WDPN33 PGTW 020300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 22W WARNING NR 20// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON 22W (NALGAE), LOCATED APPROXIMATELY 700 NM EAST- SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS CENTRAL CONVECTION REMAINS DEEP BUT BANDING HAS UNRAVELED AND BROKEN UP. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION WITH POOR CONFIDENCE. THE INITIAL INTENSITY WAS SUPPORTED BY SUBJECTIVE DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES TY 22W IS TO THE SOUTHWEST OF A RIDGE AXIS IN A DIFFLUENT ZONE WITH LIGHT (05-10 KT) VERTICAL WIND SHEAR (VWS). WATER VAPOR ANIMATION SHOWS GOOD POLEWARD BUT WEAK EQUATORWARD OUTFLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED AND HIGHLY ZONAL RIDGE TO THE NORTH. 3. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY. B. TY 22W IS EXPECTED TO REMAIN ON THE AFOREMENTIONED TRACK THROUGOUT THE DURATION OF THE FORECAST. A COOLER POOL OF WATER ALONG THE TRACK AFTER TAU 12 WILL SLIGHTLY WEAKEN THE SYSTEM BUT THE SYSTEM SHOULD REINTENSIFY AS SEA SURFACE TEMPERATURES RISE ANEW AFTER TAU 36. HOWEVER, AS THE CYCLONE ENTERS THE GULF OF TONKIN, VWS IS EXPECTED TO RISE CAUSING THE SYSTEM TO AGAIN GRADUALLY WEAKEN. C. AFTER TAU 72, TYPHOON NALGAE WILL MAKE LANDFALL OVER NORTH VIETNAM AND RAPIDLY DETERIORATE. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT EXCEPT FOR WBAR, WHICH TRACKS THE SYSTEM NORTHWESTWARD INTO THE STEERING RIDGE. THIS FORECAST IS MORE IN AGREEMENT WITH A STRONGER STEERING RIDGE AND IS SLIGHTLY SOUTH OF MODEL CONSENSUS AT THE END OF THE FORECAST PERIOD TO ACCOUNT FOR WBAR.// NNNN