WDPN31 PGTW 311500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (HALONG) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (HALONG), LOCATED APPROXIMATELY 266 NM WEST- NORTHWEST OF NAVSTA GUAM, HAS TRACKED WESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) REVEALS INCREASING DEEP CONVECTION AS A CENTRAL DENSE OVERCAST FEATURE HAS DEVELOPED WHICH HAS OBSCURED THE PREVIOUSLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). A 311037Z SSMIS MICROWAVE IMAGE SHOWS AN INCREASE IN CONSOLIDATION AS DEEP CONVECTIVE BANDING HAS BECOME MORE DEFINED WHILE BEGINNING TO WRAP TIGHTER INTO THE LLCC. THE INITIAL POSITION IS BASED UPON THE MICROWAVE IMAGE AND A POSITION FIX FROM PGTW WITH GOOD CONFIDENCE. THE INITIAL INTENSITY HAS BEEN INCREASED TO 50 KNOTS DUE TO THE INCREASE IN CONSOLIDATION WHILE DVORAK CURRENT INTENSITY ESTIMATES REMAIN AT 45 KNOTS FROM PGTW AND RJTD. UPPER LEVEL ANALYSIS, ALONG WITH WATER VAPOR IMAGERY, DEPICTS STRONG (25 TO 30 KNOTS) VERTICAL WIND SHEAR (VWS) CONTINUES TO ACT UPON THE SYSTEM, WHICH IS SLIGHTLY BEING OFFSET BY VIGOROUS EQUATORWARD OUTFLOW AS THE CONVECTION CONTINUES TO GROW. TS 11W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 11W IS EXPECTED TO TRACK WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 36. AFTER TAU 36, THE STR IS EXPECTED TO MODIFY AND WEAKEN WHICH WILL ALLOW FOR A TRANSITION INTO A MORE NORTHWESTWARD TRACK THROUGH TAU 72. THE STRONG EQUATORWARD OUTFLOW, DESPITE THE NORTHERLY VWS, WILL ALLOW FOR A GRADUAL INTENSIFICATION REACHING 95 KNOTS BY TAU 72. C. TS HALONG IS EXPECTED TO TRACK NORTH-NORTHWESTWARD ALONG THE WEAKENED PERIPHERY OF THE STR IN THE EXTENDED TAUS AND SLOWLY WEAKEN AS IT TRACKS INTO NORTHERLY UPPER-LEVEL FLOW AND VWS ASSOCIATED WITH A BROAD UPPER-LEVEL HIGH TO THE NORTHWEST. NUMERIC MODEL GUIDANCE IS IN FAIRLY TIGHT AGREEMENT THROUGH TAU 48 AND SLIGHTLY DIVERGES AFTER WHICH WITH SOME DISAGREEMENT IN THE EXTENT OF THE RIDGE AS IT MODIFIES AND WEAKENS. DUE TO THIS UNCERTAINTY IN THE MOVEMENT OF THE RIDGE, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST.// NNNN