MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (PRAPIROON) WARNING NR 38// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 22W (PRAPIROON), LOCATED APPROXIMATELY 215 NM SOUTH-SOUTHEAST OF KADENA AIR BASE, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY CONTINUES TO DEPICT WEAKENING CENTRAL CONVECTION BUT HAS RETAINED EXTENSIVE CONVECTIVE BANDING AROUND A LARGE TIGHTLY-WRAPPED AND WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL INTENSITY WAS ASSESSED AT 55 KNOTS, WHICH IS SLIGHTLY HIGHER THAN DVORAK CURRENT INTENSITY ESTIMATES FROM RJTD, KNES AND PGTW, DUE TO THE WELL DEFINED STORM STRUCTURE SEEN IN A 161859Z AMSU 89 GHZ MICROWAVE IMAGE. UPPER LEVEL ANALYSIS AND ANIMATED WATER VAPOR IMAGERY REVEAL THE SYSTEM CONTINUES TO MAINTAIN NEAR RADIAL OUTFLOW AND IS IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION AND CURRENT MOTION BASED UPON THE IR LOOP AND THE MICROWAVE IMAGE. TS 22W HAS STARTED TO MAKE THE TURN TO THE NORTH AS SEEN IN THE RECENT NORTHWESTWARD MOTION AS A MID-LATITUDE TROUGH DIGS IN FROM EASTERN CHINA AND THE SUBTROPICAL RIDGE BECOMES MORE EAST-WEST ORIENTED. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 22W IS FORECAST TO TRACK SLOWLY MORE NORTHWARD IN THE NEXT 12 HOURS, AND BEGIN TO TURN NORTHEASTWARD UNDER THE STEERING INFLUENCE OF THE STR AND ACCELERATE AS A MIDLATITUDE SHORTWAVE TROUGH CONTINUES TO DIG IN FROM EASTERN CHINA. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 72 WITH SOME SLIGHT DISAGREEMENT WITH ALONG TRACK SPEEDS. THE JTWC FORECAST IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS AND IS HIGHLY CONSISTENT WITH THE PREVIOUS FORECAST. TS 22W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY THROUGH TAU 24 DUE TO THE RADIAL OUTFLOW AND GENERALLY FAVORABLE CONDITIONS. NEAR TAU 48, TS 22W IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT BEGINS TO INTERACT WITH THE BAROCLINIC ZONE. C. IN THE EXTENDED TAUS, TS 22W IS EXPECTED TO COMPLETE ETT BY TAU 72 AND ACCELERATE NORTHEASTWARD AS IT BECOMES EMBEDDED WITHIN THE STRONG MIDLATITUDE WESTERLY FLOW. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE ENTIRE JTWC FORECAST TRACK.// NNNN NNNN