MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (HALONG) WARNING NR 024// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 24W (HALONG), LOCATED APPROXIMATELY 293 NM NORTH- NORTHEAST OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED NORTHEASTWARD AT 24 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 080444Z SSMIS 91GHZ IMAGE DEPICT A LARGE AREA OF DEEP CONVECTION SURROUNDING AN APPARENT MICROWAVE EYE FEATURE, LENDING GOOD CONFIDENCE TO THE INITIAL POSITION. UPPER-LEVEL ANALYSIS REVEALS A MARGINALLY UNFAVORABLE ENVIRONMENT WITH MODERATE (20 TO 25 KNOTS) WESTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY CONTINUED, STRONG POLEWARD OUTFLOW. THE CURRENT INTENSITY IS ASSESSED AT 75 KNOTS BASED ON A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF 4.5 (77 KNOTS). TY 24W IS TRACKING WITHIN THE MIDLATITUDE WESTERLY FLOW ALONG THE NORTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY HALONG WILL CONTINUE TO TRACK NORTHEASTWARD AND GRADUALLY TURN EAST-NORTHEASTWARD BY TAU 12. THE ENVIRONMENT WILL BECOME MORE UNFAVORABLE WITH INCREASING VWS AND COOLING SSTS, LEADING TO RAPID WEAKENING. EXTRA-TROPICAL TRANSITION (ETT) WILL BEGIN AT TAU 12 AS TY 24W BEGINS TO INTERACT WITH THE BAROCLINIC ZONE. BY TAU 36 THE SYSTEM WILL COMPLETE ETT AND WEAKEN TO 35 KNOTS. NUMERICAL MODELS ARE IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN