WDPN32 PGTW 120300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 09W (NINE), LOCATED APPROXIMATELY 18 NM WEST- NORTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THAT THE DEEPEST CONVECTION LOCATED ALONG THE PERIPHERY OF THE SYSTEM HAS STARTED TO DISSIPATE, BUT A NEW CENTRAL CONVECTIVE MASS HAS DEVELOPED IN THE PAST FEW HOURS. RADAR IMAGERY FROM GUAM HAS SHOWS THE LOW LEVEL CIRCULATION CENTER HAS UNDERGONE INCREASED ORGANIZATIONAL IMPROVEMENTS OVER THE PAST SIX HOURS. THE CURRENT INTENSITY HAS BEEN MAINTAINED AT 30 KNOTS, BASED ON DVORAK ESTIMATES FROM PGTW, KNES AND RJTD HOLDING STEADY FROM THE PREVIOUS FORECAST. TD 09W CONTINUES TO TRACK ALONG THE SOUTHERN PERIPHERY OF A DEEP- LAYERED SUBTROPICAL RIDGE (STR), ANCHORED BETWEEN IWO TO AND GUAM. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST TRACK PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TD 09W IS FORECAST TO TRACK WESTWARD FOR THE NEXT 72 HOURS ALONG THE SOUTHERN PERIPHERY OF THE STR. BASED ON THE SHIFT IN UPPER LEVEL SUPPORT, THE OVERALL ENVIRONMENT WILL STRUGGLE TO ALIGN FOR THE NEXT 36 TO 48 HOURS, LEADING TO A SLOW DEVELOPMENT POTENTIAL THROUGH TAU 48. SEA SURFACE TEMPERATURES (SST) REMAIN FAVORABLE ALONG THE FORECASTED TRACK, BUT THE OUTFLOW WILL REMAIN THE LIMITING FACTOR IN THE NEAR TERM. BY TAU 72, VERTICAL WIND SHEAR IS EXPECTED TO DECREASE ALLOWING FOR INCREASED INTENSIFICATION. C. AFTER TAU 72, A MID-LATITUDE TROUGH IS FORECAST TO DIG OVER EASTERN CHINA, CAUSING A SHIFT IN THE STR, LEADING TO A MORE WEST- NORTHWEST TRACK TOWARDS THE NORTHERN PART OF LUZON. ADDITIONALLY, THE VERY FAVORABLE SST VALUES PRIOR TO THE APPROACH WILL LEAD TO A MAXIMUM INTENSITY AROUND TAU 108, POSSIBLY NEAR 100 KNOTS BUT IS NOT REFLECTED IN THE FORECAST AS THE TAU 120 INTENSITY OF 85 KNOTS ENCOMPASSES A SLIGHT IMPACT TO THE LOW LEVEL STRUCTURE AS THE INFLOW WITHIN THE NORTHWEST QUADRANT IS IMPACTED BY CROSSING OVER LUZON. THE AVAILABLE MODEL GUIDANCE IS IN GOOD AGREEMENT; HOWEVER, DUE TO THE INITIAL POSITIONING AND TRACK SPEED UNCERTAINTY, THE OVERALL CONFIDENCE IN THE FORECAST REMAINS LOW.// NNNN