WDPN31 PGTW 262100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (TRAMI) WARNING NR 026// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.0N 109.8E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 105 NM NORTHEAST OF DA NANG, VIETNAM MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 32 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A HEAVILY SHEARED TROPICAL STORM 22W, AS IT APPROACHES THE COAST OF VIETNAM. NEARLY 30 KTS OF VERTICAL WIND SHEAR, COMBINED WITH LAND INTERACTION IS LEADING TO STEADILY WEAKENING WIND FIELD STRUCTURE AND INTENSITY. AT THE SAME TIME, DEEP CONVECTION IS STILL PERSISTENT, PARTICULARLY OVER THE WESTERN PORTION OF THE SYSTEM, ENHANCED BY A MODERATE WESTWARD OUTFLOW. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON ANIMATED INFRARED IMAGERY. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON 261618Z OSCAT PASS, AS WELL AS OBJECTIVE AND AGENCY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS RJTD: T3.5 - 55 KTS KNES: T3.5 - 55 KTS DEMS: T4.0 - 65 KTS CIMSS SATCON: 58 KTS AT 261630Z CIMSS ADT: 43 KTS AT 261800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 25-30 KTS SST: 27-28 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: LOW INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 22W IS FORECAST TO CONTINUE TRACKING TOWARDS THE VIETNAM COAST, PARTICULARLY THE AREA NEAR THE CITY OF DA NANG, WHILE BEING STEERED BY A WEAKENING STR TO THE NORTH. AS TS 22W CLOSES ON THE COASTLINE, THE STEERING WILL TRANSITION INTO ANOTHER STR, LOCATED TO THE WEST OF THE SYSTEM, WHICH WILL EFFECTIVELY BLOCK ANY FURTHER WESTWARD PROPAGATION. MAJORITY OF THE MODEL GUIDANCE SUGGESTS THAT THE SYSTEM WILL THEN RE-CURVE OVER THE SOUTH CHINA SEA. INTENSE VERTICAL WIND SHEAR, LOWERING SEA SURFACE TEMPERATURES, AS WELL AS LAND INTERACTION WILL CAUSE TS 22W TO STEADILY WEAKEN THROUGHOUT THE FORECAST PERIOD. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT ONLY THROUGH THE INITIAL 12 HOURS, AS THE SYSTEM HEADS TOWARDS THE COAST. FURTHER OUT, UNCERTAINTY IS INCREASING, PARTICULARLY IN REGARD TO THE TRACK OF THE SYSTEM, WHICH ALMOST EVERY MODEL PAINTS A DIFFERENT PICTURE FOR, WITH SOME, LIKE GFS OR NAVGEM, TAKING THE SYSTEM DEEPER INLAND, WHILE OTHERS ONLY GRAZING THE COAST AND RE-EMERGING OVER WATER. INTENSITY GUIDANCE IS MORE CONSISTENT, WITH NEARLY ALL MODELS PREDICTING STEADY WEAKENING, WITH POTENTIAL FOR DISSIPATION TOWARDS THE END OF THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN