WDPN31 PGTW 060300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTY-TWO) WARNING NR 03// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 22W (TWENTY-TWO), LOCATED APPROXIMATELY 341 NM EAST-SOUTHEAST OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 19 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE LOW LEVEL CIRCULATION HAS BECOME PARTIALLY EXPOSED AS THE SYSTEM REMAINS DISORGANIZED. THE INITIAL POSITION IS EXTRAPOLATED FROM THE MSI LOOP AND LINED UP WITH A LOW REFLECTIVITY CIRCULATION FEATURE IN THE 052301Z 91GHZ SSSMI-S MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY of 25 KNOTS IS BASED ON THE DVORAK ESTIMATE FROM PGTW. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LIGHT TO MODERATE (10-15 KNOT) VERTICAL WIND SHEAR (VWS) WITH MINIMAL SOUTHEASTWARD OUTFLOW. A TUTT CELL TO THE NORTHEAST IS CAUSING SUBSIDENCE ALONG THE NORTHERN PERIPHERIES AND SUPPRESSING CONVECTION, AS EVIDENT ON ANIMATED WATER VAPOR SATELLITE IMAGERY. SEA SURFACE TEMPERATURES, HOWEVER, ARE FAVORABLY WARM AT 30C. OVERALL, THE ENVIRONMENT IS MARGINALLY FAVORABLE FOR DEVELOPMENT. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE TO THE NORTH (STR). 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 22W WILL CONTINUE TO TRACK GENERALLY WESTWARD OVER THE NEXT 72 HOURS TOWARDS THE SOUTH CHINA SEA. THE ENVIRONMENT WILL REMAIN MARGINALLY FAVORABLE RESULTING IN WEAK INTENSIFICATION, PEAKING AT 45 KNOTS NEAR TAU 48. C. BEYOND TAU 72, A SECONDARY STR BUILDING OVER EASTERN CHINA WILL ASSUME STEERING AND CAUSE TD 22W TO TRACK SOUTHWESTWARD. THIS WILL, HOWEVER, INCREASE VWS AND UPPER-LEVEL SUBSIDENCE ALONG THE NORTHWEST PERIPHERY RESULTING IN GRADUAL DECAY. BY END OF FORECAST, TD 22W WILL BE REDUCED BACK TO 25 KNOTS AS IT BEGINS TO DISSIPATE NEAR HAINAN. THE AVAILABLE NUMERIC MODELS ARE WIDELY SPREAD ESPECIALLY AFTER TAU 12, LENDING LOW CONFIDENCE TO THE JTWC TRACK FORECAST.//