WDPN31 PGTW 170300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (HAIYAN) WARNING NR 23// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 170000Z8 TO 200000Z2 OCT 01. A. TYPHOON (TY) 25W (HAIYAN), LOCATED APPROXIMATELY 80 NM NORTHWEST OF OKINAWA, HAS TRACKED NORTHEASTWARD AT 11 KNOTS DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 172330Z6 INFRARED AND VISIBLE SATELLITE IMAGERY AND AVAILABLE SYNOPTIC AND RADAR DATA. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 65 TO 78 KNOTS. ANIMATED WATER VAPOR IMAGERY REVEALS A SUBTROPICAL RIDGE CENTERED EAST OF THE SYSTEM AND AN EASTWARD MOVING MID-LATITUDE TROUGH OVER NORTHEASTERN CHINA. IMAGERY ALSO REVEALS A LARGE CIRRUS SHIELD INTERACTING WITH THE MID-LATITUDE WESTERLIES. B. TY 25W HAS PASSED NORTH OF THE SUBTROPICAL RIDGE AXIS AND IS NOW TRACKING NORTHEASTWARD UNDER THE STEERING INFLUENCE OF THE MID-LEVEL SUBTROPICAL RIDGE TO THE EAST. THE SYSTEM IS FORECAST TO TRACK NORTHEASTWARD THROUGH THE FORECAST PERIOD UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO THE EAST-SOUTHEAST AND THE MID-LATITUDE WESTERLIES. JMA GLOBAL (JGSM), UK-MET OFFICE (EGRR), NCEP AVIATION (AVN), JMA TYPHOON (JTYM), AND NOGAPS (NGPS) MODELS ARE IN GOOD AGREEMENT, WITH DIRECTION, INDICATING A NORTHEAST TRACK BUT ARE IN POOR AGREEMENT WITH THE SPEED OF ADVANCEMENT. THE JMA TYPHOON AND EGRR MODELS INDICATE A MUCH FASTER SPEED OF ADVANCE. NOGAPS AND GFDN INDICATE A MUCH SLOWER SPEED OF ADVANCE AS THE SYSTEM WEAKENS RAPIDLY AND FAILS TO BE PICKED UP BY THE MID-LATITUDE WESTERLIES. THE FORECAST IS BASED ON PERSISTENCE AND FAVORS THE JGSM, JTYM, NGPS, EGRR, AND AVN CLUSTER. A LOW PROBABILITY SCENARIO EXISTS IN THAT THE SYSTEM WOULD WEAKEN MORE RAPIDLY THAN THE MODELS INDICATE. THIS SCENARIO WOULD CAUSE TY 25W TO BECOME QUASI-STATIONARY AND LOOP BACK TO THE SOUTH AROUND THE 36 HOUR PERIOD UNDER THE STEERING INFLUENCE OF THE LOW-LEVEL RIDGE OVER EASTERN CHINA. THIS SCENARIO FAVORS THE NGPS SOLUTION. C. TY 25W IS EXPECTED TO WEAKEN AS IT ENCOUNTERS INCREASING VERTICAL WIND SHEAR. D. WIND RADII ANALYSIS IS BASED ON A RECENT QUIKSCAT PASS AND SYNOPTIC DATA. FORECAST RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE TROPICAL CYCLONE. FORECAST TEAM: MAZANY/JACOBS/CUTMAN// NNNN