MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 20W (TWENTYTWO) WARNING NR 02// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION 22W (TWENTYTWO), LOCATED APPROXIMATELY 255 NM SOUTH-SOUTHWEST OF HONG KONG, HAS TRACKED WESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH FLARING CENTRAL CONVECTION BEING SHEARED TO THE SOUTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC AND A LOW REFLECTIVITY FEATURE OBSERVED IN A 232311Z 91GHZ SSMIS IMAGE. MULTI-AGENCY DVORAK ESTIMATES RANGE FROM T1.5 TO T2.0 (25 TO 30 KNOTS) AND LOCAL SHIP OBSERVATIONS ARE REPORTING WINDS IN EXCESS OF 25 KNOTS, WHICH IS THE BASIS FOR THE INITIAL 30 KNOT INTENSITY. UPPER-LEVEL ANALYSIS INDICATES FAIRLY STRONG EASTERLY FLOW FROM A WELL ESTABLISHED NORTHERN RIDGE. WHILE THE SYSTEM IS TRAVELING IN PHASE WITH THE UPPER-LEVEL WINDS, TD 22W HAS SLOWED DOWN OVER THE LAST SIX HOURS RESULTING IN A NOTABLE INCREASE IN WIND SHEAR. SSTS IN THE REGION ARE ALSO FAVORABLE NEAR 30 CELSIUS. CURRENTLY TD 20W IS TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHERN BOUNDARY OF A MID-TO-LOW LEVEL SUBTROPICAL RIDGE ANCHORED OVER TAIWAN. 3. FORECAST REASONING. A. TD 22W HAS SLOWED DOWN TO CONSIDERABLY IN THE LAST SIX HOURS RESULTING IN A DETERIORATING UPPER-LEVEL ENVIRONMENT, AS A RESULT FURTHER INTENSIFICATION IS UNLIKELY. B. TD 20W WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD OVER THE NEXT 48 HOURS AS THE SUBTROPICAL RIDGE BUILDS EXTENDING WESTWARD OVER CHINA. MODERATE TO HIGH VERTICAL WIND SHEAR WILL PERSIST FOR THE NEXT 24 HOURS HINDERING FURTHER CONSOLIDATION OF THE SYSTEM TO CONSOLIDATE AS IT TRAVERSES OVER THE WARM WATERS OF THE SOUTH CHINA SEA. TD 20W IS EXPECTED TO MAINTAIN INTENSITY AT 30 KNOTS FOR THE NEXT 12 HOURS BEFORE MAKING LANDFALL OVER HAINAN, AND REEMERGING OVER THE GULF OF TONKIN BY TAU 24. LAND INTERACTION WITH HAINAN WILL BEGIN TO WEAKEN THE SYSTEM BEFORE MAKING LANDFALL AGAIN OVER NORTHERN VIETNAM. THE SYSTEM WILL CONTINUE TO TRACK INLAND DISSIPATING BY TAU 48. DYNAMIC MODEL GUIDANCE SHOWS FAIRLY GOOD AGREEMENT, LENDING HIGH CONFIDENCE IN THE FORECAST TRACK.// NNNN NNNN