MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (HAIKUI) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 12W (HAIKUI), LOCATED APPROXIMATELY 130 NM EAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS CENTRAL CONVECTION HAS BEEN FLARING OVER THE LOW LEVEL CIRCULATION CENTER FOR THE PAST 12 HOURS. PREDOMINANTLY THE DEEPEST CONVECTION IS LOCATED WITHIN THE SOUTHERN SEMI-CIRCLE, AS BROKEN BANDS EXTENDING THROUGHOUT THE SOUTHWESTERN QUADRANT. THE RADAR DEPICTION FROM OKINAWA SHOWS A MULTITUDE OF BANDS CROSSING OVER OKINAWA AND INTO THE EAST CHINA SEA. UPPER LEVEL ANALYSIS INDICATES TS 12W IS LOCATED TO THE SOUTH OF A DEEP LAYERED SUBTROPICAL RIDGE (STR) AND IS TRACKING ALONG ITS SOUTHERN PERIPHERY. ANIMATED WATER VAPOR IMAGERY AND TOTAL PRECIPITABLE WATER CONTINUE TO INDICATE TS 12W IS PARTIALLY ENCAPSULATED BY A WEAKENING RIBBON OF DRY AIR ALONG THE WESTERN AND SOUTHERN SEMI-CIRCLES. ADDITIONALLY, THE VERTICAL WIND SHEAR (VWS) REMAINS LOW (05 TO 10 KNOTS). THE OUTFLOW REMAINS MARGINAL OVER THE ENTIRE SYSTEM. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 12W IS FORECAST TO MAINTAIN A WEST-NORTHWESTWARD TRACK ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH TAU 72. INTENSIFICATION WILL REMAIN SLOW AND STEADY UNDER WEAK VWS AND WARM (28-30C) SEA SURFACE TEMPERATURES TO A PEAK OF 80 KNOTS BY TAU 72. MODEL GUIDANCE HAS SLOWLY COME INTO BETTER AGREEMENT THROUGH TAU 72, WITH NGPS AND GFDN CONTINUING TO SHOW A TIGHT POLEWARD TURN BY TAU 72. THERE IS HIGH CONFIDENCE IN THE TRACK FORECAST THROUGH TAU 72. C. TS 12W IS EXPECTED TO MAKE LANDFALL AS A SIGNIFICANT TYPHOON SHORTLY AFTER TAU 72. DISSIPATION WILL BEGIN BY TAU 96 AS FRICTIONAL DRAG INCREASES. MODEL GUIDANCE HAS BEEN IMPROVING HOWEVER THERE CONTINUES TO BE A LARGE SPREAD AFTER TAU 72. WITH THE EXCEPTION OF NGPS AND GFDN DISCUSSED EARLIER, THE REMAINDER OF THE GUIDANCE KEEPS TS 12W OVER LAND. A RELATIVELY SHALLOW MID-LATITUDE TROUGH WILL INTERACT WITH THE STEERING STR OVER THE NEXT TWO TO THREE DAYS BUT AT THIS TIME THE MAGNITUDE OF INTERACTION REMAINS UNCLEAR. ADDITIONALLY, ANOTHER SHALLOW MID-LATITUDE TROUGH WILL AGAIN INTERACT WITH THE STR BY THE FOUR TO FIVE DAY MARK, WHICH IS DEPICTED WITHIN THE FORECAST BY THE SLIGHT NORTHWESTWARD TRACK AT TAU 120. DUE TO THE HIGH LEVEL OF UNCERTAINTY THE TRACK FORECAST CONFIDENCE REMAINS LOW.// NNNN NNNN