WDPN31 PGTW 050900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (GONI) WARNING NR 034// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 22W (GONI), LOCATED APPROXIMATELY 216 NM EAST-SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WEST-SOUTHWESTWARD AT 04 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS A BROAD, FULLY-EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE ASSOCIATED DEEP CONVECTION SHEARED TO THE NORTHWEST. DUE TO THE FULLY-EXPOSED NATURE AND A TIMELY 050540Z AMSR2 89 GHZ MICROWAVE IMAGE DEPICTING BANDING WRAPPING INTO THE LLCC, THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY IS SET AT 35 KTS BASED ON A 050609Z SATELLITE CONSENSUS ESTIMATE OF 37 KTS AND DVORAK CURRENT INTENSITY ESTIMATES OF T2.0-2.5 (30-35 KTS) BY PGTW AND RJTD. FURTHERMORE, A 050240Z ASCAT-C IMAGE SHOWS A BROAD SWATH OF 30-34 KT WINDS OVER THE WESTERN SEMICIRCLE. ALL WIND RADII HAVE BEEN UPDATED BASED ON THE AFOREMENTIONED ASCAT IMAGE. TS 22W IS TRACKING THROUGH A MARGINAL ENVIRONMENT CONSISTING OF MODERATE (15-20 KT) VERTICAL WIND SHEAR (VWS) OFFSET BY DIVERGENT FLOW ALOFT AND WARM (26-27 CELSIUS) SEA SURFACE TEMPERATURES (SST). TS 22W IS TRACKING WEST-SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 22W WILL CONTINUE TO TRACK GENERALLY WESTWARD FOR THE DURATION OF THE FORECAST PERIOD UNDER THE INFLUENCE OF THE AFOREMENTIONED STR. DUE TO PERSISTENT MODERATE VWS, THE SYSTEM SHOULD STEADILY WEAKEN AS IT APPROACHES THE COAST, MAKING LANDFALL IN CENTRAL VIETNAM AROUND TAU 18. AFTERWARDS, INTERACTION WITH THE RUGGED TERRAIN WILL CONTINUE TO WEAKEN THE SYSTEM, LEADING TO DISSIPATION OVER LAND BY TAU 36. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT SHOWING A 76 NM SPREAD IN THE SOLUTIONS AT LANDFALL AND THEN INCREASING TO 126 NM BY TAU 36 AS THE SYSTEM TRACKS INLAND. THIS INCREASING SPREAD PLACES FAIR CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS POSITIONED JUST SOUTH OF THE MULTI-MODEL CONSENSUS.// NNNN