WDPN31 PGTW 081500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (NOUL) WARNING NR 23// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 06W (NOUL), LOCATED APPROXIMATELY 415 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. TY 06W CONTINUES TO TRACK WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE NORTH. THE CURRENT POSITION IS BASED ON A 081132Z PGTW SATELLITE EYE FIX AND A 081012Z SSMIS IMAGE. THE INTENSITY OF 105 KNOTS IS CONSISTENT WITH DVORAK SATELLITE CURRENT INTENSITY ESTIMATES FROM MULTIPLE REPORTING AGENCIES. RECENT ANIMATED INFRARED SATELLITE IMAGERY SHOWS A NEARLY SYMMETRIC CENTRAL CONVECTIVE PATTERN SURROUNDING A 14 NM EYE. UPPER-LEVEL ANALYSIS INDICATES LOW VERTICAL WIND SHEAR AND FAVORABLE WESTWARD AND EQUATORWARD OUTFLOW ALOFT. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 06W WILL CONTINUE TO TRACK GENERALLY WEST-NORTHWESTWARD UNDER THE CONTINUED STEERING INFLUENCE OF THE SUBTROPICAL RIDGE OVER THE NEXT 36 HOURS, MAKING LANDFALL IN NORTHEASTERN LUZON AROUND TAU 36. THEREAFTER, TY 06W WILL ROUND THE WESTERN PERIPHERY OF THE STEERING RIDGE AHEAD OF AN APPROACHING MID-LATITUDE TROUGH. ADDITIONAL INTENSIFICATION IS ANTICIPATED PRIOR TO LANDFALL UNDER THE FAVORABLE INFLUENCES OF LOW VERTICAL WIND SHEAR, INCREASING POLEWARD OUTFLOW, AND PASSAGE OVER AN AREA OF HIGH OCEAN HEAT CONTENT. STEADY WEAKENING IS ANTICIPATED IN THE 48 TO 72 HOUR TIMEFRAME DUE TO LAND INTERACTION AND INCREASING VERTICAL WIND SHEAR AHEAD OF THE AFOREMENTIONED MID-LATITUDE TROUGH. NUMERIC MODELS REMAIN IN GENERALLY GOOD AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC TRACK FORECAST. C. IN THE EXTENDED PERIOD, TY 06W WILL ACCELERATE NORTHEASTWARD AHEAD OF THE DEVELOPING MID-LATITUDE TROUGH. THE SYSTEM WILL COMPLETE EXTRATROPICAL TRANSITION AND WEAKEN STEADILY DURING THIS PERIOD DUE TO INCREASING VERTICAL WIND SHEAR, DECREASING ALONG-TRACK SEA SURFACE TEMPERATURES, AND DRY AIR ENTRAINMENT. NUMERIC MODELS ARE IN FAIR AGREEMENT REGARDING TRACK DIRECTION BUT TRACK SPEEDS DIVERGE SIGNIFICANTLY IN THE EXTENDED PERIOD. THIS PORTION OF THE JTWC TRACK FORECAST LIES SLIGHTLY AHEAD OF THE MULTI-MODEL CONSENSUS BASED ON EXPECTATIONS OF VERY STRONG STEERING FLOW. GIVEN NOTED MODEL SPREAD, EXTENDED RANGE TRACK FORECAST CONFIDENCE IS LOW.// NNNN