MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W (TWENTYFOUR) WARNING NR 01// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 24W (TWENTYFOUR), LOCATED APPROXIMATELY 262NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTIVE BANDING WRAPPING INTO THE LLCC. A 120745Z SSMIS 91GHZ IMAGE SHOWS IMPROVED DEEP CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. RECENT SCATTEROMETER IMAGERY INDICATES 25 TO 35 KNOT EASTERLY WINDS OVER THE NORTHERN SEMI-CIRCLE AND 20 TO 25 KNOT WINDS OVER THE SOUTHERN SEMI-CIRCLE. UPPER-LEVEL ANALYSIS DEPICTS A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR, EXCELLENT POLEWARD OUTFLOW (ENHANCED BY THE TUTT POSITIONED TO THE EAST), WARM SST (29-30C), AND HIGH OCEAN HEAT CONTENT VALUES. THE INITIAL INTENSITY IS ASSESSED AT 30 KNOTS BASED ON DVORAK ESTIMATES OF T2.0 (30 KNOTS) FROM PGTW AND KNES. TD 24W IS UNDER THE STEERING INFLUENCE OF THE EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH. 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY. B. TD 24W WILL TRACK WESTWARD AS IT REMAINS ON THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED STR. TD 24W WILL REMAIN A BROAD CIRCULATION AS IT TRANSITS OVER LUZON. UPON ENTERING THE SOUTH CHINA SEA AFTER TAU 18 THE STORM WILL INTENSIFY AND CONSOLIDATE. BY TAU 24 THE INTENSITY WILL INCREASE TO 40 KNOTS AS THE SYSTEM MOVES FARTHER FROM LUZON AND OUT OVER WARM OCEAN WATER WITH SSTS OF 29-30 CELSIUS. BY TAU 48 A SLIGHT WEAKENING IN THE STR WILL ALLOW FOR TD 24W TO TRACK WEST-NORTHWESTWARD WHILE INCREASING TO A PEAK INTENSITY OF 75 KNOTS AT TAU 72. C. IN THE EXTENDED PERIOD, TD 24W WILL CONTINUE TO TRACK WESTWARD AND WILL MAKE LANDFALL IN SOUTHERN HAINAN ISLAND NEAR TAU 78, WHICH WILL LEAD TO A SLIGHT WEAKENING TREND. TD 24W WILL MAKE LANDFALL AGAIN IN NORTHERN VIETNAM AFTER TAU 96 AND WILL WEAKEN RAPIDLY AS IT MOVES INLAND. OVERALL, DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN