MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (DOLPHIN) WARNING NR 17// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 07W (DOLPHIN), LOCATED APPROXIMATELY 135 NM NORTHEAST OF POHNPEI, HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY CONTINUES TO DEPICT AN ELONGATED SIGNATURE WITH CURVED BANDING WRAPPING INTO A SLOWLY-CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC). A 101628Z SSMI MICROWAVE IMAGE REVEALS BROKEN CONVECTIVE BANDING OVER WITH THE BULK OF THE DEEP CONVECTION DISPLACED WESTWARD. THE CURRENT POSITION IS BASED ON EXTRAPOLATION FROM A 101451Z GCOM AND 101628Z SSMI IMAGERY. THE INITIAL INTENSITY REMAINS AT 40 KNOTS BASED ON AN OLDER 101124Z ASCAT PASS SHOWING 35 TO 40 KNOT CIRCULATION WITH 45 KNOT WIND BARBS ALONG THE SOUTHERN PERIPHERY. UPPER-LEVEL CONDITIONS REMAIN MARGINAL WITH EASTERLY DIFFLUENT FLOW ALOFT AND MODERATE (20 TO 25 KNOTS) VERTICAL WIND SHEAR (VWS). HOWEVER, SEA SURFACE TEMPERATURES ABOVE 29 CELSIUS REMAIN CONDUCIVE FOR DEVELOPMENT. TS 07W IS TRACKING SLOWLY POLEWARD TOWARDS A BREAK IN THE STEERING SUB-TROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 07W WILL CONTINUE TO TRACK POLEWARD OVER THE NEXT 12 HOURS AS AN UPPER-LEVEL TROUGH PASSES TO THE NORTH CAUSING THE BREAK IN THE STEERING STR. AFTERWARD, THE STR WILL REBUILD AND TURN TS 07W ON A WEST-NORTHWESTWARD TRAJECTORY. UPPER-LEVEL CONDITIONS WILL REMAIN MARGINAL OVER THE NEXT 48 HOURS LEADING TO A MODEST INTENSIFICATION. BEYOND TAU 48, AN IMPROVING ENVIRONMENT, WITH LOW VWS (05 TO 10 KNOTS) AND AN INCREASING POLEWARD OUTFLOW CHANNEL WILL LEAD TO AN INCREASED INTENSIFICATION RATE. C. IN THE EXTENDED TAUS, TS DOLPHIN WILL REMAIN ON A WEST- NORTHWESTWARD TRACK UNDER THE STEERING INFLUENCE OF THE STR. BY THE END OF THE FORECAST PERIOD ANOTHER APPROACHING MID-LATITUDE TROUGH WILL CAUSE THE STEERING STR TO WEAKEN AGAIN, ALLOWING TS 07W TO TURN SLIGHTLY POLEWARD TOWARDS A BREAK IN THE STR. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE AND SUPPORT FURTHER INTENSIFICATION. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT REGARDING THE TRACK AND OVERALL SPEED, LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST.// NNNN NNNN