WDPN31 PGTW 010300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 30W /WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 010000Z1 DEC TO 060000Z6 DEC 2004. A. TYPHOON (TY) 30W (NANMADOL), LOCATED APPROXIMATELY 340 NM WEST-NORTHWEST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 24 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 292330Z9 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 102 AND 115 KNOTS. B. TY 30W IS FORECAST TO CONTINUE TO TRACK RAPIDLY WEST- NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE CENTRED TO THE NORTHEAST. TY 30W IS FORECAST TO MAKE LANDFALL ALONG THE EAST COAST OF THE NORTHERN PHILIPPINES AT APPROXIMATELY TAU 36. TY 30W WILL TRACK ACROSS THE NORTHERN PHILIPPINES INTO THE SOUTH CHINA SEA WHERE IT WILL TURN POLEWARD IN RESPONSE TO A DEVELOPING WEAKNESS IN THE STEERING RIDGE CENTERED TO THE NORTHEAST OF THE SYSTEM. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, COAMPS, GFDN, NCEP GFS, JGSM, JTYM, TCLAPS, UKMET, AND WBAR ARE IN FAIR AGREEMENT WITH THIS SCENARIO. THE TIMING OF THE ONSET OF RECURVATURE VARIES AMONG DYNAMIC AIDS BEYOND APPROXIMATELY TAU 48. NCEP AVN DEPICTS A STRONGER MID-LATITUDE TROUGH AND MORE MERIDIONAL DEVELOPMENT OF THE STEERING RIDGE TO THE NORTHEAST AND THEREFORE TRACKS TY 30W POLEWARD FASTER AS COMPARED TO OTHER AIDS. THIS FORECAST IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS. C. THE INTENSITY OF TY 30W IS FORECAST TO INCREASE AT AN APPROXIMATELY CLIMATOLOGICAL RATE THROUGH TAU 36 IN AN ENVIRONMENT OF LOW TO MODERATE VERTICAL WIND SHEAR BALANCED BY GOOD RADIAL OUTFLOW. THE INTENSITY IS FORECAST TO DECREASE SLOWLY AFTER TAU 36 AS THE SYSTEM INTERACTS WITH LAND AND ENTERS AN ENVIRONMENT OF STRONGER VERTICAL WIND SHEAR. D. CURRENT WIND RADII ARE BASED ON A 300902Z4 QUIKSCAT PASS AND A 302132Z1 SSMI MICROWAVE PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR A LARGE SIZED SYSTEM. E. THE MID-LATITUDE TROUGH PROPGATING EASTWARD OVER CHINA WILL PROVIDE A WEAKNESS IN THE STEERING RIDGE LATER IN THE FORECAST PERIOD THAT WILL ALLOW TY 30W TO TURN POLEWARD AFTER TAU 48. TY 30W WILL WEAKEN IN INTENSITY AFTER TAU 72 AS IT ENCOUNTERS INCREASED VERTICAL WIND SHEAR IN THE SOUTH CHINA SEA. TY 30W IS FORECAST TO BEGIN THE INITIAL STAGES OF EXTRATROPICAL TRANSITION BEYOND TAU 72 AS IT TRACKS NORTHEASTWARD AND BECOMES EMBEDDED IN THE MID-LATITUDE WESTERLIES. 3. FORECAST TEAM: DIXON/FJELD/SCHULTZ//