WDPN32 PGTW 122100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05E (DORA) WARNING NR 050// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.6N 176.4E INITIAL INTENSITY: 65 KTS GEOGRAPHIC REFERENCE: 810 NM WEST OF JOHNSTON ISLAND MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 27 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN INCREASINGLY SHEARED SYSTEM, WITH UPPER-LEVEL CIRRUS STREAMING TOWARDS THE LOW-LEVEL CIRCULATION CENTER (LLCC) OUT OF THE SOUTHWEST. THE LLCC APPEARS TO BE LOCATED NEAR THE SOUTHWESTERN EDGE OF THE DEEP CONVECTIVE MASS. IN THE ABSENCE OF RELIABLE OBJECTIVE SATELLITE DATA, THE INITIAL INTENSITY IS LOWERED TO 65 KT IN AGREEMENT WITH AGENCY DVORAK ESTIMATES. A POLEWARD OUTFLOW CHANNEL REMAINS ESTABLISHED INTO THE EASTERN FLANK OF AN UPPER-LEVEL TROUGH TO THE NORTHWEST WHICH IS IN THE PROCESS OF PINCHING OFF INTO A CUTOFF LOW. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS CIMSS ADT: 94 KTS AT 121730Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 20-25 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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: DORA CONTINUES TO DECAY AS MODERATE SOUTHWESTERLY VERTICAL SHEAR ERODES ITS INNER CORE. GRADUAL TO STEADY WEAKENING IS LIKELY TO CONTINUE THROUGH AT LEAST THE NEXT 48 HOURS AS SHEAR HOLDS AT THIS MAGNITUDE DUE TO THE UPPER-LEVEL TROUGH TO THE NORTHWEST. AS DORA TURNS NORTHWARD TO THE EAST OF THIS TROUGH, THE TROUGH WILL PINCH OFF INTO A CUTOFF UPPER LOW AND WEAKEN. AS THIS OCCURS, DORA MAY ENCOUNTER LOWER SHEAR DURING AT LEAST A PORTION OF THE 72-120 HOUR PERIOD. ADDITIONALLY, THERE IS A DEEP LAYER OF MOISTURE ON THE SOUTHEASTERN FLANK OF THE UPPER LOW THAT MAY END UP POSITIONED ON THE UPSHEAR (SOUTHWEST) SIDE OF DORA DURING THIS TIME, REDUCING THE AMOUNT OF DRY VENTILATION OF THE VORTEX. THESE FACTORS COULD LEAD TO A REINTENSIFICATION OF DORA IN THE LATTER PORTION OF THE FORECAST, A SCENARIO THAT IS NOW ESPOUSED BY THE GFS, HAFS-A, HWRF, AND COAMPS-TC. HOWEVER, THERE REMAINS A POSSIBILITY THAT DORA SIMPLY DISSIPATES PRIOR TO THIS WINDOW OF OPPORTUNITY, ESPECIALLY IF IT TRACKS CLOSER TO THE UPPER-LEVEL LOW. THE JTWC FORECAST SHOWS REINTENSIFICATION TO 50 KT AT 120 HOURS AFTER WEAKENING TO A MINIMUM OF 45 KT DURING THE 72-96 HOUR TIMEFRAME. ALONG-TRACK SPREAD EXPLODES TO LARGE VALUES AT 96-120 HOURS DUE TO UNCERTAINTY IN HOW QUICKLY DORA WILL REACH A FRONTAL BOUNDARY TO THE NORTH AND GET USHERED NORTHEASTWARD ALONG THAT BOUNDARY. TRACK FORECAST CONFIDENCE IS LOWER THAN AVERAGE DURING THIS PERIOD. THE SAME FRONTAL BOUNDARY WILL ALSO INDUCE EXTRATROPICAL TRANSITION BY 120 HOURS OR SO, BUT THIS TIMING COULD CHANGE BASED ON THE AFOREMENTIONED UNCERTAINTY IN THE TIMING OF THE FRONTAL INTERACTION. MODEL DISCUSSION: THE JTWC TRACK FORECAST IS SLIGHTLY TO THE RIGHT OF THE MULTI-MODEL CONSENSUS DUE TO THE WEAK REPRESENTATION OF DORA IN SOME MEMBERS OF THE CONSENSUS, SUCH AS ECMWF, WHICH SHOW A SHALLOW VORTEX THAT IS STEERED MORE WESTWARD, LIKELY UNREALISTICALLY SO. THE JTWC INTENSITY FORECAST IS CLOSE TO THE MEAN OF HAFS-A, HWRF, COAMPS-TC, AND GFS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN