WDPN31 PGTW 071500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W /WARNING NR 06// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 03W (AERE), LOCATED APPROXIMATELY 275 NM EAST-SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A SIGNIFICANT INCREASE IN DEEP CENTRAL CONVECTION WITHIN THE PAST 12 HOURS. RECENT MICROWAVE SATELLITE IMAGERY (070936Z SSMIS AND 070825Z SSMI) SHOWS IMPROVED CONVECTIVE BANDING WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION BASED ON INTERPOLATION FROM THE 070825Z SSMIS MICROWAVE IMAGE. THE CURRENT INTENSITY IS BASED ON PGTW, KNES, AND RJTD DVORAK ESTIMATES OF 40 TO 45 KNOTS. WATER VAPOR IMAGERY INDICATES GOOD RADIAL OUTFLOW. TS 03W IS LOCATED JUST SOUTH OF AN UPPER LEVEL ANTICYCLONE IN AN AREA OF LOW VERTICAL WIND SHEAR (VWS). 3. FORECAST REASONING. A. THIS FORECAST IS DIFFERENT FROM THE PREVIOUS FORECAST PHILOSOPHY IN THAT THE SYSTEM RECURVES FASTER AND CROSSES OVER A NARROWER PORTION OF LAND. THEREFORE, THE INTENSITY REMAINS HIGHER. ADDITIONALLY, THE SYSTEM INCREASES IN TRANSLATION SPEED IN THE LATER TAUS AS MODELS HAVE COME MORE INTO AGREEMENT WITH A RECURVATURE SCENARIO. B. TS 03W CONTINUES TO TRACK ALONG THE SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL STEERING RIDGE. THE SYSTEM SHOULD GENERALLY TRACK NORTHWESTWARD AND INTENSIFY UNDER THE LOW VWS, GOOD RADIAL OUTFLOW, AND HIGH SEA SURFACE TEMPERATURES. IT IS THEN EXPECTED TO MAKE LANDFALL OVER THE RUGGED TERRAIN OF LUZON BY TAU 36 AND WEAKEN SLIGHTLY. ONCE BACK OVER WATER IN THE LUZON STRAIGHT, TS 03W SHOULD BEGIN TO ROUND THE RIDGE AXIS AS A PASSING MID-LATITUDE TROUGH WEAKENS THE STEERING RIDGE. AT THIS POINT, OUTFLOW SHOULD INCREASE INTO THE TROUGH, ALTHOUGH INTENSIFICATION WILL BE COUNTERBALANCED BY THE DRY AIR AND HIGHER VWS. NUMERICAL MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT WITH THE RECURVATURE SCENARIO, EXCEPT FOR GFS WHICH CONTINUES TO TRACK THE SYSTEM SLOWLY NORTHWARD ACROSS THE LUZON STRAIGHT. ADDITIONALLY, ECMWF PULLS THE MODEL CONSENSUS FAR EASTWARD AS IT QUICKLY RECURVES THE SYSTEM. THIS FORECAST IS SLOWER THAN MODEL CONSENSUS IN THE LATER TAUS TO ACCOUNT FOR ECMWF. C. AFTER TAU 72, TS AERE WILL CONTINUE TO ROUND THE RIDGE AXIS AND WEAKEN DUE TO INCREASED VWS ASSOCIATED WITH THE MID-LATITUDE TROUGH AND DRY AIR. THE SYSTEM SHOULD BEGIN TO TRANSITION INTO A WEAK EXTRATROPICAL SYSTEM BY TAU 120. BASED ON THE HOSTILE UPPER LEVEL CONDITIONS TS 03W WILL ENCOUNTER AS IT RE-EMERGES IN THE LUZON STRAIGHT, THERE IS A CHANCE DISSIPATION COULD OCCUR SOONER THAN FORECAST.// NNNN