WDPN31 PGTW 151500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (SURIGAE) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 02W (SURIGAE), LOCATED APPROXIMATELY 80 NM NORTHEAST OF KAYANGEL, PALAU, HAS TRACKED WESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A LARGE CONVECTIVE BUILD UP DIRECTLY OVER THE LOW-LEVEL CIRCULATION CENTER (LLCC) COMPLETELY OBSCURING THE POSITION OF THE LLCC. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A 1509591Z SSMIS 37GHZ IMAGE THAT REVEALS A PARTIAL MICROWAVE EYE ON THE EASTERN EDGE OF THE SCAN, HOWEVER THIS WAS THE BEST RECENT IMAGE AVAILABLE TO INFORM POSITIONING. THE INITIAL INTENSITY IS 55 KTS BASED ON THE DVORAK CURRENT INTENSITY ESTIMATES OF T3.5 (55KTS) BY PGTW AND KNES AND A SATCON OF 53KTS, HEDGING BELOW THE ADT OF 3.9 (63KTS) THAT MAY BE SLIGHTLY INFLATED BASED ON THE RECENT INCREASE IN CONVECTION. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL TO FAVORABLE ENVIRONMENT FOR DEVELOPMENT IN THE SHORT-TERM WITH LOW TO MODERATE (10-20KT) VERTICAL WIND SHEAR (VWS) AND OUTFLOW ALOFT CONTAINED TO THE WESTERN SEMICIRCLE WITH PRESSURE ON THE EASTERN SIDE OF THE STORM. VERY WARM (29-30C) SEA SURFACE TEMPERATURE (SST) IN THE PHILIPPINE SEA IMPROVE THE OVERALL ENVIRONMENT FOR DEVELOPMENT. TS 02W IS CURRENTLY MOVING VERY SLOWLY, TRACKING ALONG THE SOUTHWEST PERIPHERY OF AN EXTENSION OF THE DEEP LAYER SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 02W IS FORECAST TO TRANSITION FROM A WESTERLY TRACK TO A NORTHWESTWARD TRACK BY TAU 48 AS A MIDLATITUDE TROUGH DIGS IN BREAKING THE EXTENSION OF THE STR ALLOWING TS 02W TO TRACK TOWARD THIS WEAKNESS IN THE STR. THE SYSTEM WILL STEADILY INTENSIFY AS THE PRESSURE ON THE EASTERN SIDE SUBSIDES BETWEEN TAUS 12 AND 24 LEADING TO RADIAL OUTFLOW THAT WILL SIGNIFICANTLY IMPROVE THE ENVIRONMENT FOR DEVELOPMENT, WITH TS 02W REACHING 95KTS BY TAU 48 AND 115KTS BY TAU 72. NUMERICAL MODEL GUIDANCE HAS SPREAD SLIGHTLY OVER THE PAST SIX HOURS WITH CROSS-TRACK SPREAD OF 170NM AT TAU 72 WITH ECMWF, ECMWF ENSEMBLE MEAN, GFS, AND UM TRACKING FURTHER WEST BEFORE RECURVING AND NAVGEM, GALWEM, GFS ENSEMBLE MEAN, AND UM ENSEMBLE MEAN RECURVING MORE QUICKLY. THE JTWC TRACK HAS BEEN PLACED NEAR THE MULTI-MODEL CONSENSUS BUT HEDGED TOWARD THE FORMER ENVELOPE OF MODEL SOLUTIONS, THERE IS STILL HIGH CONFIDENCE IN THE EARLY PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, THE BREAK IN THE STR RESULTS IN THE STR TO THE EAST TAKING OVER AS THE PRIMARY STEERING MECHANISM SENDING TS SURIGAE POLEWARD AS IT TRACKS AROUND THE WESTERN PERIPHERY OF THIS RIDGE. THE ENVIRONMENTAL CONDITIONS WILL BECOME SLIGHTLY LESS FAVORABLE AS THE AMOUNT OF UPPER-LEVEL DIVERGENCE DECREASES SIGNIFICANTLY THROUGH THE END OF THE FORECAST PERIOD. THE SYSTEM WILL DECREASE JUST SLIGHTLY TO 110KTS AT TAU 96 AND THEN TO 100KTS AT THE END OF THE FORECAST PERIOD. NUMERICAL MODEL CROSS-TRACK SPREAD IS 450NM AT TAU 120 AS THE TWO SOLUTIONS DESCRIBED ABOVE DIVERGE FURTHER, LENDING LOW CONFIDENCE TO THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.// NNNN