UNCLAS //N03145// MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W WARNING NR 09// RMKS/ WDPN32 PGTW 210300 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 211200Z6 TO 241200Z9 MAY 03. A. TROPICAL STORM (TS) 04W, LOCATED APPROXIMATELY 140 NM NORTHWEST OF CHUUK, HAS TRACKED NORTHWESTWARD AT 04 KNOTS OVER THE LAST 06 HOURS. THE WARNING POSITION IS BASED ON 202330Z0 ENHANCED INFRARED SATELLITE IMAGERY AND A 210021Z6 AIR FORCE WC130 RECON REPORT. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 35, 45 AND 55 KNOTS. LATEST ANIMATED ENHANCED INFRARED SATELLITE IMAGERY REVEALS TS 04W CONTINUES TO CONSOLIDATE WITH GOOD INFLOW AND WELL-DEFINED BANDING FEATURES. THE DEEP CONVECTION CONTINUES TO PERSIST SOUTHWEST OF THE LOW LEVEL CIRCULATION CENTER. B. TS 04W IS CURRENTLY TRACKING POLEWARD ON THE WESTERN PERIPHERY OF A MID-LEVEL RIDGE TO THE NORTHEAST AND IS STEERING TOWARDS A WEAKNESS IN THE SUBTROPICAL RIDGE. THIS WEAKNESS WILL BE ENHANCED BY THE APPROACH OF A MAJOR SHORTWAVE CURRENTLY MOVING OUT OF JAPAN. TS 04W IS ALSO EXPECTED TO BUILD A PERIPHERAL RIDGE TO THE EAST AS IT INTENSIFIES, REINFORCING THE POLEWARD TRACK. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, GFDN, NCEP (GFS), EGGR, JGSM, COAMPS AND MM5 ARE IN GOOD AGREEMENT WITH THIS SCENARIO. WHILE GFDN HAS BECOME MORE POLEWARD, IT REMAINS AN OUTLIER PROJECTING A STRONGER STEERING RIDGE TO BUILD DURING THE MID-FORECAST PERIOD TRANSITIONING TS 04W FROM A POLEWARD TO A MORE WESTWARD TRACK. THIS FORECAST IS BASED ON PERSISTENCE AND A BLEND OF THE AVAILABLE DYNAMIC AIDS WITH LESS EMPHASIS ON GFDN. C. THE SYSTEM IS EXPECTED TO CONTINUE INTENSIFY FOR THE ENTIRE FORECAST PERIOD AS IT TRANSITS THE DIFFLUENT SOUTHWEST QUADRANT OF THE RIDGE. THE UPPER LEVEL ENVIRONMENT IS EXPECTED TO REMAIN FAVORABLE WITH GOOD EQUATORWARD AND POLEWARD OUTFLOW; VERTICAL SHEAR IS EXPECTED TO REMAIN WEAK. D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN INTENSIFYING AVERAGE-SIZED SYSTEM, AND PERSISTENCE. FORECAST TEAM: GRUBER/HEATH/EDBERG/ALLEN//