WDPS31 PGTW 072100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23P (FILI) WARNING NR 015// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 24.8S 165.0E INITIAL INTENSITY: 45 KTS GEOGRAPHIC REFERENCE: 173 NM SOUTH-SOUTHWEST OF NOUMEA, NEW CALEDONIA MOVEMENT PAST 6 HOURS: SOUTHWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 19 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TC 23P HAS ENTERED THE TERMINAL PHASE, AND IS RAPIDLY TRANSITIONING TO A SUBTROPICAL STORM. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE EFFECTS OF THE PERSISTENT WESTERLY SHEAR, WITH THE SYSTEM NOW DECAPITATED AND THE CONVECTIVE MASS PUSHED OFF WELL TO THE EAST OF A NOW NAKED LOW LEVEL CIRCULATION CENTER (LLCC). HWRF CROSS SECTIONS REVEAL THE VORTEX EXTENDS ONLY UP TO ABOUT 700MB, WITH A VERY DRY AIR MASS OVERLYING THE LOW LEVEL VORTEX ABOVE ABOUT 850MB. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN ANIMATED SHORTWAVE INFRARED IMAGERY. THE INITIAL INTENSITY OF 45 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, ON THE HIGHER END OF THE AVAILABLE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A LOW TO MID-LEVEL SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T2.5 - 35 KTS PHFO: T3.0 - 45 KTS CIMSS SATCON: 46 KTS AT 071426Z CIMSS ADT: 41 KTS AT 071740Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 25-30 KTS SST: 25-26 CELSIUS OUTFLOW: MODERATE EASTWARD OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT IN THE LOW TO MID-LEVELS. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: TC 23P WILL CONTINUE TO TRACK SOUTHEASTWARD ALONG THE SOUTHWESTERN SIDE OF THE LOW TO MID-LEVEL RIDGE TO THE EAST. THE MID-LEVEL SUBTROPICAL WESTERLIES CONTINUE TO EXERT SIGNIFICANT SHEAR ON THE SYSTEM, AS EXHIBITED BY THE RECENT DECAPITATION. THE SYSTEM WILL SLOWLY WEAKEN AS IT CONTINUES TRACKING SOUTHEASTWARD OVER THE NEXT 24 HOURS, BUT IS FORECAST TO REMAIN AT OR ABOVE GALE-FORCE THROUGH THE FORECAST PERIOD. THE SYSTEM IS ALREADY IN THE PROCESS OF TRANSITIONING TO A SUBTROPICAL LOW AND IS EXPECTED TO FULLY TRANSITION TO A GALE-FORCE SUBTROPICAL STORM NO LATER THAN TAU 24 AS IT BECOMES EMBEDDED WITHIN THE STRONG SUBTROPICAL WESTERLIES, AND MOVES OVER PROGRESSIVELY COOLER WATERS. BEYOND THE FORECAST PERIOD, THE SYSTEM WILL LINGER FOR A COUPLE OF DAYS AS A GALE-FORCE LOW, DRIFTING TO THE EAST AS A STRONG LOW-LEVEL HIGH PRESSURE SYSTEM DEVELOPS TO THE SOUTH. MODEL DISCUSSION: DYNAMIC TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST. AFTER THE FORECAST PERIOD HOWEVER, THE GUIDANCE DIVERGES SIGNIFICANTLY AS THE STORM MOTION BECOMES MORE ERRATIC AS IT WEAKENS AND COMES UNDER THE INFLUENCE OF THE LOW LEVEL STEERING FLOW. INTENSITY GUIDANCE IS MIXED, CONTINUING THE RECENT TREND OF THE GLOBAL MODELS SHOWING RAPID WEAKENING THROUGH TAU 36, WHILE THE MESOSCALE MODELS HOLD ONTO A 40-45 KNOT SYSTEM THROUGH TAU 120. OVERALL CONFIDENCE IN THE JTWC FORECAST IS MEDIUM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN