WDPN31 PGTW 170300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.5N 133.5E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 477 NM SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 15 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CONTINUING CONSOLIDATION AROUND THE LOW LEVEL CIRCULATION CENTER (LLCC). DEEP CONVECTION IS CONCENTRATED OVER THE EASTERN SEMICIRCLE AND TOTAL PRECIPITABLE WATER LOOPS VERIFY THE EXISTANCE OF MUCH DRIER AIR OVER THE NORTHWESTERN SEMICIRCLE. THE DRIER AIR AND INCREASING UPPER LEVEL CONVERGENCE ASSOCIATED WITH THE UPPER LEVEL TROUGH IS SLOWING THE DEVELOPMENT OF THE SYSTEM AND CREATING A MORE SUBSIDENT ENVIRONMENT UPSTREAM ALONG TRACK. PRESSURE FALLS DURING THE PAST 12 HOURS IN THE CORE OF THE SYSTEM AND DECREASING RADII OF THE OUTERMOST CLOSED ISOBAR VERIFY STEADY DEEPENING AND CONSOLIDATION OF THE SYSTEM. THE INITIAL POSITION IS FIXED WITH MODERATE CONFIDENCE BASED ON THE PGTW FIX ON A PARTIALLY EXPOSED LLLCC IN ANIMATED MULTISPECTRAL IMAGERY. THE INITIAL INTENSITY ASSESSMENT IS BASED ON A 162335Z PARTIAL ASCAT PASS, PRESSURE TRENDS, AND A BLEND BETWEEN THE PGTW AND ADT DVORAK ASSESSMENTS. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: TD 09W IS STEERING IN A COMPLEX MONSOON GYRE PATTERN. CURRENTLY IT IS BEING NUDGED NORTHWESTWARD BY THE WESTERN PERIPHERY OF THE NEAR EQUATORIAL RIDGE, BUT AS IT TRACKS FURTHER POLEWARD THE SUBTROPICAL RIDGE WILL FORCE IT ON A MORE WESTWARD TRACK. THE HAND-OFF BETWEEN STEERING FORCES WILL OCCUR BETWEEN THE 24TH AND 26TH LATITUDES. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.0 - 25 KTS RJTD: T1.5 - 25 KTS KNES: T2.5 - 35 KTS CIMSS ADT: 37 KTS AT 162340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD OTHER FACTORS: AFTER TAU 24, OCEAN HEAT CONTENT ALONG TRACK WILL DROP SHARPLY, IMPEDING PRONOUNCED INTENSIFICATION OF THE SYSTEM. ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM 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: TROPICAL DEPRESSION 09W WILL CONTINUE GRADUAL CONSOLIDATION AND INTENSIFICATION AS IT TRACKS SLOWLY TO THE NORTHWEST IN A MARGINALLY FAVORABLE ENVIRONMENT UNDER WEAK STEERING FLOW. OVER THE NEXT 24 HOURS IT WILL TRACK AWAY FROM THE INFLUENCE OF THE NEAR EQUATORIAL RIDGE AND GRADUALLY COME UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE, BENDING TO A MORE WESTERLY TRACK. THE SYSTEM WILL INTENSIFY STEADILY, REACHING A PEAK INTENSITY WHILE TRACKING SOUTH OF OKINAWA. COOLER WATERS AND INCREASING SUBSIDENCE ALOFT WILL IMPEDE SHARP INTENSIFICATION. MODEL DISCUSSION: ALTHOUGH GUIDANCE HAS TIGHTENED CONSIDERABLY DURING THE PAST 24 HOURS, THERE REMAINS CONSIDERABLE SPREAD IN MODEL GUIDANCE DURING THE TAU 96-120 HOUR PERIOD. A SIGNIFICANT PORTION OF ENSEMBLE MEMBERS ARE STILL TAKING A POLEWARD TRACK TOWARDS AN UPPER LEVEL LOW SETTLING SOUTH OF KYUSHU, BUT ENSEMBLE MEANS HAVE CONSOLIDATED TOWARDS A TRACK CLOSE TO AND SOUTH OF OKINAWA. THE COMPLEX UPPER AIR PATTERN STEMMING FROM THE MONSOON GYRE WILL ACT TO INCREASE UNCERTAINTY AND MODEL SPREAD THROUGHOUT THE FORECAST, ESPECIALLY IN THE LATER TAUS. THE INTENSITY GUIDANCE IS BACKING DOWN SLIGHTLY WITH EACH CONSECUTIVE MODEL RUN AND ANIMATED WATER VAPOR IMAGERY SUPPORTS THEIR ASSESSMENT OF AN INCREASINGLY UNFAVORABLE ENVIRONMENT UPSTREAM, BUT ALL GUIDANCE IS FIRM IN SHOWING A VIGOROUS TYPHOON STRENGTH SYSTEM AS IT APPROACHES THE RYUKUS. THE JTWC INTENSITY FORECAST STAYS IN THE CENTER OF THE ENSEMBLE MEAN THROUGHOUT THE FORECAST. STATISTICAL DYNAMICAL MODELS REMAIN BELOW THE MEAN AFTER TAU 72, AND NO GUIDANCE INDICATES AN INTENSITY OVER 90KTS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN