WDPN31 PGTW 220900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 13W (THIRTEEN), LOCATED APPROXIMATELY 239 NM SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHEASTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS POCKETS OF DEEP CONVECTION REMAIN BUT THE OVERALL STORM STRUCTURE HAS CONTINUED TO DETERIORATE. THE LOW LEVEL CIRCULATION CENTER (LLCC) IS BECOMING DISORGANIZED AND DIFFICULT TO LOCATE. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE AND IS BASED ON A 220641Z 36GHZ GMI MICROWAVE IMAGE WHICH SHOWS EVIDENCE OF WEAK LOW LEVEL BANDING. THE INITIAL INTENSITY OF 30 KNOTS IS BASED ON A DVORAK CURRENT INTENSITY (CI) ESTIMATE OF T2.0 (30 KNOTS) FROM PGTW. ENVIRONMENTAL ANALYSIS SHOWS THAT TD 13W HAS VERY WEAK POLEWARD AND EQUATORWARD OUTFLOW CHANNELS. HOWEVER, VERTICAL WIND SHEAR REMAINS FAVORABLE, BETWEEN 10 AND 15 KNOTS. SEA SURFACE TEMPERATURES REMAIN FAVORABLE, RANGING BETWEEN 29 TO 30 DEGREES CELSIUS. TD 13W IS TRACKING GENERALLY NORTHWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 13W WILL CONTINUE TO TRACK GENERALLY NORTHWARD WHILE UNDER THE INFLUENCE OF THE STR TO THE NORTHEAST. UPPER LEVEL OUTFLOW SUPPORT WILL CONTINUE TO DIMINISH AS THE LOW LEVEL STRUCTURE ALSO BECOMES INCREASINGLY DISORGANIZED. TD 13W WILL MAINTAIN AN INTENSITY OF 30 KNOTS THROUGH TAU 24. AFTER TAU 24 TD 13W WILL TRACK NORTH-NORTHWESTWARD AROUND THE STR. DYNAMIC MODEL GUIDANCE FORECASTS A DECREASE IN INTENSITY AFTER TAU 24 AND THAT TD 13W MAY DISSIPATE JUST PRIOR TO MAKING LANDFALL. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT WITH GENERALLY LESS THAN A 100NM SPREAD. THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. THE JTWC FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS.// NNNN