MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (HALONG) WARNING NR 008// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 24W (HALONG), LOCATED APPROXIMATELY 381 NM SOUTH OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CENTRAL DENSE OVERCAST FEATURE, WHICH IS OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). HOWEVER, A 040622Z SSMIS 91GHZ IMAGE INDICATES A WELL-DEFINED MICROWAVE EYE FEATURE, WHICH SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 80 KNOTS BASED ON A PGTW DVORAK INTENSITY ESTIMATE OF T4.5 (77 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW, ENHANCED POLEWARD OUTFLOW AND LOW VERTICAL WIND SHEAR. SST VALUES NEAR 29C ARE ALSO CONDUCIVE FOR FURTHER DEVELOPMENT. TY 24W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. THE 34-KNOT AND 50-KNOT WIND RADII HAVE BEEN ADJUSTED BASED ON A DETAILED ANALYSIS OF RECENT ASCAT IMAGERY. B. TY 24W WILL TRACK NORTHWESTWARD TO NORTH-NORTHWESTWARD THROUGH TAU 36 THEN GRADUALLY RECURVE AS IT ROUNDS THE STR AXIS NEAR TAU 48. AFTER TAU 48, TY 24W WILL ACCELERATE NORTH-NORTHEASTWARD AND IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) BY TAU 72 WHEN IT INTERACTS WITH THE MIDLATITUDE WESTERLIES. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT THROUGH TAU 72 WITH SOME UNCERTAINTY IN THE TIMING OF THE RECURVE. THE SYSTEM WILL INTENSIFY UNDER FAVORABLE CONDITIONS TO A PEAK OF 115 KNOTS BY TAU 36 DUE TO IMPROVED POLEWARD OUTFLOW INTO THE MIDLATITUDE WESTERLIES. C. IN THE EXTENDED PERIOD, TY 24W WILL ACCELERATE NORTHEASTWARD AS IT TRACKS WITHIN THE MIDLATITUDE WESTERLIES AND SHOULD COMPLETE ETT BY TAU 120. HOWEVER, THE SYSTEM IS FORECAST TO SLOW AFTER TAU 120 AS IT ENCOUNTERS A STRONG, LOW-LEVEL MIDLATITUDE HIGH, WHICH MAY TURN THE SYSTEM MORE POLEWARD. TY 24W WILL WEAKEN RAPIDLY DUE TO INCREASING VWS AND COOLER SST. WITH THE EXCEPTION OF NVGI AND AFUI, THE NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH THE TRACK AND TIMING OF THE RECURVE, THEREFORE, THERE IS MODERATE OVERALL CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN