WDPN32 PGTW 100300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (NARI) WARNING NR 06// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 24W (NARI), LOCATED APPROXIMATELY 395 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS FURTHER DEEPENED AS THE SYSTEM BECAME MORE SYMMETRIC AND COMPACT. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND FROM AGENCY FIXES WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 60 KNOTS IS BASED ON THE HIGH END DVORAK ESTIMATES FROM PGTW, RJTD, AND KNES TO REFLECT THE DEEPENING TREND. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS APPROXIMATELY 10 DEGREES SOUTH OF THE RIDGE AXIS IN AN AREA OF LIGHT TO MODERATE (10-15 KNOT) EASTERLY VERTICAL WIND SHEAR. HOWEVER, THE SAME EASTERLY FLOW IS ENHANCING WESTWARD OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 24W IS EXPECTED TO TRACK GENERALLY WESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR. THE DYNAMIC MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON A GENERALLY WESTWARD TRACK ACROSS LUZON. THE SYSTEM IS FORECAST TO INTENSIFY TO A PEAK OF 90 KNOTS AS IT APPROACHES LUZON UNDER THE FAVORABLE UPPER LEVEL CONDITIONS IN ADDITION TO WARM SEA SURFACE TEMPERATURES. AFTERWARDS, THE SYSTEM WILL WEAKEN AS IT DRAGS ACROSS THE MOUNTAIN RANGES OF LUZON, THEN EXIT INTO SOUTH CHINA SEA (SCS) SHORTLY AFTER TAU 48. C. IN THE EXTENDED PERIOD, TS NARI WILL CONTINUE TO TRACK WESTWARD ACROSS THE SCS UNDER THE PERSISTENT STEERING INFLUENCE OF THE STR. IT IS EXPECTED TO RE-INTENSIFY AS THE FAVORABLE CONDITIONS DISCUSSED ABOVE RESUME. BASED ON THE TIGHT AGREEMENT OF DYNAMIC MODELS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS LAID VERY CLOSE TO THE MODEL CONSENSUS. // NNNN