WDPN31 PGTW 280300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TRAMI) WARNING NR 031// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.7N 107.9E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 29 NM SOUTHWEST OF DA NANG, VIETNAM MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 04 KTS SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL DEPRESSION 22W (TRAMI) AFTER IT MADE A U-TURN AND IS TRACKING BACK SLOWLY TOWARDS COASTAL VIETNAM AND THE SOUTH CHINA NEAR THE CITY OF DA NANG. THE INITIAL POSITION IS THEREFORE PLACED WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH LOW CONFIDENCE BASED ON LACK OF DEVELOPING CONVECTION, WHILE THE SYSTEM TRANSITS OVER LAND, OFFSET BY REMAINING STRUCTURAL INTEGRITY OF THE CIRCULATION. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: COMPETING STEERING INFLUENCE OF SUBTROPICAL RIDGES TO THE WEST AND TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: NO CURRENT ESTIMATE RJTD: T2.5 - 35 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 5-10 KTS SST: OVER LAND OUTFLOW: WEAK EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: LOW INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: DESPITE THE LACK OF WARM WATER AND FRICTIONAL EFFECTS OF LAND INTERACTION, TROPICAL DEPRESSION 22W MANAGED TO MAINTAIN AN ORGANIZED CIRCULATION, WITH THE HELP OF VERY LOW VERTICAL WIND SHEAR (VWS). THE SYSTEM INTENSITY IS CURRENTLY ASSESSED TO BE AT 30 KTS, HOWEVER AS SOON AS IT MOVES OVER WATER WITHIN THE NEXT 24 HOURS, IT WILL ENCOUNTER AN INCREASINGLY STRONGER VWS FROM THE WEST AND SOUTHWEST. GIVEN THE MARGINALLY UNFAVORABLE CONDITIONS, TD 22W IS EXPECTED TO BEGIN WEAKENING SHORTLY AFTER AND COMPLETE DISSIPATION BY THE END OF THE FORECAST PERIOD. MODEL DISCUSSION: MODEL GUIDANCE IS INCONSISTENT IN TERMS OF BOTH TRACK AND DISSIPATION TIMELINE, WITH SOME MODELS (ECMWF ENSEMBLE) MOVING THE SYSTEM NORTH, RIGHT AFTER ER-EMERGING OVER WATER, WHILE OTHERS (GFS) PREDICTING A SOUTHWESTWARD TRACK. THERE IS A SIGNIFICANT DIFFERENCE IN VERTICAL WIND SHEAR VALUES BETWEEN THOSE TWO APPROACHES. ADDITIONALLY, SEA SURFACE TEMPERATURES ARE ALSO 2-3 DEGREES CELSIUS COLDER CLOSER TO HAINAN, THAN THEY ARE, IF THE SYSTEM WERE TO TRACK SOUTHWESTWARD. THEREFORE, BOTH TRACK AND INTENSITY ARE ASSESSED WITH LOW CONFIDENCE, WITH THE TRACK PLACED CLOSE TO THE MULTI-MODEL CONSENSUS, WITHOUT THE OUTLIERS, AND THE INTENSITY GUIDANCE SLIGHTLY LOWER THAN THE CONSENSUS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: LOW// NNNN