WDPN31 PGTW 131500 MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (HAIYAN) WARNING NR 9// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 131200Z7 TO 161200Z0 OCT 01. A. TROPICAL STORM (TS) 25W (HAIYAN) LOCATED APPROXIMATELY 580 NM SOUTHEAST OF TAIPEI, TAIWAN, HAS BEEN QUASISTATIONARY DURING THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 131130Z9 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 45 KNOTS. ANIMATED VISIBLE SATELLITE IMAGERY DEPICTS BUILDING DEEP CONVECTION OVER THE LOW LEVEL CIRCULATION CENTER AND MINIMAL CONVECTION IN THE EASTERN SEMICIRCLE. ANIMATED WATER VAPOR IMAGERY DEPICTS A MIGRATORY TUTT CELL TO THE EAST OF TS 25W. THE 200 MB ANALYSIS INDICATES THAT UPPER LEVEL CONVERGENCE MAY BE CONTRIBUTING TO THE LACK OF CONVECTION SEEN IN THIS AREA. B. TS 25W IS CURRENTLY SITUATED WITHIN A WEAKENED RIDGE FLOW PATTERN OF THE SUBTROPICAL RIDGE. THE SHORTWAVE TROUGH PUSHING THROUGH CENTRAL JAPAN IS FORECAST TO PULL OUT DURING THE NEXT 36 HOURS AND ALLOW THE RIDGE TO BUILD IN ACROSS THE PATH OF TS 25W. THEREFORE, TS 25W IS EXPECT TO TRACK SLOWLY NORTHWESTWARD THROUGH THE 36 HOUR POINT AND THEN TRACK WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE BUILDING RIDGE. THE AVAILABLE DYNAMIC AIDS ARE SPLIT INTO TWO CLUSTERS. THE FIRST, CONSISTING OF THE UKMET OFFICE GLOBAL (EGRR), THE JMA GLOBAL (JGSM) AND TYPHOON (JTYM) MODELS DEPICTS A SLIGHTLY LARGER AND INTENSE SYSTEM. THESE MODELS ALSO DEVELOP A PERIPHERAL RIDGE THE SOUTHEAST AND TRACK THE SYSTEM NORTHWESTWARD. NOGAPS (NGPS) AND THE GEOPHYSICAL FLUID DYNAMICS-NAVY (GFDN) MODELS ARE STILL WEST AND EQUATORWARD OF THE FIRST CLUSTER. GFDN AND NGPS FIELDS SHOW INDICATIONS OF EXCESSIVE INTERACTION WITH THE MONSOON TROUGH EXTENDING ACROSS THE SOUTH CHINA SEA. THE FORECAST IS BASED ON AN ENSEMBLE CONSENSUS OF THE AFOREMENTIONED MODELS AND PERSISTENCE. C. TS 25W IS EXPECTED TO INTENSIFY AT A RATE SLOWER THAN CLIMATOLOGY THROUGH THE FORECAST PERIOD DUE TO THE NEGATIVE EFFECTS OF COLD AIR MOVING OFF THE CONTINENT. D. WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE TROPICAL CYCLONE AND SYNOPTIC REPORTS. FORECAST TEAM: SMITH/MAYER/TON// BT #XXXX NNNN