WDPN31 PGTW 241500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W WARNING NR 12// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 02W (OMAIS), LOCATED APPROXIMATELY 350 NM NORTH-NORTHWEST OF PALAU, HAS RECONSOLIDATED SLIGHTLY AS THE MAIN CONVECTION STACKED CLOSER TO THE LOW LEVEL CIRCULATION CENTER. UPPER LEVEL ANALYSIS INDICATES THE SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) HAS RELAXED WITH THE STORM'S INCREASE IN FORWARD MOTION. THIS IS EVIDENT ON ANIMATED WATER VAPOR IMAGERY SHOWING THE MAIN AREA OF CONVECTION REGAINING SYMMETRY OVER THE PAST SIX HOURS. THE SAME ANIMATION ALSO SHOWS GOOD POLEWARD OUTFLOW AS THE SYSTEM APPROACHES THE STRONG WESTERLIES ASSOCIATED WITH THE SUBTROPICAL JET STREAM. THE CURRENT POSITION AND INTENSITY ARE BASED ON THE DVORAK FIXES FROM PGTW AND RJTD THAT ARE IN CLOSE PROXIMITY WITH INTENSITY VALUES RANGING FROM 35 TO 45 KNOTS. 3. FORECAST REASONING A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SIGNIFICANTLY FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 02W IS FORECAST TO CONTINUE TRACKING ALONG THE SOUTHWEST TO WESTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL STEERING RIDGE THROUGHOUT THE FORECAST PERIOD. BY TAU 24, AN UPPER LEVEL TROUGH APPROACHING FROM THE NORTHWEST WILL WEAKEN THE RIDGE AND ALLOW TS 02W TO TURN MORE POLEWARD. THIS MOTION WILL, HOWEVER, EXPOSE 02W TO INCREASED VWS THAT WILL EVENTUALLY WEAKEN THE SYSTEM. AS THE SYSTEM LOSES STRENGTH AND VERTICAL DEPTH, IT WILL SLOW DOWN, AND EVENTUALLY DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE OVER WATER BY TAU 48. THE NUMERICAL MODELS ARE INITIALLY IN GOOD AGREEMENT BUT THEN BECOME WIDELY SPREAD AFTER TAU 24. GFDN AND ECMWF TRACK THE SYSTEM MORE WESTWARD, FAVORING AN EARLIER EROSION OF THE SYSTEM. GFS AND WBAR ARE TO THE EXTREME RIGHT OF THE ENVELOPE, FAVORING A FASTER AND MORE INTACT SYSTEM BEYOND TAU 48. THIS FORECAST TRACK IS IN AGREEMENT WITH THE JTWC CONSENSUS TO TAU 36 BEFORE IT LAGS BEHIND TO COMPENSATE FOR THE FAST RIGHT-WING OUTLIERS. // NNNN