WDPN31 PGTW 210300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W /WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 210000Z3 TO 260000Z8 SEP 2004. A. TROPICAL STORM (TS) 25W (MEARI), LOCATED APPROXIMATELY 180 NM WEST OF GUAM, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 202330Z0 MULTI-SPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 35 AND 45 KNOTS. B. TS 25W IS TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE MID-LEVEL STEERING RIDGE. DURING THE MID-FORECAST PERIOD AN APPROACHING TROUGH TRACKING EASTWARD OVER CHINA WILL CREATE A WEAKNESS IN THE STEERING RIDGE AND ALLOW TS 25W TO TRACK MORE POLEWARD. THE AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, GFDN, UKMET EGRR, JGSM, JTYM, NCEP GFS, COAMPS AND WBAR ARE IN FAIR AGREEMENT WITH THIS FORECAST SCENARIO. HOWEVER, THE NCEP GFS FORECASTS A STRONGER BREAK AND A MORE INTENSE VORTEX RESULTING IN GREATER POLEWARD MOTION AT THE MEDIUM-RANGE (72-120 H). THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMICAL AIDS. C. TS 25W IS FORECAST TO INTENSIFY AT A LESS-THAN CLIMATOLOGICAL RATE THROUGHOUT THE FORECAST. THE POTENTIAL FOR ENHANCED POLEWARD OUTFLOW INTO AN UPPER-LEVEL LOW TO THE NORTHEAST OF THE SYSTEM EXISTS. THIS ENHANCED OUTFLOW COULD RESULT IN STRONGER INTENSIFICATION OF TS 25W. HOWEVER, A CLEAR OUTFLOW LINKAGE HAS NOT YET BEEN OBSERVED. THE SYSTEM IS TRACKING IN AN ENVIRONMENT OF LOW VERTICAL WIND SHEAR AND GOOD UPPER LEVEL POLEWARD OUTFLOW. HOWEVER, DRY AIR AHEAD OF THE STORM IS INHIBITING INTENSIFICATION. ALL AIDS INDICATE INTENSIFICATION AT A SLOWER THAN CLIMATOLOGICAL RATE THROUGHOUT THE FORECAST PERIOD. D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR A LESS THAN AVERAGE SIZED SYSTEM. E. TS 25W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE. STRONG DISAGREEMENT IN THE EXTENDED FORECAST TRACK EXISTS BETWEEN THE NCEP GFS AND THE OTHER MODELS IN THE CONSENSUS. THE GFS DEPICTS A MORE PRONOUNCED WEAKNESS IN THE STEERING RIDGE AND A MORE POLEWARD TRACK. CONFIDENCE IN THE EXTENDED FORECAST TRACK IS LOW. 3. FORECAST TEAM: DIXON/FIORINO/MENEBROKER/FUNK/JAYKOWSKI// NNNN