WDPN31 PGTW 010300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (CHATAAN) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 010000Z1 TO 040000Z4 JUL 02. A. TROPICAL STORM (TS) 08W (CHATAAN), LOCATED APPROXIMATELY 220 NM EAST-SOUTHEAST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 06 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON A 302228Z7 TROPICAL RAINFALL MEASURING MISSION (TRMM) PASS AND 302330Z1 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 45 AND 55 KNOTS. ANIMATED WATER VAPOR IMAGERY REVEALS THAT AN UPPER LEVEL LOW CENTERED NEAR 22.6N0 152.7E5 CONTINUES TO PROVIDE FAVORABLE POLEWARD OUTFLOW. THE 302228Z7 TRMM PASS SHOWS THAT THE DEEP CONVECTION REMAINS ON THE EAST SIDE OF THE LOW LEVEL CIRCULATION CENTER (LLCC). B. TS 08W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO NORTHWESTWARD UNDER THE INFLUENCE OF THE MID-LEVEL HIGH HEIGHT CENTER BUILDING TO THE NORTH-NORTHEAST. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NCEP AVIATION, NOGAPS, GFDN, AFWA MM5, COAMPS, UKMET GLOBAL (EGRR), AND JAPANESE GLOBAL (JGSM) AND TYPHOON (JTYM) MODELS ARE IN GOOD AGREEMENT WITH THIS SCENARIO. OUR FORECAST IS BASED ON A BLEND OF PERSISTENCE AND A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS. C. THE UPPER LEVEL LOW TO THE NORTH IS EXPECTED TO DRIFT WEST AND CONTINUE TO PROVIDE A POLEWARD OUTFLOW CHANNEL FOR THE SYSTEM AT LEAST THROUGH EARLY-PERIOD. UPPER LEVEL ANALYSIS ALSO REVEALS POINT SOURCE DIFFLUENCE OVER THE CENTER PROVIDING ENHANCED OUTFLOW. THE STORM IS EXPECTED TO REMAIN IN A FAVORABLE ENVIRONMENT, THEREFORE IT SHOULD DEVELOP AT A CLIMATOLOGICAL RATE THROUGH THE FORECAST PERIOD. D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE SYSTEM. FORECAST TEAM: BRYANT/JACOBS/RONSSE/SHERRY// NNNN