MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 31W (YUTU) WARNING NR 32// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 31W (YUTU), LOCATED APPROXIMATELY 281 NM EAST- NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE USING ANIMATED MULTISPECTRAL SATELLITE IMAGERY WHICH SHOWS A PARTIALLY CLOUD-FILLED 26 NM EYE. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THAT CLOUD TOP TEMPERATURES IN THE EYEWALL HAVE COOLED OVER THE PAST SEVERAL HOURS. THE 90 KNOT INTENSITY ESTIMATE IS CONSISTENT WITH PGTW/RJTD DVORAK CURRENT INTENSITY ESTIMATES OF T5.0 (90 KNOTS) AND REFLECTS A PAUSE IN THE WEAKENING TREND. THE SYSTEM IS IN A MARGINALLY FAVORABLE REGION WITH LOW (10- 15 KNOT) VERTICAL WIND SHEAR (VWS) AND WARM (28-29 CELSIUS) SEA SURFACE TEMPERATURE BEING PARTIALLY OFFSET BY WEAK RADIAL OUTFLOW. TY 31W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF AN EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 31W WILL CONTINUE ON A WESTWARD TO WEST-SOUTHWESTWARD TRACK AND MAKE LANDFALL ON LUZON SHORTLY AFTER TAU 12 WITH AN INTENSITY OF ABOUT 85 KNOTS. AFTER MAKING LANDFALL, LAND INTERACTION WILL WEAKEN THE SYSTEM SIGNIFICANTLY BEFORE IT EXITS LUZON INTO THE SOUTH CHINA SEA (SCS) SHORTLY AFTER TAU 24. ONCE IN THE SCS, AN APPROACHING MID- LATITUDE TROUGH WILL CREATE A BREAK IN THE STR AND ALLOW THE CYCLONE TO TURN NORTHWARD AND RE-INTENSIFY TO 80 KNOTS BY TAU 72. MODEL GUIDANCE IS IN TIGHT AGREEMENT WITH A 65NM SPREAD AT TAU 48 AND A 165NM SPREAD AT TAU 72. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE CONSENSUS TRACK WITH LOW UNCERTAINTY IN THIS PORTION OF THE JTWC FORECAST. C. AFTER TAU 72, TY 31W WILL CREST THE STR AXIS AND TRACK MORE EAST-NORTHEASTWARD. HIGH VWS AND COOL CONTINENTAL AIR WILL REDUCE THE INTENSITY TO 30 KNOTS BY TAU 120. AS IS COMMON WITH A RECURVING TROPICAL CYCLONE, SPREAD IN THE MODEL GUIDANCE INCREASES SIGNIFICANTLY AS THE DEGREE AND TIMING OF THE TURNING VARIES AMONG THE MODELS. IN THE LATEST RUN, JGSM, COAMPS-GFS, AND (TO SOME DEGREE) HWRF ARE NOT PREDICTING RECURVATURE BEFORE TAU 120 AND DEPICT A MORE NORTHWESTWARD TRACK TOWARDS CHINA. THE REMAINING MODELS ALL DEPICT A RECURVING TRACK, SIMILAR TO THE JTWC TRACK FORECAST. THE SPREAD BETWEEN THE SOUTHERNMOST (COAMPS-GFS) AND NORTHERNMOST (GALWEM) MODELS IS OVER 800 NM BY TAU 120, REFLECTING HIGH UNCERTAINTY IN THE EXTENDED JTWC TRACK FORECAST.// NNNN NNNN