WDPN31 PGTW 111500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (SIX) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.1N 140.2E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 62 NM WEST-NORTHWEST OF IWO TO MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) IMAGERY REVEALS THAT TROPICAL DEPRESSION (TD) 06W REMAINS QUASI-STATIONARY. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON A WELL-DEFINED, PREDOMINANTLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) APPARENT IN THE INFRARED IMAGERY, AS WELL AS A 111159Z METOP-B ASCAT PASS. INCREASING AND MODERATE (15-20 KTS) NORTHWESTERLY VERTICAL WIND SHEAR (VWS) IS PUSHING THE CENTRAL CONVECTION TOWARDS MODERATELY STRONG EQUATORWARD OUTFLOW CHANNEL. THE AFOREMENTIONED ASCAT PASS ALSO REVEALS AN ASYMMETRIC WIND FIELD STRUCTURE, WITH MAXIMUM WINDS PRESENT THROUGHOUT THE EASTERN SEMICIRCLE OF THE CIRCULATION. THE SYSTEM CONTINUES TO LACK SUSTAINED DEEP CONVECTION OVER THE LLCC, LIKELY DUE TO THE SUPPRESSIVE INFLUENCE OF AN UPPER-TROPOSPHERIC TROUGH POSITIONED DIRECTLY ALOFT. THE INITIAL INTENSITY IS EVALUATED AT 30 KTS WITH HIGH CONFIDENCE, SUPPORTED BY DVORAK ESTIMATES, OBJECTIVE SATELLITE-BASED INTENSITY GUIDANCE, AS WELL AS THE 111159Z ASCAT PASS. ADDITIONAL ENVIRONMENTAL ANALYSIS SUGGESTS MARGINALLY FAVORABLE CONDITIONS FOR DEVELOPMENT. DEEP-LAYER MOISTURE CONTENT REMAINS MODERATE TO HIGH, SEA SURFACE TEMPERATURES RANGE FROM 28 TO 29 C, AND THE SYSTEM LIES JUST NORTH OF AN UPPER-LEVEL DIFFLUENT ZONE ENHANCING EQUATORWARD OUTFLOW. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: COMPETING STEERING BETWEEN THREE RIDGING AREAS - TO THE NORTHWEST, SOUTHWEST AND EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T1.0 - 25 KTS KNES: T1.5 - 25 KTS CIMSS ADT: 31 KTS AT 111140Z CIMSS AIDT: 34 KTS AT 111140Z CIMSS D-PRINT: 28 KTS AT 111230Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: UPPER LEVEL TROUGH LOCATED OVER THE SYSTEM ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH 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: TD 06W REMAINS QUASI-STATIONARY DUE TO ITS POSITION WITHIN A SYNOPTIC COL REGION, BOUNDED BY SUBTROPICAL RIDGING TO THE NORTHWEST, SOUTHWEST AND EAST OF THE SYSTEM. CONSEQUENTLY, THE SYSTEM IS EXPECTED TO EXHIBIT MINIMAL TRANSLATION OVER THE NEXT 24 HOURS AS THE STEERING PATTERN GRADUALLY EVOLVES. AROUND TAU 24, THE SUBTROPICAL RIDGE (STR) TO THE EAST IS FORECAST TO BUILD SIGNIFICANTLY AND ASSUME THE PRIMARY STEERING, FACILITATING A GRADUAL NORTHWARD ACCELERATION OF THE SYSTEM. INTENSITY IS PROJECTED TO INCREASE MODESTLY, PEAKING AROUND 50 KTS BY TAU 48. HOWEVER, FURTHER INTENSIFICATION WILL LIKELY BE CONSTRAINED BY PROGRESSIVE ENTRAINMENT OF DRY MID-LEVEL AIR INTO THE CORE CIRCULATION. BEYOND TAU 72, THE SYSTEM WILL BEGIN TO INTERACT WITH AN APPROACHING MID-LATITUDE LONGWAVE TROUGH, LEADING TO INCREASED BAROCLINIC FORCING. EXTRATROPICAL TRANSITION IS ANTICIPATED TO COMMENCE AROUND TAU 72 AND COMPLETE BY TAU 96, AS THE SYSTEM BECOMES EMBEDDED WITHIN THE MID- LATITUDE FLOW. MODEL DISCUSSION: TRACK GUIDANCE FROM NUMERICAL MODELS HAS IMPROVED SINCE THE LAST FORECAST AND EXHIBITS FAIR CONSENSUS REGARDING THE INITIAL QUASI-STATIONARY MOTION, FOLLOWED BY A GENERAL POLEWARD PROGRESSION AND EVENTUAL NORTHEASTWARD RECURVATURE. CROSS-TRACK SPREAD AT TAU 36 IS ESTIMATED AT 50 NM, EXPANDING TO 140 NM BY TAU 72. GALWEM AND UKMET SOLUTIONS REMAIN THE OUTLIERS, HOWEVER BOTH MODELS HAVE NOW JOINED THE REMAINDER OF THE CONSENSUS MEMBERS IN PROJECTING A NORTH TO NORTHEASTWARD TRACK, WITH THEIR SOLUTIONS TRACKING FURTHER WEST THAN THE MAIN GROUPING. AS A RESULT, THE JTWC TRACK FORECAST IS ISSUED WITH MEDIUM CONFIDENCE AND LIES CLOSE TO THE TIGHTENING MULTI-MODEL CONSENSUS RESULT. INTENSITY GUIDANCE ALSO DEMONSTRATES GENERAL AGREEMENT, WITH A MODEST INTENSIFICATION TREND EXPECTED THROUGH TAU 48, FOLLOWED BY WEAKENING DUE TO ENVIRONMENTAL DEGRADATION. PEAK INTENSITY SPREAD IS STILL ESTIMATED AT 20 KTS, WITH NAVGEM-DRIVEN COAMPS-TC NOW BEING THE MOST CONSERVATIVE MODEL PROJECTING STRONGEST WINDS OF 40 KTS, AND HAFS REMAINING THE HIGHEST PROJECTION, WITH 60 KTS MAXIMUM INTENSITY. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN