WDPN33 PGTW 021500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W WARNING NR 22// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM 22W (NALGAE), LOCATED APPROXIMATELY 620 NM EAST-SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY SHOWS DEEP CENTRAL CONVECTIVE BAND WRAPPING FROM THE NORTH AND A 021021Z SSMIS MICROWAVE IMAGE DEPICTS A LARGE LOW LEVEL CONVECTIVE BAND LOOSELY WRAPPING AROUND THE WESTERN PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS BASED ON THE SSMIS IMAGE WITH FAIR CONFIDENCE DUE TO THE BROAD LLCC. THE INITIAL INTENSITY IS BASED ON THE PGTW, KNES, AND RJTD DVORAK ESTIMATES OF 45 TO 65 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN AN AREA OF MODERATE EASTERLY VERTICAL WIND SHEAR (VWS) AND WATER VAPOR IMAGERY SHOWS GOOD EQUATORWARD OUTFLOW AND IMPROVING POLEWARD OUTFLOW. 3. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY. B. TS 22W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP LAYER SUBTROPICAL STEERING RIDGE, WHICH IS EXPECTED TO REMAIN THE MAIN STEERING INFLUENCE THROUGHOUT THE FORECAST PERIOD. INTENSIFICATION WILL BE HINDERED BY THE MODERATE VWS AND A COOLER PATCH OF WATER, ALTHOUGH THE SYSTEM IS EXPECTED TO SLIGHTLY INTENSIFY ONCE IT MOVES BACK OVER WARMER WATER. BY TAU 48, TS 22W SHOULD TRACK JUST SOUTH OF HAINAN AND BEGIN TO WEAKEN DUE TO LAND INTERACTION. C. AFTER TAU 72, TS 22W WILL MAKE LANDFALL OVER VIETNAM AND DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE BY TAU 120. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT EXCEPT FOR WBAR, WHICH TRACKS THE SYSTEM NORTHWESTWARD INTO THE STEERING RIDGE. ADDITIONALLY, GFS DISSIPATES THE SYSTEM OVER HAINAN. THIS FORECAST FAVORS A STRONGER STEERING RIDGE TO THE NORTH AND IS SLIGHTLY SOUTH OF MODEL CONSENSUS TO ACCOUNT FOR WBAR AND GFS ERRORS. THIS FORECAST INTENSITY IS LOWER THAN THE PREVIOUS FORECASTS BECAUSE THE SYSTEM HAS WEAKENED MORE THAN PREVIOUSLY EXPECTED AFTER CROSSING OVER LUZON.// NNNN