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 24W, LOCATED APPROXIMATELY 520 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS SEVERAL DEEP CONVECTIVE BANDS ARE BUILDING TOWARDS A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC). A RECENT 231542Z OSCAT PASS INDICATES A SLIGHT ELONGATION OF THE LLCC ALONG THE EAST-WEST AXIS WITH A MAJORITY OF THE WINDS NEAR THE CENTER BEING RAIN FLAGGED. HOWEVER, STRONGER WINDS ALONG THE OUTER PERIPHERY OF THE SYSTEM SUPPORT THE CURRENT INTENSITY OF 30 KNOTS. DVORAK INTENSITY ESTIMATES FROM PGTW, KNES, AND RJTD RANGE FROM 25 TO 35 KNOTS BUT ARE CONSISTENT WITH THE CURRENT INTENSITY. UPPER LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE IS LOCATED OVER THE LLCC AND IS PROVIDING FAVORABLE RADIAL OUTFLOW AND CREATING A LOW VERTICAL WIND SHEAR ENVIRONMENT. A MID-LATITUDE TROUGH TO THE NORTH AND A TROPICAL UPPER TROPOSPHERIC TROUGH TO THE EAST HAVE BEEN AMPLIFYING THE POLEWARD AND EASTWARD PORTIONS OF THE RADIAL OUTFLOW. TD 24W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTH OF THE SYSTEM. 3. FORECAST REASONING A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST PHILOSOPHY. B. TD 24W IS EXPECTED TO TRACK ALONG THE SOUTHERN PERIPHERY OF THE STR ACROSS THE CENTRAL PORTION OF THE PHILIPPINES INTO THE SOUTH CHINA SEA (SCS) THROUGH TAU 72. WEAK INTENSIFICATION IS EXPECTED OVER THE NEXT 12 HOURS PRIOR TO TRACKING OVER THE ISLANDS OF CENTRAL PHILIPPINES. THIS LAND INTERACTION WILL LIKELY INHIBIT FURTHER DEVELOPMENT UNTIL TD 24W MOVES OVER THE EASTERN EXTENT OF THE SCS WHERE THE LLCC WILL PICK UP ADDITIONAL WARM MOISTURE INFLOW FROM THE SULU SEA AND SCS. ONCE THE SYSTEM MOVES BACK OVER THE SCS, THE LLCC WILL BEGIN TO REORGANIZE, ALLOWING A STEADY INTENSIFICATION THROUGH TAU 72. ONE LIMITING FACTOR TO RAPID INTENSIFICATION WILL BE THE NORTHEASTERN COLD DRY AIR CURRENTLY PUSHING INTO THE SCS. THIS AIR MASS WILL HINDER THE AVAILABILITY OF A TROPICAL AIR MASS ALONG THE WESTERN HALF OF THE SYSTEM. C. AFTER TAU 72, TD 24W WILL CONTINUE TRACKING TOWARD THE NORTHERN COAST OF VIETNAM UNDER THE STEERING INFLUENCE OF THE STR. INTENSITY WILL CONTINUE TO BUILD IN A FAVORABLE ENVIRONMENT, BUT IS EXPECTED TO SLIGHTLY WEAKEN AS IT MOVES OVER THE COAST OF VIETNAM AROUND TAU 120. MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE CURRENT FORECAST TRACK, WITH THE FORECAST INTENSIFICATION SLIGHTLY BELOW GUIDANCE BASED ON THE EFFECTS OF CROSSING THE PHILIPPINES EARLY IN THE WARNING AND THE EFFECTS OF THE NORTHEAST SURGE IN THE MID TO LATE TAUS. THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK BASED ON TIGHT GROUPING OF AVAILABLE MODEL GUIDANCE.// NNNN NNNN