WDPN31 PGTW 072100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (MUN) WARNING NR 025// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 38.0N 148.3E INITIAL INTENSITY: 25 KTS GEOGRAPHIC REFERENCE: 360 NM EAST-SOUTHEAST OF MISAWA, JAPAN MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS NOTHING BUT FIELDS OF STRATOCUMULUS LEFT WITH THIS SYSTEM AS IT ROLLS INTO THE HIGHER LATITUDES. THE LOW LEVEL VORTEX IS EXPOSED AND CLEARLY VISIBLE IN ALL TYPES OF IMAGERY YET STILL MAINTAINS A TIGHT WRAP. DURING THE PAST 12 HOURS THE SYSTEM ROUNDED THE WESTERN FLANK OF THE SUBTROPICAL RIDGE AND IS NOW RUNNING TOWARDS A MERGE INTO THE BAROCLINIC ZONE. HOWEVER, THE DISPLACEMENT BETWEEN THE SYSTEM AND THE POLAR FRONT JET (PFJ) REMAINS FAR ENOUGH AND THE ANGLE OF APPROACH LOW ENOUGH THAT THE SYSTEM IS IN AN ENVIRONMENT WHERE IT WILL SURVIVE AND DECAY ONLY VERY SLOWLY OVER THE NEAR TERM AS IT COOLS FROM BELOW. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: THE NORTHWESTERN FLANK OF THE SUBTROPICAL RIDGE. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T2.0 - 30 KTS RCTP: T2.0 - 30 KTS CIMSS ADT: 25 KTS AT 071420Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 30+ KTS SST: 19-20 CELSIUS OUTFLOW: WEAK POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE SYSTEM WILL NOT COMPLETE SUBTROPICAL TRANSITION BUT WILL RATHER UNDERGO EXTRA-TROPICAL TRANSITION. FORECAST DISCUSSION: THE PFJ IS WELL NORTH OF HOKKAIDO SO IT WILL BE A LONG SLOW MERGE INTO THE BAROCLINIC ZONE FOR TROPICAL DEPRESSION HUN. AS IT GRADUALLY FADES POLEWARD, VERTICAL WINDSHEAR WILL INCREASE FROM ABOVE AND COOLING WATERS WILL WEAKEN IT FROM BELOW AND THE SYSTEM WILL BE UNFINDABLE SOMEWHERE NEAR THE 45TH LATITUDE. THE LATEST SATELLITE FIX FROM JTWC AT THE TIME OF THIS BULLETIN WAS POSITION ONLY WITH THE DVORAK CLASSIFIED AS TOO WEAK. DISSIPATION IS JUST A MATTER OF TIME. MODEL DISCUSSION: MODELS ARE IN EXCELLENT AGREEMENT ON BOTH TRACK AND INTENSITY TRENDS. NO VORTEX TRACKERS CARRY THE SYSTEM BEYOND TAU 36 WITH EXCEPTION OF THE HAFS-A MODEL. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN