MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 34W (MAN-YI) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 34W (MAN-YI), LOCATED APPROXIMATELY 31 NM NORTH- NORTHWEST OF PULUWAT, HAS TRACKED WEST-NORTHWESTWARD AT 20 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS DEEP CENTRAL CONVECTION, RADIAL OUTFLOW, AND EXTENSIVE RAIN BANDS, PARTICULARLY IN THE NORTHEAST QUADRANT. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE BASED ON A 210626Z GMI 36 GHZ MICROWAVE IMAGE WHICH SHOWED DEEP CONVECTION TO THE NORTHWEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC) WITH BANDING FEATURES EVIDENT IN ALL QUADRANTS EXCEPT THE SOUTHEASTERN ONE. THE INITIAL INTENSITY OF 55 KNOTS IS HEDGED ABOVE THE PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T3.0 (45 KNOTS) FROM PGTW AND KNES BECAUSE OF A 202152Z CIMSS SATCON ESTIMATE OF 59 KNOTS. LOW (10-15 KNOT) VERTICAL WIND SHEAR (VWS), RADIAL OUTFLOW, AND WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURE (SST) MAKE THE SURROUNDING ENVIRONMENT FAVORABLE. TS 34W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. IN THE EXTENDED PERIOD, THE TRACK HAS SHIFTED WESTWARD TO REFLECT THE COLLECTIVE CHANGE IN THE NUMERICAL MODEL GUIDANCE. B. THROUGH TAU 48, THE STR WILL CONTINUE STEERING TS 34W WEST- NORTHWESTWARD. BY TAU 72, AN APPROACHING MID-LATITUDE TROUGH WILL CREATE A WEAKNESS IN THE STR AND TEMPORARILY TURN THE TRACK NORTHWARD. THOUGH TAU 36, FAVORABLE ENVIRONMENTAL CONDITIONS WILL ALLOW THE SYSTEM TO STEADILY INTENSIFY TO 95 KNOTS. AFTER TAU 36, HIGH VWS WILL BEGIN A WEAKENING TREND. MODEL GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH TAU 72, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE JTWC FORECAST TRACK. C. BEYOND TAU 72, TS 34W WILL BECOME QUASI-STATIONARY AND TURN WESTWARD AS THE STR BUILDS BACK IN BEHIND THE MID-LATITUDE TROUGH. HIGH VWS AND UPPER LEVEL CONVERGENCE, ACCOMPANIED BY DRY AIR ENTRAINMENT, ARE EXPECTED TO CONTINUE WEAKENING THE CYCLONE THROUGH THE REMAINDER OF THE FORECAST PERIOD. EVERY MEMBER OF THE CONSENSUS PREDICTS THE WESTWARD TURN AT THE END OF THE PERIOD, ALTHOUGH THE TRACKS SHOW SOME VARIABILITY. THE JTWC TRACK FORECAST HAS BEEN ADJUSTED TO CAPTURE THIS SLOW WESTWARD TURN. BASED ON THE EVOLVING SYNOPTIC ENVIRONMENT IN THE EXTENDED PERIOD, CONFIDENCE IS LOW IN THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.// NNNN NNNN