WDPN32 PGTW 121500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (PODUL) WARNING NR 023// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 21.6N 125.0E INITIAL INTENSITY: 80 KTS GEOGRAPHIC REFERENCE: 285 NM SOUTHEAST OF TAIPEI, TAIWAN MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 34 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A SIGNIFICANT IMPROVEMENT IN OVERALL STRUCTURE, WITH A LARGE, ALTHOUGH STILL SOMEWHAT RAGGED, EYE DEVELOPING OVER THE PAST FEW HOURS. BANDS OF RELATIVELY STRONG CONVECTION CONTINUE TO DEVELOP IN A BAND ALONG THE SOUTHERN PERIPHERY OF THE CIRCULATION, AND BRIEFLY WRAP UPSHEAR, BUT HAVE NOT BEEN ABLE TO ESTABLISH A FULLY CLOSED EYEWALL ON THE NORTHEAST SIDE. THIS IS LIKELY DUE TO PERSISTENT NORTHEASTERLY SHEAR, WHICH DUE TO A LACK OF CIMSS DATA IS BASED SOLELY ON MODEL DERIVED DATA. LIKELY THERE IS ENHANCED MID-LEVEL SHEAR FROM THE EAST-NORTHEAST, AS WELL AS SOME LINGERING DRY AIR, BOTH OF WHICH ARE INHIBITING THE CONVECTION FROM FULLY PUSHING UPSHEAR AND ESTABLISHING A SOLID EYEWALL. A 121238Z GMI 37GHZ IMAGE REVEALS A BEAN-SHAPED MICROWAVE EYE, WITH A SOLID EYEWALL IN ALL QUADRANTS SAVE FOR THE NORTH-NORTHEAST SECTOR. THE 89GHZ IMAGE PRETTY MUCH TELLS THE SAME STORY, WITH THE DRYNESS IN THE MID-LEVELS ESPECIALLY PREVALENT IN THE 89GHZ IMAGE. COMPARISON OF THE TWO BANDS REVEALS A SMALL AMOUNT OF VORTEX TILT TO THE WEST-SOUTHWEST. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, HEDGED SLIGHTLY HIGHER THAN THE T4.5 DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES. OF NOTE, CIMSS DATA IS INTERMITTENT AND STRUGGLING TO MAINTAIN A LOCK ON THE TARGET AND IS SIGNIFICANTLY UNDER-ESTIMATING THE CURRENT INTENSITY, BUT RAW ADT VALUES WERE AS HIGH AS T5.4 EARLIER. ENVIRONMENTAL CONDITIONS ARE IN THE AGGREGATE FAVORABLE WITH LOW TO MODERATE DEEP-LAYER SHEAR, WARM SSTS AND MODERATE OUTFLOW ALOFT, OFFSET SOMEWHAT BY THE MORE NEGATIVE FACTORS DISCUSSED ABOVE. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF AN EXTENSIVE SUBTROPICAL RIDGE (STR) COMPLEX EXTENDING FROM SOUTHERN CHINA, SOUTH OF HONSHU AND INTO THE NORTHERN PACIFIC. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T4.0 - 65 KTS RCTP: T5.0 - 90 KTS KNES: T4.5 - 77 KTS CIMSS ADT: 57 KTS AT 121100Z CIMSS AIDT: 67 KTS AT 121100Z CIMSS D-PRINT: 67 KTS AT 121100Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE WESTWARD OTHER FACTORS: WEAK EQUATORWARD OUTFLOW. RELATIVELY DRIER MID-LEVEL AIR IN THE NORTHEASTERN QUADRANT. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON (TY) 16W IS FORECAST TO CONTINUE TRACKING TOWARDS THE NORTHWEST ALONG THE SOUTHERN SIDE OF THE STR TO THE NORTH, THROUGH THE FORECAST PERIOD. AS THE SYSTEM APPROACHES TAIWAN, THE TRACK WILL VERY LIKELY EXHIBIT ERRATIC MOTION, WITH RACK DEFLECTION, EITHER RIGHT OR LEFT OF THE OVERALL TRACK, AS WELL AS SIGNIFICANT DECELERATION. THE AMOUNT OF TRACK DEFLECTION OR DECELERATION WILL IN LARGE PART DEPEND ON THE EXACT LOCATION OF LANDFALL ALONG THE CENTRAL MOUNTAIN RANGE (CMR) AND CANNOT AT THIS TIME BE PREDICTED WITH ANY ACCURACY. ONCE THE SYSTEM DOES MAKE LANDFALL, WITHIN THE NEXT 12 TO 18 HOURS, IT WILL EVENTUALLY PASS OVER THE CMR, AND MOVE INTO THE TAIWAN STRAIT, BEFORE QUICKLY CROSSING THE STRAIT AND MAKING A SECOND LANDFALL ALONG THE SOUTHEASTERN COAST OF CHINA AROUND TAU 30, THEN CONTINUING INLAND INTO SOUTHERN CHINA. IN TERMS OF INTENSITY, THE CONTINUED CYCLING OF CONVECTION ALONG THE SOUTHERN AND SOUTHEASTERN PERIPHERY OF THE VORTEX HAS HELPED PUSH BACK AGAINST THE SHEAR AND ANIMATED WATER VAPOR IMAGERY CONFIRMS THAT THE UPPER-LEVEL FLOW IS SPLITTING AROUND 250NM UPSTREAM OF THE CENTER. THE NEAREST UPPER-AIR SOUNDING FROM ISHIGAKIJIMA SHOWS EASTERLY 200MB WINDS AT 55 KNOTS. COMBINED WITH THE WATER VAPOR IMAGERY, EIR AND MICROWAVE IMAGERY, IT IS ASSESSED THAT THE TIGHT SHEAR GRADIENT IS POSITIONED JUST NORTH OF THE CORE OF TY 16W, WHILE THE CENTER AND THE SOUTHERN HALF IS UNDER THE INFLUENCE OF SMALL-SCALE ANTICYCLONE ALOFT. GOING FORWARD, MODEL FIELDS INDICATE CONTINUED MOISTENING OF THE CIRCULATION, ALONG WITH FURTHER REDUCTION OF SHEAR, ALLOWING FOR ADDITIONAL INTENSIFICATION THROUGH LANDFALL. ONCE THE SYSTEM MOVES ACROSS THE CMR, IT WILL RAPIDLY WEAKEN, WITH THE VORTEX LIKELY DECOUPLING IN THE PROCESS, BEFORE REFORMING IN THE TAIWAN STRAIT. HOWEVER, THE SYSTEM IS NOT EXPECTED TO INTENSIFY IN THE STRAIT, AND IS FORECAST TO MAKE LANDFALL AS A TROPICAL STORM, BEFORE RAPIDLY WEAKENING AND DISSIPATING OVER SOUTHERN CHINA BY TAU 48. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH THE FORECAST PERIOD, WITH JUST 35NM CROSS-TRACK SPREAD AT LANDFALL, INCREASING TO 100NM BY THE END OF THE FORECAST. THE JTWC FORECAST IS PLACED ON THE SOUTHERN EDGE OF GUIDANCE ENVELOPE WITH HIGH CONFIDENCE. WHILE THE MODELS ARE IN TIGHT AGREEMENT, THE ANTICIPATED ERRATIC TRACK MOTION PRIOR TO LANDFALL MAY SIGNIFICANTLY ALTER BOTH THE TIMING AND LOCATION OF LANDFALL AND THE SUBSEQUENT TRACK. INTENSITY GUIDANCE IS ALSO IN TIGHT AGREEMENT AND CONSISTENT WITH THE PREVIOUS GUIDANCE PACKAGE. THE INTERPOLATED HAFS-A AND HWRF CONTINUE TO BE THE MOST AGGRESSIVE, PEAKING THE SYSTEM AT BETWEEN 85 AND 95 KNOTS RESPECTIVELY. MEANWHILE THE NON-INTERPOLATED 06Z RUNS OF BOTH MODELS ARE EVEN MORE AGGRESSIVE, WITH PEAKS AS HIGH AS 115 KNOTS. THE JTWC FORECAST IS PLACED ON THE HIGH EDGE OF THE GUIDANCE, CONSISTENT WITH THE INTERPOLATED HWRF, THEN WEAKENS THE SYSTEM AT A SLIGHTLY FASTER RATE THAN THE BULK OF THE GUIDANCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: MEDIUM// NNNN