WDPN31 PGTW 070300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (HAGUPIT) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 7.2N 143.8E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 365 NM EAST-SOUTHEAST OF YAP MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 15 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: AS DEPICTED IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI), TROPICAL STORM (TS) 05W (HAGUPIT) EXHIBITS PRONOUNCED ASYMMETRY, WITH PERSISTENT DEEP CONVECTION LOCATED ALONG THE EASTERN PERIPHERY. NASCENT CONVECTION IS ORGANIZING ALONG THE WESTERN AND SOUTHWESTERN PERIPHERY OF THE LOW-LEVEL CIRCULATION CENTER (LLCC) ALONG A LOW- LEVEL CONVERGENCE BOUNDARY. THE MOST RECENT MICROWAVE DATA RECEIVED WAS A 062003Z SSMIS PASS, IN WHICH THE 91GHZ IMAGE REVEALED DEFINITIVE LOW-LEVEL BANDING FEATURES, THOUGH DEEP CONVECTION REMAINS PRIMARILY LIMITED TO THE EASTERN QUADRANT OF THE CIRCULATION. WHILE ESTABLISHING THE INITIAL POSITION IS CONSTRAINED BY DISORGANIZED FLOW PATTERNS ASSOCIATED WITH OUTFLOW BOUNDARIES IN THE MSI, A 070000Z IN SITU SURFACE OBSERVATION FROM WOLEAI ATOLL INDICATED LIGHT EAST- SOUTHEASTERLY WINDS AND A SURFACE PRESSURE OF 1004MB, PROVIDING HIGH CONFIDENCE THAT THE LLCC IS LOCATED SOUTH-SOUTHWEST OF THE STATION. THE INITIAL INTENSITY IS ASSESSED WITH LOW CONFIDENCE AS A RANGE BETWEEN 30 AND 35 KNOTS, WITH THE COMPOSITE OF OBJECTIVE AND SUBJECTIVE ESTIMATES NOTED BELOW CONSTRAINED BETWEEN THESE VALUES. 070000Z UPPER-AIR ANALYSES FROM YAP AND PALAU INDICATE MODERATE WESTERLY VERTICAL WIND SHEAR (VWS), WITH MAXIMUM SHEAR MAGNITUDE LOCATED IN THE MID-TROPOSPHERE, CONSISTENT WITH THE OBSERVED VERTICAL TILT OF THE VORTEX CORE AS DEPICTED IN THE MODEL FIELDS AND SATELLITE IMAGERY. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE, CHARACTERIZED BY WEAK RADIAL OUTFLOW ALOFT, WARM SSTS, AND WEAK DEEP-LAYER SHEAR. HOWEVER, THESE FACTORS ARE ADVERSELY IMPACTED BY DRY ENTRAINMENT ALONG THE WESTERN FLANK AND MODERATE WEST- SOUTHWESTERLY MID-LEVEL SHEAR. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: LOW TO MID-LEVELS OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T2.0 - 30 KTS RCTP: T2.5 - 35 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 35 KTS AT 062300Z CIMSS ADT: 35 KTS AT 070000Z CIMSS AIDT: 33 KTS AT 070000Z CIMSS D-MINT: 27 KTS AT 062100Z CIMSS D-PRINT: 27 KTS AT 070000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK RADIAL OTHER FACTORS: DRY MID-LEVEL AIR ALONG THE WESTERN FLANK; HIGH MID-LEVEL SOUTHWESTERLY SHEAR. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: LOW INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 05W WILL TRACK WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD ALONG THE SOUTHERN PERIPHERY OF THE DEEP STR POSITIONED FAR TO THE NORTHEAST. THE SYSTEM WILL UNDERGO AN INCREASED POLEWARD COMPONENT OF MOTION WHILE DECELERATING AFTER TAU 72, AS THE STR RECEDES EASTWARD AND THE SYSTEM TRANSITIONS INTO A WEAK STEERING REGIME. TS 05W WILL PASS JUST SOUTH OF YAP AROUND TAU 36 BEFORE TRAVERSING THE PHILIPPINE SEA. REGARDING INTENSITY, THE SYSTEM CONTINUES TO EXHIBIT POOR CONSOLIDATION IN THE FACE OF PERSISTENT MODERATE MID-LEVEL SHEAR AND DRY AIR INTRUSION. GLOBAL AND MESOSCALE MODEL FIELDS SUGGEST NO SIGNIFICANT CHANGES TO THE SYNOPTIC SHEAR REGIME FOR THE NEXT 24 HOURS; CONSEQUENTLY, INTENSITY IS FORECAST TO REMAIN RELATIVELY STEADY THROUGH THIS PERIOD. BY TAU 36, SHEAR IS EXPECTED TO WEAKEN, ESPECIALLY IN THE MID-LEVELS. HOWEVER, WHILE SHEAR TENDENCIES ARE NEGATIVE, DRY AIR ENTRAINMENT WILL PERSIST AS A PRIMARY INHIBITING FACTOR; THUS, TS 05W WILL INTENSIFY ONLY MARGINALLY THROUGH TAU 48. AFTER TAU 48, THE SYSTEM WILL GRADUALLY SUCCUMB TO INCREASING VWS AND CONTINUED DRY AIR ENTRAINMENT DEGRADATION, RESULTING IN CYCLOLYSIS THROUGH THE REMAINDER OF THE FORECAST PERIOD. MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD OVERALL AGREEMENT THROUGH THE ENTIRE FORECAST PERIOD. CROSS-TRACK SPREAD GRADUALLY INCREASES TO 120MM AT TAU 72 AND 250NM BY TAU 120. GFS AND NAVGEM MARK THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE THROUGH THE ENTIRE FORECAST PERIOD, WHILE ECMWF AND EC-AIFS MARK THE SOUTHERN EDGE OF THE ENVELOPE. ENSEMBLE GUIDANCE IS ALSO IN STRONG AGREEMENT ON A WEST-NORTHWESTWARD TRAJECTORY, WITH MINIMAL MODEL DISPERSION THROUGH TAU 120. THE JTWC FORECAST IS ALIGNED WITH THE EXPERIMENTAL AI MODEL AND MULTI-MODEL CONSENSUS MEAN TRACKERS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE EXHIBITS BIMODAL SOLUTIONS. THE WEAKER COHORT INCLUDES GFS, HAFS-A, AND THE EXPERIMENTAL AI MODEL, PREDICTING A PEAK NEAR 40 KNOTS AROUND TAU 48 FOLLOWED BY STEADY DISSIPATION. THE OTHER COHORT, CONSISTING OF HWRF, COAMPS-TC AND DECAY SHIPS, DEPICTS A HIGHER PEAK MAGNITUDE NEAR 50 KNOTS BEFORE RAPIDLY WEAKENING AFTER TAU 72. THE JTWC FORECAST IS HEDGED TOWARD THE CONSENSUS MEAN THROUGH TAU 48, THEN ROUGHLY ANALOGOUS TO THE HWRF TRACKER THROUGH TAU 120, WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN