WDPN31 PGTW 260300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 03W (SONCA) /WARNING NR 23// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 260000Z8 TO 270000Z9 APR 2005. A. TYPHOON (TY) 03W (SONCA), LOCATED APPROXIMATELY 495 NM SOUTHWEST OF IWO JIMA, HAS TRACKED NORTHEASTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED WATER VAPOR IMAGERY SHOWS THE SYSTEM BECOMING INCREASINGLY ASYMMETRIC AS IT UNDERGOES EXTRATROPICAL TRANSITION. B. TY 03W HAS CRESTED THE AXIS OF THE SUBTROPICAL RIDGE AND IS ACCELERATING NORTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE. TY 03W IS FORECAST TO CONTINUE ACCELERATING NORTH- EASTWARD AND BECOME EMBEDDED IN THE MID-LATITUDE FLOW. THE CURRENT SPEED IS LESS THAN PREVIOUSLY FORECAST DUE TO A WEAKER TROUGH OVER EASTERN ASIA. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, GFDN, COAMPS, AVN, JGSM, JTYM, EGRR, MM5 AND WBAR ARE IN GOOD AGREEMENT WITH THIS SCENARIO. THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS. C. TY 03W HAS BEGUN TO WEAKEN DUE TO DRY AIR ENTRAINMENT AND INCREASED VERTICAL WIND SHEAR ASSOCIATED WITH THE MID-LATITUDE WESTERLIES. TY 03W HAS BEGUN TRANSITION TO AN EXTRATROPICAL CYCLONE, AND IS FORECAST TO COMPLETE THIS TRANSITION BY TAU 24. D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED SYSTEM UNDERGOING EXTRATROPICAL TRANSITION. 3. FORECAST TEAM: CHARLIE// NNNN