WDPN32 PGTW 071500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (SIXTEEN) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.0N 147.0E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 340 NM NORTH-NORTHEAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 13 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM (TS) 16W HAS RAPIDLY CONSOLIDATED AND QUALITATIVELY IMPROVED IN OVERALL STRUCTURAL APPEARANCE OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN IRREGULAR CENTRAL DENSE OVERCAST (CDO) FEATURE, WITH UPPER-LEVEL CIRRUS FORMING TRANSVERSE BANDS ALONG THE EASTERN SIDE OF THE CDO, INDICATIVE OF STRONG UPPER-LEVEL OUTFLOW IN THESE REGIONS. ANIMATED WATER VAPOR IMAGERY AND CIRA DERIVED MOTION VECTOR (DMV) PRODUCTS CONTINUE TO INDICATE A WEAK TUTT-CELL POSITIONED APPROXIMATELY 450NM NORTHWEST OF TS 16W AND A SECOND TUTT-CELL POSITIONED APPROXIMATELY 950NM TO THE EAST. UPPER-LEVEL WINDS ARE NORTHEASTERLY ACROSS THE REGION SURROUNDING TS 16W, BUT THE FLOW SPLITS NEAR THE SYSTEM, WITH A PORTION HEADING POLEWARD INTO THE EAST SIDE OF THE TUTT-CELL, AND THE OTHER PORTION HEADING EQUATORWARD. ADDITIONALLY. A FORTUITOUS 071150Z ASCAT-C BULLSEYE REVEALED THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS MOVED FURTHER UNDER THE CDO THAN ORIGINALLY THOUGHT AND PROVIDED HIGH CONFIDENCE TO THE INITIAL POSITION. THE SAME ASCAT PASS REVEALED 35 KNOT WINDS IN THE SOUTHEASTERN QUADRANT OF THE ROTATION, CONFIRMING THE PGTW T2.5 INTENSITY ESTIMATE AS WELL AS THE BULK OF THE OBJECTIVE INTENSITY ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE, WITH LOW NORTHEASTERLY VWS, VERY WARM SSTS AND MODERATE EQUATORWARD AND POLEWARD OUTFLOW. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T1.5 - 25 KTS KNES: T2.0 - 30 KTS CIMSS SATCON: 35 KTS AT 070844Z CIMSS ADT: 33 KTS AT 071140Z CIMSS AIDT: 34 KTS AT 071140Z CIMSS D-MINT: 29 KTS AT 070832Z CIMSS D-PRINT: 33 KTS AT 071210Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE POLEWARD AND EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 16W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG THE SOUTHWESTERN FLANK OF THE STRONG STR OVER THE NEXT 24 HOURS. THE SYSTEM WILL GRADUALLY TURN ONTO A WESTWARD TRACK BETWEEN TAU 36 AND TAU 48 AS THE RIDGE BUILDS WESTWARD AND ULTIMATELY MERGES WITH A SMALL STR CENTERED NEAR OKINAWA, CREATING A MASSIVE, DEEP, SOUTHWEST-NORTHEAST ORIENTED STR THAT EXTENDS FROM COASTAL CHINA TO THE DATELINE. TS 16W WILL TRAVEL WESTWARD ALONG THE SOUTHERN FLANK OF THIS RIDGE THROUGH TAU 72, BEFORE DIPPING SLIGHTLY SOUTHWESTWARD AROUND TAU 96 AS THE RIDGE MOVES TO A POSITION SOUTHEAST OF HONSHU. AFTER TAU 96, TS 16W WILL BEGIN TRACKING MORE WEST-NORTHWESTWARD DUE TO SLIGHT CHANGES IN THE ORIENTATION OF THE RIDGE AS IT CONTINUES TO MOVE TOWARDS THE WEST. TS 16W HAS ALREADY INTENSIFIED MORE THAN ORIGINALLY EXPECTED BY THIS TIME IN THE FORECAST. UNFORTUNATELY, THE LACK OF RECENT MICROWAVE IMAGERY PRECLUDES A CONCRETE ANALYSIS OF THE LOW-LEVEL STRUCTURE, WHICH IS OBSCURED UNDER THE CDO. THE ASCAT PASS WOULD SUGGEST THE LOW-LEVEL VORTEX HAS BECOME BETTER ALIGNED. HOWEVER, ASSUMING THIS IS TRUE, THE SYSTEM SHOULD BE ABLE TO STEADILY INTENSIFY OVER THE NEXT 24-48 HOURS. A FASTER RATE OF INTENSIFICATION IS FORECAST AFTER TAU 48 AS THE SYSTEM MOVES OVER A POOL OF RELATIVELY HIGH OHC WATERS. WHILE DEEP-LAYER SHEAR IS EXPECTED TO INCREASE SLIGHTLY BEGINNING AS EARLY AS TAU 48, THE SYSTEM AT THAT POINT SHOULD BE STRONG ENOUGH TO RESIST, AT LEAST FOR ABOUT 24 HOURS. BEGINNING AROUND TAU 72, SHEAR IS EXPECTED TO INCREASE SHARPLY (UP TO ABOUT 25- 30 KTS), AND BE ACCOMPANIED BY DRY AIR INTRUSION. THE COMBINATION OF FACTORS WILL PUT A LID ON INTENSIFICATION FOR ABOUT 24 HOURS, AND MAY INDUCE SOME WEAKENING. AFTER TAU 96, THE SYSTEM ONCE AGAIN MOVES INTO A LOWER SHEAR ENVIRONMENT AND WILL RESUME ITS INTENSIFICATION TREND THROUGH THE END OF THE FORECAST PERIOD. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL TRACK SCENARIO OF A NORTHWESTWARD, THEN WESTWARD, TRAJECTORY. CROSS-TRACK SPREAD INCREASES TO 230NM BY TAU 72, BETWEEN THE EGRR ON THE NORTH SIDE OF THE ENVELOPE AND THE GFS ON THE SOUTHERN EDGE. HOWEVER, THE EGRR LOSES THE VORTEX AFTER TAU 72, AND IS SUCH A SIGNIFICANT OUTLIER, THAT IT HAS BEEN DISCARDED FROM THE CONSENSUS. THE REMAINDER OF THE CONSENSUS MEMBERS SHOW A MORE SUBDUED SPREAD OF 160NM AT TAU 72. BY TAU 120 THE CROSS-TRACK SPREAD INCREASES TO 400NM, WITH NAVGEM NOW TAKING THE PLACE OF THE EGRR IN BEING A MARKED OUTLIER TO THE NORTH, TAKING THE SYSTEM OVER OKINAWA. AGAIN, THIS IS UNREALISTIC, AND NAVGEM IS KNOWN TO HAVE A POLEWARD BIAS AND THUS HAS BEEN DISCARDED FROM THE CONSENSUS. THE REMAINDER OF THE GUIDANCE PACKAGE IS SPREAD ACROSS A 220NM ENVELOPE AT TAU 120, WITH THE ECMWF ON THE NORTH SIDE AND GFS ON THE SOUTH. ENSEMBLE GUIDANCE CONTINUES TO BE CONSISTENT WITH THE TRACK SCENARIO AND THE JTWC FORECAST WITH UNCERTAINTY DECREASING IN BOTH THE GEFS AND ECENS OVER THE PAST COUPLE OF RUNS. THE JTWC FORECAST IS PLACED ON THE SOUTHERN SIDE OF THE ENVELOPE AND IS CONSISTENT WITH THE GEFS AND EC-AIFS TRACKERS. INTENSITY GUIDANCE REMAINS CONSISTENT WITH THE LAST COUPLE OF RUNS, WITH THE MESOSCALE GUIDANCE FAR OUTPACING THE DECAY-SHIPS. HOWEVER, THE PEAKS HAVE FOR THE MOST PART BACKED OFF A BIT WITH THIS RUN, EXCEPT FOR THE COAMPS-TC (GFS) WHICH INSISTS THIS IS GOING TO BE A SUPER-TYPHOON ONE DAY. THE HAFS-A PEAK HAS DROPPED TO 95 KNOTS. THE JTWC FORECAST IS PLACED NEAR THE HAFS-A THROUGH TAU 96, THEN CLOSE TO THE COAMPS-TC TRACKER THEREAFTER. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN