WDPN31 PGTW 031500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 31W (KALMAEGI) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 10.6N 126.3E INITIAL INTENSITY: 90 KTS GEOGRAPHIC REFERENCE: 392 NM SOUTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 26 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON 31W (KALMAEGI) WITH AN EXTREMELY SYMMETRIC AND VERY COLD CENTRAL DENSE OVERCAST (CDO) DIRECTLY OVER THE CENTER. THE SYSTEM HAS ABOUT AS STRONG OF AN APPEARANCE AS POSSIBLE WITHOUT HAVING AN EYE. AS OF 031200Z, 31W IS ABOUT 70 NM OFF THE COAST OF LEYTE, WITH LANDFALL EXPECTED IN THE NEXT 4-6 HOURS. A 031016Z F16 SSMIS 91 GHZ MICROWAVE IMAGE REVEALED A HIGHLY COMPACT CORE WITH A SMALL MICROWAVE EYE FEATURE AND A DEFINED CONVECTIVE BAND ALONG THE WESTERN PERIPHERY. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EXTRAPOLATION FROM THE SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 90 KTS IS BASED ON ALL AGENCY DVORAK FIXES AGREEING ON T5.O. HOWEVER, THE ASSESSMENT IS MADE WITH LOW CONFIDENCE DUE TO THE SYSTEM LACKING AN EYE, WHICH WOULD GREATLY INCREASE THE CONFIDENCE IN INTENSITY. ENVIRONMENTAL ANALYSIS INDICATES THAT 31W IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD AND EQUATORWARD OUTFLOW ALOFT, MODERATE (15-20 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF AN ELONGATED SUBTROPICAL RIDGE (STR) CENTERED NORTHWEST OF LUZON AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS RJTD: T5.0 - 90 KTS RCTP: T5.0 - 90 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 86 KTS AT 031200Z CIMSS ADT: 74 KTS AT 031200Z CIMSS AIDT: 76 KTS AT 031200Z CIMSS D-MINT: 82 KTS AT 031020Z CIMSS D-PRINT: 80 KTS AT 031230Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD OTHER FACTORS: LAND INTERACTION ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: AFTER MAKING LANDFALL IN LEYTE IN THE COMING HOURS, 31W IS FORECAST TO GRADUALLY TURN MORE NORTHWESTWARD AS IT ROUNDS THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE NORTH. 31W WILL THEN TRACK ACROSS THE VISAYAS AND ENTER THE NORTHERN SULU SEA AROUND TAU 24. THE SYSTEM WILL THEN TRAVERSE ACROSS THE SOUTH CHINA SEA AND MAKE A FINAL LANDFALL IN VIETNAM. THIS FINAL LANDFALL IS FORECAST TO OCCUR JUST AFTER TAU 72 WITHIN CENTRAL VIETNAM. REGARDING INTENSITY, 31W IS FORECAST TO WEAKEN MARGINALLY THROUGH ITS TRACK THROUGH THE VISAYAS DUE TO TERRAIN INTERACTION. THE SYSTEM IS FORECAST TO MAINTAIN TYPHOON INTENSITY THROUGHOUT THIS TIME THOUGH. AFTER EMERGING WITHIN THE SULU SEA, REINTENSIFICATION WILL ENSUE AS STRONG POLEWARD OUTFLOW AND WARM SEA SURFACE TEMPERATURES CREATE A FAVORABLE ENVIRONMENT. ONCE 31W MAKES LANDFALL IN VIETNAM, RUGGED TERRAIN INTERACTION WILL RAPIDLY DETERIORATE THE VORTEX. COMPLETE DISSIPATION IS FORECAST TO OCCUR AROUND TAU 96 AS THE REMNANT VORTEX TRACKS INTO EASTERN THAILAND. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN VERY GOOD AGREEMENT WITH A MERE 85 NM CROSS-TRACK SPREAD AT TAU 72 AND 175 NM CROSS-TRACK SPREAD AT TAU 96. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN A BIT BETTER AGREEMENT WITH MODELS AGREEING ON WEAKENING THROUGH TAU 24 AND INTENSIFICATION THROUGH TAU 60. PEAK INTENSITIES WITHIN THE SOUTH CHINA SEA RANGE FROM 90 KTS (GFS) TO 125 KTS (COAMPS-TC). HAFS-A AND HWRF FALL IN THE MIDDLE, AROUND 95-105 KTS, AND THE JTWC INTENSITY FORECAST FOLLOWS MORE CLOSELY TO THOSE MODELS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN