UNCLAS //N03145// MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (NANGKA) WARNING NR 07// RMKS/ WDPN31 PGTW 020300 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 020000Z2 TO 070000Z7 JUN 03. A. TROPICAL STORM (TS) 06W (NANGKA), LOCATED APPROXIMATELY 150 NM SOUTHWEST OF TAIWAN, HAS TRACKED NORTHEASTWARD AT 10 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 012330Z9 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 45 KNOTS. ANIMATED INFRARED SATELLITE IMAGERY REVEALS THAT THE DEEP CONVECTION HAS DECREASED SLIGHTLY IN THE PAST 06 HOURS. B. TS 06W IS FORECAST TO CONTINUE TRACKING TO THE NORTHEAST UNDER THE INFLUENCE OF THE STEERING RIDGE TO THE EAST OF THE SYSTEM FOR THE NEXT 36 HOURS. AFTERWARDS, TRACK SPEED IS FORECAST TO INCREASE FURTHER AS THE SYSTEM FALLS UNDER THE INFLUENCE OF THE MID-LATITUDE WESTERLIES, BEGINNING EXTRATROPICAL TRANSITION BETWEEN 48 AND 72 HOURS. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, UKMET (EGRR), GFDN, THE JAPANESE GLOBAL (JGSM) AND TYPHOON MODELS (JTYM), COAMPS, AFWA MM5 AND NCEP GFS FALL ARE IN GOOD AGREEMENT WITH THIS FORECAST, WITH MOST MODELS MERGING THE SYSTEM INTO THE MID-LATITUDE WESTERLIES BY 96 HOURS. THIS FORECAST IS BASED ON PERSISTENCE AND A CONSENSUS OF ALL THE DYNAMIC AIDS. C. TS 06W REMAINS IN A MODERATE UPPER LEVEL ENVIRONMENT AND WILL DEVELOP AT LESS THAN A CLIMATOLOGICAL RATE OVER THE NEXT 36 HOURS. AFTER THE MID-PERIOD EXTRATROPICAL TRANSITION AND INCREASING VERTICAL WIND SHEAR WILL HALT TROPICAL DEVELOPMENT. D. CURRENT FORECAST WIND RADII ARE BASED ON A RECENT QUIKSCAT PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE- SIZED SYSTEM. E. LONG RANGE FORECAST TRACK BASED ON AN EXTRAPOLATION OF THE DYNAMIC AIDS AND MODEL FIELD EXAMINATION AFTER 72 HOURS. TS 06W (NANGKA) IS FORECAST TO WEAKEN SLIGHTLY AFTER 72 HOURS AND WILL BE EXTRATROPICAL NEAR THE 96 HOUR POINT. FORECAST TEAM: BRYANT/MOHAMMED/WAUGAMAN/DENSON/NUTONGLA// NNNN