI) WITHIN THE NEXT 12 TO 24 HOURS. IN ALL LIKELIHOOD, THE PACE OF INTENSIFICATION WILL BE RELATIVELY SLOW FOR THE NEXT 12 HOURS AS THE SYSTEM CONTINUES TO SYMMETRIZE. ENVIRONMENTAL SHEAR IS FORECAST TO DROP OFF AFTER TAU 12, WHICH WILL ALLOW FOR RI THEREAFTER. CONDITIONS WILL BE HIGHLY FAVORABLE TO RI FROM TAU 12 UP THROUGH TAU 48, OR JUST PRIOR TO PASSAGE OVER OR NEAR LA REUNION. THE FORECAST CALLS FOR A PEAK OF 100 KNOTS BY TAU 36, CARRYING THROUGH TAU 48, THOUGH THE ACTUAL PEAK MAY BE SLIGHTLY HIGHER AS INDICATED BY SOME OF THE RI GUIDANCE. THE SOONER THE SYSTEM ACHIEVES SYMMETRIZATION, THE HIGHER THE PEAK INTENSITY WILL BE. AFTER PASSING LA REUNION, CONDITIONS RAPIDLY DETERIORATE WITH SOUTHEASTERLY SHEAR EXPECTED TO QUICKLY INCREASE TO MORE THAN 40 KNOTS BY TAU 72, INCREASING FURTHER THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE SYSTEM WILL BEGIN SUBTROPICAL TRANSITION (STT) BY TAU 120 AS IT MOVES UNDER THE SUBTROPICAL WESTERLIES AND COOL OCEAN WATERS. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72. CROSS-TRACK SPREAD AT CPA TO LA REUNION IS 85NM, OPENING UP TO 150NM BY TAU 72. GFS AND THE GEFS MEAN TAKE THE INSIDE TRACK, AND MARK THE WESTERN SIDE OF THE GUIDANCE ENVELOPE WHILE UKMET AND THE UKMET ENSEMBLE MEAN TAKE A BROADER TURN AND MARK THE EASTERN EDGE OF THE ENVELOPE. CROSS-TRACK SPREAD OPENS UP TO 350NM BY THE END OF THE FORECAST. THE JTWC FORECAST TRACKS THE ECMWF AND CONSENSUS MEAN THROUGH THE TOTALITY OF THE FORECAST PERIOD, WITH HIGH CONFIDENCE IN THE SHORT-TERM AND MEDIUM CONFIDENCE THEREAFTER. INTENSITY GUIDANCE, WITH THE EXCEPTION OF THE SHIPS-GFS, IS IN TIGHT AGREEMENT THAT THE SYSTEM IS LIKELY TO RI. ALL OF THE MESOSCALE GUIDANCE, AND NEARLY ALL AVAILABLE RI SPECIFIC AIDS ARE DEPICTING A RAPID INTENSIFICATION TO A PEAK BETWEEN 95-115 KNOTS BY TAU 36. ADDITIONALLY, THE ECEPS INTENSIFICATION PROBABILITY GUIDANCE INDICATES A 40 PERCENT CHANCE OF RI, WHICH IS NEARLY UNHEARD OF FROM ECEPS. IN OTHER WORDS, CONFIDENCE IS HIGH THAT RI WILL OCCUR. MOST OF THE GUIDANCE SHOWS A LEVELING OFF OF INTENSITY THROUGH TAU 48, FOLLOWED BY A RAPID WEAKENING PHASE THROUGH THE REMAINDER OF THE FORECAST. THE JTWC FORECAST TRACKS THE BULK OF THE RI GUIDANCE BUT PEAKS ABOUT 5-15 KNOTS LOWER THAN THE MOST AGGRESSIVE MEMBERS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN