WDPN32 PGTW 240300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 19W /WARNING NR 22// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 240000Z6 TO 300000Z3 AUG 2004. A. SUPER TYPHOON (STY) 19W (CHABA), LOCATED APPROXIMATELY 445 NM SOUTH OF IWO JIMA, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 232330Z3 MULTI-SPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 140 AND 155 KNOTS. B. STY 19W IS FORECAST TO TRACK AROUND THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL STEERING RIDGE ANCHORED TO THE NORTH. THE RIDGE WILL WEAKEN AS A MAJOR SHORTWAVE TROUGH PASSES OVER THE TOP ALLOWING FOR STY 19W TO TRANSITION TO A MORE POLEWARD TRACK AFTER TAU 48. THE AVAILABLE DYNAMIC AIDS CONSISTING OF UKMET EGRR, JGSM, TTYM, NOGAPS, COAMPS, NCEP GFS, GFDN, TCLAPS, AND WBAR ARE IN GOOD AGREEMENT WITH THIS SCENARIO FOR THE FIRST 72 HOURS. JGSM AND NCEP GFS ARE THE OUTLIERS WITH A NORTHWESTWARD TRACK. NCEP GFS MAINTAINS THE RIDGE OVER JAPAN FORCING STY 19W TO TRACK IN A MORE NORTHWESTWARD DIRECTION AND JGSM INDICATES A SLIGHT WEAKNESS IN THE RIDGE. THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS. C. STY 19W CONTINUES TO EXPERIENCE GOOD RADIAL OUTFLOW WITH STRONG EQUATORWARD OUTFLOW SO THE SYSTEM HAS MAINTAINED STY STRENGTH WINDS FOR OVER 24 HOURS. THE LATEST STATISTICAL GUIDANCE SHOWS THAT STY 19W WILL BEGIN TO SLOWLY WEAKEN WITH TIME. D. CURRENT WIND AND FORECASTED WIND RADII ARE BASED ON CLIMATOLOGY FOR A LARGE SIZED SYSTEM. E. THE EXTENDED FORECAST CALLS FOR TY 19W TO TRACK POLEWARD AFTER TAU 72 AND CONTINUE TO WEAKEN AS IT MOVES INTO A LESS FAVORABLE ENVIRONMENT AS IT ENCOUNTERS INCREASED VERTICAL WIND SHEAR. 3. FORECAST TEAM: PITTS/MENEBROKER/FUNK/SCHULTZ// NNNN