WDPN31 PGTW 290300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (NOCK-TEN)// WARNING NR 18// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM 10W (NOCK-TEN), LOCATED APPROXIMATELY 250 NM SOUTH-SOUTHWEST OF HONG KONG, CHINA, HAS TRACKED WEST-NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. RECENT MULTISPECTRAL SATELLITE IMAGERY SHOWS THAT DEEP CENTRAL CONVECTION HAS PERSISTED OVER THE LOW LEVEL CIRCULATION CENTER (LLCC) BUT CONTINUES TO BE SLIGHTLY DISPLACED TO THE SOUTH. ADDITIONALLY, A CURVILINEAR BAND HAS FORMED TO THE SOUTH OF THE LLCC WHICH WRAPS INTO THE EASTERN HALF OF THE STORM. A 28/2201Z 91 GHZ SSMIS IMAGE DEPICTS THE VIGOROUS DEEP CONVECTION ASSOCIATED WITH THE SOUTHERN FEEDER BAND, LACK OF DEEP CONVECTION IN THE NORTHERN SEMICIRCLE, AND DISPLAYS THE CONVECTIVE ELEMENTS THAT ARE BEGINNING TO FORM OVER SOUTHERN CHINA AS THE OUTER PERIPHERY OF TS 10W BEGINS TO INTERACT WITH LAND. RECENT UPPER LEVEL ANALYSIS AND ANIMATED WATER VAPOR IMAGERY INDICATE THAT TS 10W IS IN AN AREA OF MODERATE NORTHEASTERLY VERTICAL WIND SHEAR AS A MID- TO UPPER-LEVEL SUBTROPICAL ANTICYCLONE CONTINUES TO BUILD OVER SOUTHERN CHINA. DESPITE THE MODERATE VERTICAL WINDSHEAR TO THE NORTH, THE UPPER LEVEL DIVERGENCE REMAINS FAVORABLE WITH DISTINCTIVE CROSS EQUATORIAL OUTFLOW AND A CONTINUED POLEWARD OUTFLOW CHANNEL INTO A TROPICAL UPPER TROPOSPHERIC TROUGH CELL TO THE NORTHEAST. THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM THE AFOREMENTIONED MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS BASED ON A DVORAK ESTIMATE OF 55 KNOTS FROM KNES. TS 10W CONTINUES TO BE STEERED BY THE MID- TO UPPER-LEVEL SUBTROPICAL RIDGE CENTERED OVER SOUTHERN ASIA. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY. B. TS 10W WILL CONTINUE TO TRACK WESTWARD AS THE UPPER LEVEL STEERING RIDGE MAINTAINS ITS INFLUENCE ON THE STORM MOTION. AFTER TAU 12 THE LLCC WILL BE OVER HAINAN ISLAND AND TOPOGRAPHICAL EFFECTS WILL CAUSE A SLIGHT WEAKENING. AFTER TAU 24 TS 10W WILL HAVE RE- EMERGED OVER THE EXTREMELY WARM (30 DEGREES CELSIUS AND GREATER) WATERS OF THE GULF OF TONKIN WHERE THE STORM WILL RE-INTENSIFY BEFORE MAKING LANDFALL FOR THE FINAL TIME AFTER TAU 36. BY TAU 48 THE SYSTEM WILL HAVE BEGUN TO DISSIPATE. C. AFTER TAU 72, TS 10W WILL DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE JUST NORTH OF VIENTIANE, LAOS. THIS TRACK FORECAST IS SOUTH OF CONSENSUS DUE TO THE ANALYSIS OF SOUNDINGS OVER SOUTHERN ASIA WHICH REINFORCE THE POSITION, AND THEREFORE THE FORECAST STEERING PHILOSOPHY, OF THE UPPER-LEVEL SUBTROPICAL RIDGE. SUBSEQUENTLY, THIS FORECAST IS ALSO FASTER THAN CONSENSUS DUE TO THE MORE SOUTHERLY TRACK OVER HAINAN ISLAND.// NNNN