WDPN32 PGTW 062100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (DANAS) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 23.8N 120.5E INITIAL INTENSITY: 70 KTS GEOGRAPHIC REFERENCE: 95 NM SOUTHWEST OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: OVER LAND SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON 05W (DANAS) WITH A SIGNIFICANTLY WEAKENED APPEARANCE SINCE MAKING LANDFALL WITHIN SOUTHWESTERN TAIWAN AT AROUND 1500Z. THE DEFINED EYE HAS NOW FILLED AND THE MOUNTAINOUS TERRAIN OF CENTRAL TAIWAN IS RAPIDLY WEAKENING THE VORTEX. ENVIRONMENTAL ANALYSIS INDICATES THAT 05W IS IN AN UNFAVORABLE ENVIRONMENT DUE PRIMARILY TO THE SYSTEM BEING OVER LAND. OTHER ENVIRONMENTAL FACTORS ARE RELATIVELY FAVORABLE WITH MODERATE EQUATORWARD OUTFLOW ALOFT AND LOW (10-15 KTS) VERTICAL WIND SHEAR. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON ANIMATED EIR AND RADAR IMAGERY. THE INITIAL INTENSITY OF 70 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON A WEAKENING TREND OVER LAND. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A NEAR-EQUATORIAL RIDGE CENTERED TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: NO CURRENT ESTIMATE RJTD: T4.5 - 77 KTS CIMSS SATCON: 70 KTS AT 061600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 10-15 KTS SST: OVER LAND OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: RUGGED TERRAIN INTERACTION ANALYSIS CONFIDENCE: INITIAL POSITION: LOW INITIAL INTENSITY: LOW INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: 05W IS FORECAST TO CONTINUE TRACKING NORTHEASTWARD, ALONG THE NORTHWESTERN PERIPHERY OF THE NEAR-EQUATORIAL RIDGE THROUGH TAU 24. A JUMP IN THE TRACK IS POSSIBLE OVER THE NEXT 6 HOURS AS THE LOW-LEVEL CENTER QUICKLY TRAVERSES ACROSS WESTERN AND NORTHERN TAIWAN. NEAR TAU 24, RIDGING WILL EXTEND OVER TO THE NORTH OF THE VORTEX, WHICH WILL TURN THE SYSTEM SHARPLY WESTWARD TOWARDS MAINLAND CHINA. A WESTWARD TO SOUTHWESTWARD TRACK WILL THEN CONTINUE THROUGH THE REMAINDER OF THE FORECAST PERIOD AS THE REMNANT VORTEX TRACKS FURTHER INLAND. REGARDING INTENSITY, 05W IS FORECAST TO CONTINUE FEELING THE EFFECTS OF TERRAIN INTERACTION THROUGH TAU 12, CAUSING FURTHER WEAKENING. ONCE THE SYSTEM EMERGES TO THE NORTH OF TAIWAN, OUTFLOW WILL ALMOST ENTIRELY CEASE AND NORTHEASTERLY SHEAR WILL BEGIN TO INCREASE. THIS WILL CREATE A MARGINAL ENVIRONMENT, AND 05W IS EXPECTED TO CONTINUE WEAKENING AS IT APPROACHES THE EASTERN COAST OF CHINA. A SECOND LANDFALL IS CURRENTLY FORECAST TO OCCUR JUST AFTER TAU 36. AFTER THE SECOND LANDFALL, 05W IS EXPECTED TO RAPIDLY DETERIORATE OVER LAND WITH DISSIPATION NEAR TAU 72. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 36 WITH AN 80 NM CROSS-TRACK SPREAD AT TAU 36. AFTER TAU 36, BOTH CROSS-TRACK AND ALONG-TRACK SPREAD INCREASE AS THE WEAKENED VORTEX TRACKS OVER LAND. THE MAIN OUTLIER IS GFS, WHICH HAS THE SYSTEM TAKE A WIDER TURN AT TAU 24 AND THEN A MUCH SHARPER SOUTH-SOUTHWESTWARD TURN, NEARLY BACK INTO THE TAIWAN STRAIT, AFTER TAU 36. THE JTWC TRACK FORECAST FOLLOWS MORE CLOSELY TO THE MAIN GROUPING OF GUIDANCE WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON WEAKENING THROUGHOUT THE FORECAST PERIOD WITH ALL MODELS (EXCEPT FOR GFS) SUGGESTING DISSIPATION BY TAU 72. AS A RESULT, THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS THROUGHOUT THE FORECAST PERIOD. THERE IS SOME UNCERTAINTY REGARDING HOW WEAK THE SYSTEM WILL BE AFTER IT PASSES OVER WATER, SO THE INTENSITY FORECAST IS PLACED WITH ONLY MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN