WDPN31 PGTW 050900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (CHOI-WAN) WARNING NR 027// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 04W (CHOI-WAN), LOCATED APPROXIMATELY 97 NM WEST OF KADENA AB, HAS TRACKED NORTHEASTWARD AT 25 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS CONSISTENT WITH RECENT SATELLITE FIXES FROM PGTW AND RJTD, LOW-LEVEL CONVECTIVE BANDING EVIDENT IN A 050518Z AMSR2 PASS AND ANIMATED RADAR IMAGERY FROM JAPAN. THE INTENSITY OF 35 KNOTS IS BASED ON A CONSENSUS OF SUBJECTIVE DVORAK ESTIMATES RANGING FROM 25 TO 35 KNOTS AND A 050406Z AUTOMATED SATCON ESTIMATE OF 42 KNOTS. TS 04W HAS CONTINUED TO TRACK RAPIDLY NORTHEASTWARD OVER THE PAST SIX HOURS IN THE GRADIENT BETWEEN A SUBTROPICAL STEERING RIDGE TO THE EAST AND A DEEP MIDLATITUDE TROUGH TO THE NORTHWEST. ENVIRONMENTAL CONDITIONS ARE BECOMING INCREASINGLY UNFAVORABLE, WITH MARGINAL SEA SURFACE TEMPERATURES (27-28 CELSIUS) AND HIGH VERTICAL WIND SHEAR (20-25 KNOTS). STRONG UPPER-LEVEL DIVERGENCE HAS FUELED FLARING DEEP CONVECTION TO THE NORTHEAST OF THE CENTER OVER THE PAST FEW HOURS, BUT THE AFOREMENTIONED AMSR2 PASS SHOWS NO COMMENSURATE INCREASE IN LOW-LEVEL ORGANIZATION. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS CHOI-WAN WILL CONTINUE TO TRACK RAPIDLY NORTHEASTWARD IN THE IN THE GRADIENT BETWEEN SUBTROPICAL RIDGING TO THE SOUTHEAST AND THE DEEP TROUGH TO THE NORTHWEST OVER THE NEXT 24 HOURS. RAPIDLY INCREASING VERTICAL WIND SHEAR, DECREASING ALONG-TRACK SEA SURFACE TEMPERATURES AND CONVERGENT FLOW ALOFT WILL DRIVE RAPID DISSIPATION BELOW THE WARNING THRESHOLD INTENSITY OF 25 KNOTS BY TAU 24. THE JTWC FORECAST TRACK LIES NEAR THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE, GIVEN CONTINUED GOOD AGREEMENT AMONG NUMERICAL MODEL SOLUTIONS.// NNNN