WDPN31 PGTW 110900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (BEBINCA) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 14.5N 141.9E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 171 NM WEST-NORTHWEST OF NAVSTA GUAM MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 20 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION (LLC) WITH INTENSE DEEP CONVECTIVE BURSTS FLARING ALONG THE EASTERN SEMICIRCLE OF THE LLC DUE TO STRONGLY CONVERGENT LOW-LEVEL FLOW. ANIMATED WATER VAPOR RGB IMAGERY AND TOTAL PRECIPITABLE WATER IMAGERY INDICATE AN EXTENSIVE REGION OF DRY AIR WEST AND NORTHWEST OF THE SYSTEM ASSOCIATED WITH A BROAD UPPER LOW AND SUBSIDENCE. THIS DRY AIR IS ENCROACHING ON THE WESTERN SEMICIRCLE OF THE SYSTEM, HINDERING CONVECTIVE DEVELOPMENT. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MSI, AND AN 110412Z AMSR2 WINDSPEED IMAGE WHICH SHOWS AN ELONGATED CENTER ADJACENT TO A SWATH OF STRONG WINDS. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW AND KNES SUBJECTIVE DVORAK ESTIMATES. CIMSS OBJECTIVE INTENSITY ESTIMATES RANGE FROM 38 TO 57 KNOTS. THE PREVIOUS INTENSITY AT 110000Z HAS BEEN REANALYZED FROM 30 TO 35 KNOTS BASED ON AN 110012Z ASCAT-B WINDSPEED IMAGE SHOWING MAXIMUM WINDS OF 33 KNOTS. INITIAL WIND RADII BASIS: OTHER CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T3.0 - 45 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 40 KTS AT 110330Z CIMSS ADT: 57 KTS AT 110600Z CIMSS AIDT: 46 KTS AT 110600Z CIMSS DPRINT: 39 KTS AT 110600Z CIMSS DMINT: 38 KTS AT 110414Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 10-15 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE RADIAL OTHER FACTORS: DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE PEAK INTENSITY HAS BEEN INCREASED MODESTLY IN THE EXTENDED FORECAST PERIOD. FORECAST DISCUSSION: TROPICAL STORM (TS) 14W IS FORECAST TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 36 ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED STR. THE SYSTEM IS EXPECTED TO INTENSIFY AT A SLOWER- THAN-CLIMATOLOGICAL RATE, PRIMARILY DUE TO THE PRESENCE OF DRY AIR OVER THE WESTERN SEMICIRCLE. TS 14W WILL CONSOLIDATE QUICKLY AFTER TAU 36 AS THE SYSTEM BECOMES MORE VERTICALLY ALIGNED, DEVELOPS CENTRALIZED CONVECTION, AND RE-MOISTENS. AFTER TAU 36, THE SYSTEM WILL TRACK GENERALLY WEST-NORTHWESTWARD AS IT TRANSITIONS TOWARD THE STEERING INFLUENCE OF A STRONG STR POSITIONED OVER THE EAST CHINA SEA AND JAPAN. ENVIRONMENTAL CONDITIONS WILL FAVOR RAPID INTENSIFICATION (RI), THEREFORE, TS 14W WILL INCREASE INTENSITY FROM 65 KNOTS AT TAU 48 TO 95 KNOTS AT TAU 72, WITH FURTHER INTENSIFICATION TO 115 KNOTS BY TAU 96 AS THE SYSTEM TRACKS PAST OKINAWA. TS 14W SHOULD MAKE LANDFALL NEAR SHANGHAI, CHINA NEAR TAU 120 WHILE WEAKENING SLIGHTLY DUE TO LAND INTERACTION. MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE REMAINS IN FAIR AGREEMENT THROUGH TAU 72, WITH A 122NM CROSS-TRACK SPREAD AT TAU 72. AFTER TAU 72, THERE IS INCREASING UNCERTAINTY IN THE JTWC TRACK FORECAST WITH A 210NM TO 410NM CROSS-TRACK SPREAD IN GUIDANCE FROM TAU 96 TO TAU 120. BOTH THE HAFS-A AND GFS MODELS HAVE BACKED OFF ON DRY AIR ENTRAINMENT SHOWING A MOIST CORE COCOONED FROM THE SURROUNDING DRY AIR. RELIABLE INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH COAMPS- TC (GFS AND NAVGEM) CONTINUING TO PEAK THE INTENSITY AT SUPER TYPHOON STRENGTH AT TAU 96 WHILE HAFS-A PEAKS THE INTENSITY AT 110 KNOTS AT TAU 72. THE 110000Z COAMPS-TC ENSEMBLE INTENSITY CHANGE PROBABILITY PRODUCT INDICATES A 60-80 PERCENT RI PROBABILITY FROM TAU 54 TO TAU 96, WHICH SUPPORTS THE JTWC INTENSITY FORECAST PHILOSOPHY. THE JTWC PEAK INTENSITY FORECAST IS HEDGED BETWEEN THE MESOSCALE MODEL FORECASTS WITH A PEAK OF 115 KNOTS. HOWEVER, CONSIDERABLE UNCERTAINTY IN THE PEAK INTENSITY REMAINS IN THE EXTENDED PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN