WDPN33 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (NALGAE) WARNING NR 17// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 13W (NALGAE), LOCATED APPROXIMATELY 662 NM NORTHEAST OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED NORTHWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS BECOME MORE SHALLOW AND FURTHER SHEARED NORTHWARD OF A BROAD AND RAGGED LOW-LEVEL CIRCULATION. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND FROM A LOW REFLECTIVITY CIRCULATION FEATURE IN THE 2339Z SSMIS MICROWAVE PASS WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON CONGRUENT DVORAK ESTIMATE OF T2.5 FROM PGTW AND RJTD. UPPER-LEVEL ANALYSIS INDICATES AN INCREASINGLY UNFAVORABLE ENVIRONMENT WITH SOUTHERLY VERTICAL WIND SHEAR OFFSET BY POLEWARD OUTFLOW. TS 13W IS TRACKING ALONG THE WESTERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST TRACK PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS NALGAE IS FORECAST TO CONTINUE TRACKING NORTH TO NORTH- NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR THROUGH THE FORECAST PERIOD. TS 13W HAS DRIFTED INTO COOLER SSTS AND BEGUN EXTRA- TROPICAL TRANSITION. THE SYSTEM WILL BECOME A 30-KNOT COLD-CORE LOW BY TAU 24. DYNAMIC GUIDANCE REMAINS IN TIGHT AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN