WDPN31 PGTW 060300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (NINETEEN) WARNING NR 04// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 19W (NINETEEN), LOCATED APPROXIMATELY 364 NM EAST-SOUTHEAST OF HONG KONG HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL SATELLITE IMAGERY DEPICTS A SYMMETRIC AREA OF DEEP CONVECTION BEING SHEARED TO THE WEST OF THE A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC). A 052251Z SSMIS 89 GHZ COLOR ENHANCED MICROWAVE IMAGE SHOWS SHALLOW BANDING INTO THE LLCC, WITH DEEP CONVECTIVE ACTIVITY LIMITED TO THE FAR WESTERN PERIPHERY, ABOUT 30 NM FROM THE LLCC. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC, RECENT SATELLITE FIX LOCATIONS AND ANALYSIS OF THE PREVIOUSLY MENTIONED MICROWAVE IMAGERY. THE INITIAL INTENSITY REMAINS AT 30 KNOTS, BASED ON RECENT MULTIAGENCY SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM PGTW OF 1.5 (25 KNOTS) AND IN LINE WITH A 0010Z AUTOMATED DVORAK TECHNIQUE (ADT) ESTIMATE OF 2.1 (33 KNOTS). ENVIRONMENTAL CONDITIONS HAVE IMPROVED SLIGHTLY SINCE THE PREVIOUS WARNINGS, WITH STRONG EQUATORWARD OUTFLOW AND DIFFLUENCE ALOFT, AND MODERATE (20-25 KTS) VERTICAL WIND SHEAR (VWS). SEA SURFACE TEMPERATURES (SSTS) REMAIN HIGH BETWEEN 28-29 DEG CELSIUS. TD 19W HAS SLOWED OVER THE PAST HOUR PRIOR TO ISSUANCE OF THIS WARNING, AS AN EXTENSION OF THE LOW- LEVEL RIDGE TO THE EAST NOSED IN TOWARDS THE NORTH OF THE SYSTEM. OVERALL, HOWEVER THE SYSTEM CONTINUES TO TRACK ALONG THE WESTERN PERIPHERY OF THE DEEP SUBTROPICAL RIDGE (STR) CENTERED FAR TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST TRACK PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 19W IS FORECAST TO CONTINUE TRACKING NORTH-NORTHWESTWARD THROUGHOUT THE FORECAST PERIOD, UNDER THE INFLUENCE OF THE LOW LEVEL FLOW ALONG THE WESTERN PERIPHERY OF A DEEP STR FAR TO THE NORTHEAST. THE SYSTEM WILL REMAIN WEAK AND SHALLOW AND SO BE PRIMARILY INFLUENCED BY THE LOW LEVEL (850MB AND BELOW) FLOW PATTERN, WHICH IS ORIENTED GENERALLY NORTH-SOUTH. THE SYSTEM IS FORECAST TO MAKE LANDFALL AS A WEAK TROPICAL DEPRESSION BETWEEN TAUS 36 AND 48, AND RAPIDLY DISSIPATE OVER SOUTHEASTERN CHINA. TD 19W IS NOT EXPECTED TO INTENSIFY THROUGH TAU 36, AS THE EQUATORWARD OUTFLOW WILL CONTINUE TO BE OFFSET BY MODERATE TO HIGH VWS AND DECREASING SSTS AS IT NEARS THE CHINESE COAST. MODEL GUIDANCE AGREEMENT HAS DECREASED SINCE THE LAST FORECAST, WITH SIGNIFICANT SPREAD NOW APPEARING IN THE MODEL TRACKERS. THE JAPANESE AND GFS ENSEMBLES ARE THE WESTERN OUTLIERS, WHILE THE ECMWF SOLUTIONS ARE THE EASTERN OUTLIERS, TAKING THE SYSTEM THROUGH THE TAIWAN STRAIT TO NEAR SHANGHAI. THE HWRF SOLUTION PICKS UP ON THE SLOWING FORWARD MOTION, BUT THEN MOVES THE SYSTEM DUE NORTH OVER TAIWAN. THE OFFICIAL TRACK LIES NEAR THE MULTI-MODEL CONSENSUS THROUGH TAU 36, THEN DEVIATES TO THE WEST THEREAFTER THROUGH DISSIPATION. DUE TO THE HIGH UNCERTAINTY IN THE MODEL SOLUTIONS, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN