MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (MEARI) WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 26W (MEARI), LOCATED APPROXIMATELY 641 NM SOUTH- SOUTHWEST OF IWO TO, JAPAN, HAS TRACKED NORTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A CONSOLIDATING CYCLONE WITH EXPANDING FEEDER BANDS WRAPPING INTO A DEFINED LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION IS PLACED AMIDST A CLUSTER OF AGENCY FIXES WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON OBJECTIVE AND AGENCY DVORAK ESTIMATES RANGING FROM T2.5 TO T3.3 AND REFLECTS THE SLIGHT INTENSIFICATION. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS IN A FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW AND LOW (5-10 KNOT) VERTICAL WIND SHEAR (VWS). TS MEARI IS TRACKING TOWARD A WEAKNESS BETWEEN TWO SUBTROPICAL HIGHS (STH) - ONE TO THE NORTHWEST AND THE OTHER TO THE NORTHEAST OF THE SYSTEM. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS MEARI IS EXPECTED TO TRACK SLOWLY ON A MORE NORTH- NORTHEASTWARD TRAJECTORY TOWARD A WEAKNESS BETWEEN THE TWO STH FEATURES. STEADY INTENSIFICATION OF THE SYSTEM IS ALSO FORECAST AS OUTFLOW CONTINUES TO IMPROVE AND VWS REMAINS FAVORABLE NEAR THE STR AXIS, PEAKING AT 75 KNOTS BY TAU 72. C. AFTER TAU 72, ONCE PASSED THE STR AXIS, TS MEARI WILL BEGIN TO ACCELERATE NORTHEASTWARD AS A DEEPENING MID-LATITUDE TROUGH APPROACHES FROM THE NORTHWEST. THE SYSTEM WILL ALSO BEGIN TO WEAKEN AS VWS INCREASES WITHIN THE DEEP, PREVAILING WESTERLIES. TS 26W IS FORECAST TO UNDERGO EXTRA-TROPICAL TRANSITION IN THE LATER TAUS, AS IT INTERACTS WITH THE UPPER-LEVEL TROUGH AND A TIGHT THICKNESS GRADIENT, BECOMING A COLD-CORE LOW BY END OF FORECAST. DYNAMIC MODEL GUIDANCE CONTINUES TO CONSOLIDATE WITH GFDN AS THE SOLE WESTERN OUTLIER, LENDING FAIR CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN