WDPN31 PGTW 050900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (PENHA) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 8.2N 127.9E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 310 NM NORTHWEST OF SONSOROL MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 17 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL STORM (TS) 02W (PENHA) AS A SLOWLY CONSOLIDATING SYSTEM WITH LOW-LEVEL FRAGMENTED CLOUD LINES WRAPPING BENEATH THE FLARING CONVECTION IN CLOSE PROXIMITY TO THE OBSCURED SURFACE CENTER. MUCH OF THE SUPPORTIVE CONVECTIVE STRUCTURES REMAIN SHEARED INTO THE NORTHWEST QUADRANT, WHILE THE EASTERN AND SOUTHERN SEMICIRCLES REMAIN LARGELY CONVECTION FREE. VERTICAL ALIGNMENT THROUGH TS 02W HAS CONTINUED TO IMPROVE OVER THE LAST FEW HOURS AS THE SYSTEMS CORE HAS REMAINED COCOONED FROM A LARGE SWATH OF DRY AIR IMMEDIATELY TO THE WEST. THE ENVIRONMENT HAS ALSO REMAINED MARGINALLY FAVORABLE SINCE THE PREVIOUS WARNING, WITH WARM SEA SURFACE TEMPERATURES OF 28-29 C, MODERATE POLEWARD OUTFLOW ALOFT, AND MODERATE TO UNFAVORABLE VWS. THE INITIAL POSITION HAS BEEN PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED MSI IMAGERY. THE INITIAL INTENSITY HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE BASED ON SUBJECTIVE AGENCY DVORAK ESTIMATES AND CIMSS OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTH, EXTENDING WESTWARD OVER LUZON AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.0 - 30 KTS RCTP: T2.5 - 35 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 39 KTS AT 050440Z CIMSS ADT: 35 KTS AT 050530Z CIMSS AIDT: 33 KTS AT 050530Z CIMSS D-MINT: 30 KTS AT 050440Z CIMSS D-PRINT: 33 KTS AT 050610Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 02W IS FORECASTED TO TRACK WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF THE RETREATING STR CENTERED DIRECTLY TO THE NORTH OVER THE NEXT 24 HOURS. FOLLOWING TAU 24, THE TRACK WILL BECOME NORTHWESTWARD AS THE WESTERN EXTENT OF THE RIDGE AXIS CONTINUES TO RETREAT EASTWARD. WHILE THIS OCCURS, THE TRACK BETWEEN TAU 24 AND TAU 48 WILL BECOME NORTHWESTWARD UNTIL COMPLETE DISSIPATION OVER WATER WITHIN THE WESTERN SULU SEA AS TS 02W TRACKS ALONG THE WESTERN-MOST PERIPHERY OF THE STR NOW CENTERED TO THE EAST. REGARDING INTENSITY, TS PENHA IS FORECASTED TO MAINTAIN 40 KTS INTO LANDFALL BETWEEN TAU 6 AND TAU 8 ALONG THE EAST COAST OF MINDANAO, PHILIPPINES. FOLLOWING LANDFALL, TS 02W WILL BEGIN THE INITIAL WEAKENING PHASE AS VWS INCREASES TO NEAR 30 KTS AND TOPOGRAPHICAL FRICTION START TO ERODE THE SYSTEMS CENTRAL VORTEX. AS THE SYSTEM TRACKS OVER MINDANAO AND INTO THE EASTERN SULU SEA, SURFACE INTENSITIES WILL CONTINUE TO GRADUALLY DECREASE TO 30 KTS BY TAU 36 DUE TO PERSISTENT VWS BETWEEN 20-30 KTS AND THE INTRODUCTION OF AN EXPECTED NORTHEASTERLY COLD SURGE EVENT EXTENDING THROUGH THE WEST PHILIPPINE SEA AND WESTERN SULU SEA. BETWEEN TAU 36 AND TAU 48, SURFACE INTENSITIES ARE FORECASTED TO CONTINUE WEAKENING TO NEAR 30 KTS DUE TO MODERATE VWS, SIGNIFICANT DRY AIR ENTRAINMENT, AND PERSISTENT INTERACTION WITH NORTHEASTERLY GRADIENT WINDS. BY TAU 48, TS 02W IS FORECASTED TO LOSE ALL TROPICAL CHARACTERISTICS AND BECOME VERY SHALLOW AS THE CYCLONE BECOMES COMPLETELY EMBEDDED WITHIN THE AFOREMENTIONED EASTERN BOUNDARY OF THE COLD SURGE NEAR PALAWAN. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AND ARTIFICIAL INTELLIGENCE (AI) WEATHER MODELS CONTINUE TO REMAIN IN TIGHT AGREEMENT THROUGH THE INITIAL 36 HOURS OF THE FORECAST PERIOD, CHARACTERIZED BY A CROSS-TRACK SPREAD OF JUST 45 NM. FOLLOWING TAU 36, NUMERICAL MODEL GUIDANCE BEGINS TO DIVERGE DUE TO UNCERTAINTIES WITH THE FORECASTED DISSIPATION PHASE OVER THE SULU SEA ASSOCIATED WITH THE COLD SURGE EVENT MENTIONED ABOVE. ALTHOUGH NAVGEM ILLUSTRATES A NORTHWARD TRACK AFTER TAU 36, ALL OTHER JTWC TRACK CONSENSUS MEMBERS TRACK TS 02W NORTHWESTWARD OVER NORTHERN PALAWAN. THE JTWC TRACK FORECAST HAS BEEN PLACED WITH HIGH CONFIDENCE AND NEAR THE JTWC CONSENSUS SOLUTION THROUGH THE ENTIRETY OF THE FORECAST PERIOD. REGARDING INTENSITY, THE MAJORITY OF JTWC INTENSITY CONSENSUS SOLUTIONS SHOW A WEAKENING PHASE INTO LANDFALL BY TAU 6, WITH THE EXCEPTION OF COAMPS-TC AND HAFS-A, WHICH SHOW SUSTAINED SURFACE INTENSITIES NEAR 40 KTS INTO LANDFALL. ALL JTWC INTENSITY CONSENSUS MEMBERS ILLUSTRATE A WEAKENING TREND THEREAFTER THROUGH LANDFALL AND INTO THE SULU SEA DURING NORTHEASTERLY COLD SURGE INTERACTION. THE JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE THROUGHOUT THE 72 HOURS FORECAST DUE TO UNCERTAINTIES WITH THE INITIAL WEAKENING PHASE DURING LANDFALL AND DURING THE EXPECTED INTERACTION WITH THE NORTHEASTERLY SURGE EVENT. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: MEDIUM// NNNN