MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (SAOLA) WARNING NR 33// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 27W (SAOLA), LOCATED APPROXIMATELY 61 NM SOUTH OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS DEVELOPED A LARGE AND RAGGED BANDING EYE THAT IS NOT QUITE CLOSED. THE DEEP CONVECTIVE BANDS, MOSTLY FEEDING IN FROM THE WEST TO SOUTHWEST HAVE WRAPPED TIGHTER INTO THE LOW LEVEL CIRCULATION. THE INITIAL POSITION IS BASED ON THE MSI AND ON A RADAR COMPOSITE REFLECTIVITY LOOP FROM OKINAWA WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 65 KNOTS IS BASED ON THE PGTW DVORAK ESTIMATE OF T4.0 AND REFLECTS THE UPGRADED STATUS OF TY 27W. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS NOW IN AN AREA OF MODERATE TO STRONG (20-25 KNOT) VERTICAL WIND SHEAR (VWS). THERE IS ALSO STRONG SUBSIDENCE ALONG THE WESTERN SEMI-CIRCLE CAUSED BY THE LEADING EDGE OF A MID-LATITUDE TROUGH DIGGING IN FROM CHINA. IN THE SAME AREA, A ROBUST NORTHERLY LOW LEVEL DRY AIR ENTRAINMENT IS EVIDENT ON THE MSI LOOP. HOWEVER, VERY STRONG EQUATORWARD AND POLEWARD OUTFLOW, ENHANCED BY INITIAL EXPOSURE INTO THE PREVAILING WESTERLIES, PLUS WARM SSTS AT 28 CELSIUS, ARE OFFSETTING THESE NEGATIVE EFFECTS AND CAUSING NEAR-TERM INTENSIFICATION. THE CYCLONE IS ROUNDING THE WESTERN EDGE OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY SAOLA WILL BEGIN TO RECURVE AND ACCELERATE NORTHEASTWARD AS IT GETS EMBEDDED IN THE MID-LATITUDE WESTERLIES. IT WILL PASS OVER EASTERN OKINAWA THEN SKIRT THE SOUTHERN COAST OF MAINLAND JAPAN. THE ENHANCED POLEWARD OUTFLOW WILL PREVAIL AND INTENSIFY 27W TO A PEAK OF 75 KNOTS BY TAU 24. AFTERWARD, THE STRONG WINDS WILL TRANSLATE TO STRONG VWS. ADDITIONALLY, COOL DRY AIR ADVECTION AND COOLING SSTS, CONCURRENT WITH EXTRA-TROPICAL TRANSITION (ETT) BY TAU 36, WILL STEADILY ERODE THE SYSTEM. BY TAU 48, THE SYSTEM WILL BECOME A STORM-FORCE COLD CORE LOW WITH A RAPIDLY EXPANDING WIND FIELD IN THE PACIFIC OCEAN SOUTHEAST OF HOKKAIDO. THE DYNAMIC MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH THE FORECAST TRACK. HOWEVER, AS TYPICAL WITH RECURVE SCENARIOS, THERE IS SIGNIFICANT DIFFERENCES IN THE LATERAL SPEED AMONG THE TRACK MEMBERS. THE TRACK SPEEDS DIFFER EVEN GREATER AT THE ETT PHASE. IN VIEW OF THIS, THERE IS FAIR CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 24, THEN LOW CONFIDENCE AFTERWARD.// NNNN NNNN