WDPN32 PGTW 060900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (KUJIRA) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.0N 121.7E INITIAL INTENSITY: 25 KTS GEOGRAPHIC REFERENCE: 150 NM NORTH-NORTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 10 KTS SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL DEPRESSION 13W (KUJIRA) AS A POORLY CONSOLIDATED SYSTEM THAT APPEARS TO BE MOSTLY, IF NOT ALL, CONFINED TO THE MIDLEVEL AT THIS POINT. STRONG GRADIENT FLOW FROM THE WEST AND NORTHWEST DOMINATE ANIMATED MSI; THE FLOW SURGES OVER LUZON AND CONVERGES ON THE EASTERN COAST, CAUSING THE LINE OF DEEP CONVECTION. THE 060430Z OSCAT DATA CONFIRMS WHAT IS IDENTIFIABLE IN ANIMATED IMAGERY: STRONG STRAIGHT-LINE FLOW PRESENT ON BOTH SIDES OF LUZON. ADDITIONALLY, SURFACE OBSERVATIONS FROM LUZON DO NOT SUPPORT THE PRESENCE OF A SURFACE CIRCULATION, WITH APARRI REPORTING NORTHWESTERLIES AT 12 KTS AND TUGUEGARAO (APPROXIMATELY 35 NM FROM THE ASSESSED CENTER) REPORTING 2 KT EAST-NORTHEASTERLIES. THE PERSISTENT MIDLEVEL TURNING IS BEGINNING TO BE SHEARED APART AND BECOMING SIGNIFICANTLY LESS DEFINED AS IT TRACKS ACROSS LUZON AND EMERGES OVER WATER. IT IS DIFFICULT TO DETERMINE IF THE LOW LEVEL CENTER IS TRULY GONE WHILE THE SYSTEM REMAINS OVER LUZON, THOUGH THE OSCAT AND SURFACE OBSERVATIONS ARE STRONG INDICATORS. ENVIRONMENTAL ANALYSIS REVEALS A HIGHLY UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY MOUNTAINOUS TERRAIN INTERACTION OVER LUZON, MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR (VWS), AND STRONG WESTERLY GRADIENT FLOW ENHANCED BY INFLOW TO TYPHOON 12W (DOLPHIN). THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON THE PGTW POSITION FIX AND MIDLEVEL ROTATION. THE INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON A WEAKENING TREND OVER LAND AND THE WEAK SURFACE OBSERVATIONS. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: EXTENSIVE LOWER-LEVEL WESTERLY MONSOONAL SURGE FLOW AGENCY DVORAK AND AUTOMATED FIXES: PGTW: NO CURRENT ESTIMATE KNES: T1.5 - 25 KTS CIMSS D-MINT: 30 KTS AT 060521Z CIMSS D-PRINT: 28 KTS AT 060610Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE VWS: 20-25 KTS SST: OVER LAND OUTFLOW: WEAK EQUATORWARD OTHER FACTORS: TERRAIN INTERACTION WHILE POSITIONED OVER LUZON ANALYSIS CONFIDENCE: INITIAL POSITION: LOW INITIAL INTENSITY: LOW INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 13W (KUJIRA) WILL CONTINUE TRACKING OVER LUZON WHILE REMAINING UNDER THE STEERING INFLUENCE OF THE WESTERLY SURGE, EMERGING OVER WATER WITHIN THE NEXT FEW HOURS. ONCE OVER WATER, THE SHALLOW REMNANTS OF 13W WILL BE CARRIED NORTHEASTWARD AS IT GETS ABSORBED INTO TY 12W'S INFLOW. 13W IS EXPECTED TO BE FULLY DISSIPATED NO LATER THAN TAU 24; HOWEVER, THE SURFACE CIRCULATION HIGHLY LIKELY DISSIPATED OVER LUZON AND THE REMNANT MIDLEVEL CIRCULATION WILL LIKELY BE GONE WITHIN 12 HOURS. WIND SPEEDS ARE EXPECTED TO REMAIN ELEVATED THROUGHOUT THE FORECAST PERIOD DUE TO THE ACCELERATED WESTERLIES. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 24, SUPPORTING THE JTWC TRACK FORECAST WITH HIGH CONFIDENCE. DETERMINISTIC GFS AND ECMWF DEPICT 13W REEMERGING OVER THE PHILIPPINE SEA AS AN OPEN TROUGH RATHER THAN A CLOSED CIRCULATION, SUPPORTING DISSIPATION PRIOR TO TAU 24. RELIABLE INTENSITY AIDS ARE IN STRONG AGREEMENT THAT 13W WILL NOT INTENSIFY WHEN REEMERGING OVER WATER, AND DEPICT THE STRONG WESTERLIES DRIVING THE INCREASED WIND SPEEDS VICE THE CIRCULATION ITSELF. AS A RESULT, THE JTWC INTENSITY FORECAST IS ASSESSED WITH HIGH CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: HIGH// NNNN