WDPN32 PGTW 241500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (GAEMI) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 23.7N 121.7E INITIAL INTENSITY: 110 KTS GEOGRAPHIC REFERENCE: 85 NM SOUTH OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 40 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: AS DEPICTED IN ANIMATED RADAR IMAGERY, TYPHOON (TY) 05W HAS TRACKED ERRATICALLY OVER THE PAST SIX HOURS, INITIALLY DEFLECTING SOUTHWARD, TRACKING PARALLEL TO THE NORTH-SOUTH ORIENTED MOUNTAIN RANGE ALONG THE NORTHEAST COAST OF TAIWAN. OVER THE PAST FEW HOURS, THE SYSTEM IS LOOPING CYCLONICALLY BACK TO THE NORTH. TY 05W HAS MAINTAINED A SMALL EYE IN RADAR IMAGERY, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. HOWEVER, ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE RAPID LOSS OF THE WELL-DEFINED EYE FEATURE AND ALSO REVEALS SIGNIFICANT WEAKENING OF THE CORE CONVECTION DUE TO PROLONGED INTERACTION WITH LAND. A 241350Z GMI 89 GHZ MICROWAVE IMAGE REVEALS A MORE ASYMMETRIC CORE SURROUNDING AN OBLONG MICROWAVE EYE FEATURE, WITH THE BULK OF THE DEEP CONVECTIVE BANDING CONFINED TO THE SOUTHERN SEMICIRCLE. SURFACE OBSERVATIONS ARE UNAVAILABLE NEAR THE CENTER AT THIS TIME. ENVIRONMENTAL CONDITIONS HAVE DEGRADED SLIGHTLY WITH INCREASING VERTICAL WIND SHEAR (15-20 KNOTS) OFFSET BY ROBUST RADIAL OUTFLOW AND WARM SST VALUES. THE INITIAL INTENSITY IS ASSESSED AT 110 KNOTS BASED OFF THE SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 102-127 KNOTS AND THE CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) EXTENSION TO THE NORTH AND NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T5.5 - 102 KTS KNES: T5.5 - 102 KTS DEMS: T6.5 - 127 KTS CIMSS ADT: 112 KTS AT 241200Z CIMSS AIDT: 108 KTS AT 241200Z CIMSS DPRINT: 107 KTS AT 241200Z CIMSS DMINT: 116 KTS AT 240931Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: LAND INTERACTION WITH EASTERN TAIWAN ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 05W IS FORECAST TO QUICKLY COMPLETE THE CYCLONIC LOOP AND WILL TRACK GENERALLY WEST-NORTHWESTWARD MAKING LANDFALL WITHIN THE NEXT FEW HOURS. THEN THE SYSTEM WILL ACCELERATE WEST-NORTHWESTWARD AS IT TRACKS ACROSS NORTHERN TAIWAN, WEAKENING RAPIDLY, WITH LIKELY DE-COUPLING OF THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND THE UPPER-LEVEL CIRCULATION CENTER. A LEESIDE JUMP IN THE LLCC POSITION MAY OCCUR AS THE SYSTEM EMERGES OVER THE TAIWAN STRAIT NEAR TAU 12, WHICH IS TYPICAL OF TAIWAN-CROSSING TYPHOONS. AFTER TAU 12, THE SYSTEM IS EXPECTED TO GRADUALLY BECOME VERTICALLY ALIGNED AS IT TRACKS ACROSS THE TAIWAN STRAIT WITH LANDFALL OVER SOUTHEAST CHINA ANTICIPATED NEAR TAU 24. AS TY 05W TRACKS INLAND, IT WILL WEAKEN RAPIDLY AND TURN NORTHWESTWARD TOWARD A BREAK IN THE STR ASSOCIATED WITH A SERIES OF MAJOR SHORTWAVE TROUGHS. DISSIPATION IS EXPECTED BY TAU 72. MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE SOLE OUTLIER, DETERMINISTIC GUIDANCE REMAINS IN FAIR AGREEMENT, WITH INCREASING UNCERTAINTY AFTER TAU 48 DURING THE RECURVE PHASE. THE ECMWF ENSEMBLE (EPS) SUPPORTS THE TRACK PHILOSOPHY, WITH THE LARGE MAJORITY OF SOLUTIONS (GREATER THAN 80 PERCENT) SHOWING A RECURVE TO THE NORTH. THE 240600Z GFS ENSEMBLE (GEFS) IS NOW BIFURCATED, REFLECTING INCREASING UNCERTAINTY IN THE LATER TAUS. RELIABLE INTENSITY GUIDANCE INCLUDING COAMPS-TC (BOTH COTC AND CTCX), HAFS-A AND HWRF SUPPORT THE JTWC INTENSITY FORECAST WITH HIGH CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: HIGH// NNNN