WDPN32 PGTW 290900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (SAOLA) WARNING NR 023// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 18.9N 123.1E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 285 NM NORTH-NORTHEAST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 36 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TYPHOON (TY) 09W (SAOLA) HAS UNDERGONE A RATHER REMARKABLE EVOLUTION OVER THE PAST SIX HOURS. AT 290000Z THE SYSTEM SHOWED NOW CLEAR EYE IN VISIBLE OR INFRARED SATELLITE IMAGERY, THOUGH LOW-RESOLUTION AMSU-B MICROWAVE IMAGERY WAS BEGINNING TO HINT THAT A PINHOLE EYE WAS FORMING. SIX HOURS LATER, ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 12NM WIDE EYE WITH EYE TEMPERATURES APPROACHING, BUT NOT YET REACHING, POSITIVE TERRITORY. A 290515Z ATMS 183GHZ IMAGE SHOWED A WELL-DEFINED MICROWAVE EYE WITH A CLOSED EYEWALL. CIMSS M-PERC HOVMULLER DIAGRAMS SHOW A CLASSIC EYEWALL REPLACEMENT CYCLE (EWRC) DEPICTION, WITH THE SECONDARY EYEWALL GRADUALLY CONTRACTING OVER THE PAST 24 HOURS. THE RAPID CLEARING OUT OF THE NEW EYE INDICATES THE EWRC IS NOW COMPLETE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 12NM EYE MENTIONED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE AND IS A BIT AGGRESSIVE, BUT STILL IN LINE WITH THE PGTW AND RCTP DVORAK CURRENT INTENSITY ESTIMATES AND THE RAW ADT OF T6.3. THE SYSTEM IS NO TRACKING TOWARDS THE NORTHWEST ALONG THE SOUTHWEST SIDE OF THE STEERING RIDGE. ANALYSIS SHOWS A FAVORABLE ENVIRONMENT WITH VERY WARM (29-30C) SSTS, MODERATE OCEANIC HEAT CONTENT AND STRONG RADIAL OUTFLOW TEMPERED SLIGHTLY BY THE CONTINUED PROXIMITY TO NORTHEASTERN LUZON AND MODERATE EASTERLY WIND SHEAR. INITIAL WIND RADII BASIS: PERSISTENCE WITH EARLIER SAR DATA. CURRENT STEERING MECHANISM: SOUTHWEST PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T5.5 - 102 KTS RCTP: T6.0 - 115 KTS KNES: T5.5 - 102 KTS CIMSS SATCON: 96 KTS AT 290147Z CIMSS ADT: 107 KTS AT 290530Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: PROXIMITY TO NORTHEAST LUZON. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: HAVING COMPLETED AN EWRC AND THEN RAPID INTENSIFIED, TY 09W IS NOW ON A TRAJECTORY TOWARDS THE NORTHWEST ALONG THE SOUTHWEST SIDE OF A DEEP STR CENTERED EAST OF JAPAN. OVER THE NEXT 24 HOURS, THE SYSTEM WILL PASS THROUGH THE LUZON STRAIT AND ENTER THE NORTHERN PORTION OF THE SOUTH CHINA SEA. DUE TO CONTINUED PRESENCE OF MID-LEVEL (BELOW THE OUTFLOW) LEVEL EASTERLY SHEAR AND POSSIBLE ENTRAINMENT OF DRY AIR INTO THE EASTERN PORTION OF THE CORE, THE SYSTEM IS EXPECTED TO MAINTAIN ITS CURRENT INTENSITY OR WEAKEN SLIGHTLY THROUGH TAU 24. ONCE IN THE SOUTH CHINA SEA, THE SYSTEM IS FORECAST TO CONTINUE TRACKING WEST-NORTHWEST BEFORE THROUGH ABOUT TAU 72. BY TAU 72, A DEEP MID-LATITUDE TROUGH IS FORECAST TO PASS BY TO THE NORTH, BUT IN ITS WAKE A MID TO UPPER-LEVEL ANTICYCLONE IS FORECAST TO DEVELOP WEST OF SHANGHAI. DEVELOPMENT OF THIS RIDGE WILL PUSH TY 09W ONTO A WESTWARD TRACK AFTER TAU 72, TURNING WEST-SOUTHWEST BY THE END OF THE FORECAST AS THE RIDGE EXITS TO THE EAST AND MERGES INTO THE LARGE STR FAR TO THE NORTHEAST. AS THE SYSTEM ENTERS THE SOUTH CHINA SEA, MID-LEVEL SHEAR IS FORECAST TO WEAKEN, SSTS WARM UP TO NEAR 31C AND THE SYSTEM STARTS TO TAP INTO THE POLEWARD OUTFLOW ASSOCIATED WITH THE APPROACHING UPPER-LEVEL TROUGH. THESE CONDITIONS WILL FEED ANOTHER PERIOD OF INTENSIFICATION, UP TO AT LEAST 125 KNOTS BY TAU 48. THEREAFTER, MID-LEVEL SHEAR WILL INCREASE AGAIN AND THE SYSTEM BEGINS TO INGEST DRY CONTINENTAL STREAMING SOUTH OFF THE CHINESE MAINLAND, DISRUPTING THE INNER CORE OF THE SYSTEM, LEADING TO STEADY WEAKENING THROUGH THE REMAINDER OF THE FORECAST. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE HAVE WITH THIS RUN BEGUN TO DIVERGE SIGNIFICANTLY. THE LATEST CONSENSUS PACKAGE IS IN FAIRLY GOOD AGREEMENT THROUGH THE FIRST 48 HOURS, THOUGH THE GFS AND ECMWF BEGIN TO DIVERGE AT THIS POINT. GFS IS BY THIS POINT THE SOUTHERN OUTLIER WHILE ECMWF IS THE NORTHERN OUTLIER. BY TAU 72, THE BIFURCATION BETWEEN THE OUTLIERS INCREASES SHARPLY, WITH THE GFS LYING SOUTH OF HONG KONG WHILE THE ECMWF IS NEARING LANDFALL NORTH OF SHANTAU, CHINA. THE BY TAU 120, THE GFS LIES JUST NORTH OF HAINAN ISLAND WHILE THE ECMWF IS INLAND WEST OF SHANTAU, LEADING TO A 400NM SPREAD BY THE END OF THE FORECAST. THE ENSEMBLE GUIDANCE IS IN SIMILAR DISARRAY, BOTH BETWEEN THE ENSEMBLE MODELS AND WITHIN THEM. THE GEFS ENSEMBLE NOW SHOWS ROUGHLY HALF OF THE MEMBERS TAKING THE ECMWF TRACK, WHILE THE ECENS INDICATES ABOUT A THIRD OF THE MEMBERS TAKING THE GFS TRACK. THE JTWC FORECAST IS CONSISTENT WITH THE CONSENSUS MEAN THROUGH THE FORECAST PERIOD. HOWEVER, WITH THE LARGE AND INCREASING SPREAD IN THE DETERMINISTIC AND ENSEMBLE MEMBERS, THERE IS MEDIUM CONFIDENCE IN THE EARLY PORTION OF THE FORECAST, BUT LOW CONFIDENCE IN THE LATER HALF OF THE FORECAST PERIOD. INTENSITY GUIDANCE IS STRUGGLING DUE TO THE UNEXPECTED RAPID INTENSIFICATION WITNESSED OVER THE PAST SIX HOURS. HOWEVER, THE HAFS-A AND COAMPS-TC (GFS) APPEAR TO BE HANDLING IT THE BEST AND THE JTWC FORECAST CLOSELY TRACKS THESE TRACKERS THROUGH THE FORECAST PERIOD. ADDITIONALLY, THE COAMPS-TC ENSEMBLE INTENSITY PROBABILITIES INDICATE A HIGH PROBABILITY (95 PERCENT) OF RI BETWEEN TAU 48 TO TAU 60, LENDING HIGHER CONFIDENCE TO THE JTWC FORECAST. HOWEVER, CONFIDENCE IS DECREASED DUE TO THE HIGH UNCERTAINTY IN THE LONG-RANGE TRACK AND OBVIOUSLY AN EARLIER TRACK INLAND WOULD NEGATE THE CURRENT INTENSITY FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN