MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 24W WARNING NR 01// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 24W (TWENTY-FOUR), LOCATED APPROXIMATELY 575 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMI-CIRCLE WRAPPING INTO THE EAST QUADRANT OF THE LLCC. A 081558Z TRMM 37GHZ IMAGE DEPICTS A WELL-DEFINED LLCC WITH DEEP CONVECTIVE BANDING OVER THE WESTERN SEMI-CIRCLE WRAPPING INTO THE SOUTHEAST QUADRANT WITH DEFINED SHALLOW BANDING ELSEWHERE. BASED ON THE TRMM IMAGE AND A 081828Z NOAA-18 89GHZ IMAGE, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT WITH DIFFLUENT EASTERLY FLOW AND WEAK VERTICAL WIND SHEAR (VWS). THE INITIAL INTENSITY IS ASSESSED AT 25 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF 25 KNOTS FROM ALL AGENCIES. TD 24W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY. B. TD 24W IS FORECAST TO TRACK WESTWARD THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR. WITH THE EXCEPTION OF HWRF, THE DYNAMIC MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON A GENERALLY WESTWARD TRACK ACROSS LUZON. HWRF IS THE SOLE OUTLIER AND INDICATES AN EASTWARD TRACK AFTER TAU 36, WHICH IS DEEMED UNLIKELY DUE TO THE STRENGTH AND POSITION OF THE STR. TD 24W IS EXPECTED TO INTENSIFY SLOWLY THROUGH TAU 24 DUE TO PERSISTENT EASTERLY VWS. THEREAFTER, UPPER-LEVEL OUTFLOW WILL IMPROVE AND THE SYSTEM WILL RAPIDLY INTENSIFY TO A PEAK INTENSITY OF 70 KNOTS. C. IN THE EXTENDED PERIOD, TD 24W WILL TRACK ACROSS THE MOUNTAINOUS TERRAIN OF CENTRAL LUZON AND WILL SIGNIFICANTLY WEAKEN UNTIL IT TRACKS OVER THE SOUTH CHINA SEA. TD 24W WILL RE-INTENSIFY AS POLEWARD OUTFLOW IMPROVES TO AN INTENSITY OF 65 KNOTS BY TAU 120. TD 24W SHOULD TURN ONTO A WESTWARD TO WEST-SOUTHWESTWARD TRACK AS IT TRACKS UNDER THE WESTERN BRANCH OF THE STR. BASED ON THE TIGHT AGREEMENT OF DYNAMIC MODELS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED SLIGHTLY FASTER THAN THE MULTI- MODEL CONSENSUS.// NNNN NNNN