MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEKKHALA) WARNING NR 004// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 07W (MEKKHALA), LOCATED APPROXIMATELY 332 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTIVE BANDING OVER THE SOUTHERN SEMICIRCLE WRAPPING INTO THE CENTER. THE CURRENT POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN THE MSI LOOP AND THE LOW LEVEL CIRCULATION FEATURE PRESENT IN A 100535Z AMSR2 89GHZ IMAGE. THE INTENSITY OF 35 KNOTS IS PLACED WITH HIGH CONFIDENCE AND IS BASED ON MULTIAGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T2.0 (30 KTS, RJTD) AND T2.5 (35 KTS, PGTW), A 100610Z ADVANCED DVORAK TECHNIQUE CURRENT INTENSITY ESTIMATE OF T2.4 (34 KTS) AND A 100610Z SATCON ESTIMATE OF 36 KTS. TS MEKKHALA IS TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE (STR) EXTENSION. THE SYSTEM IS SITUATED IN AN AREA OF HIGH (25-30 KTS) VERTICAL WIND SHEAR AND VERY WARM (29-30C) SEA SURFACE TEMPERATURES. UPPER-LEVEL DIFFLUENCE IS LIMITED, BUT AN ANALYSIS OF SATELLITE-DERIVED ATMOSPHERIC MOTION VECTORS SUGGESTS THAT EQUATORWARD OUTFLOW ALOFT CONTINUES TO STRENGTHEN. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 07W WILL CONTINUE TO TRACK POLEWARD ALONG THE STR THROUGH THE ENTIRE 48 HOUR FORECAST PERIOD. THE SYSTEM WILL CONTINUE TO STEADILY INTENSIFY TO 45 KTS BY TAU 12 DESPITE THE PERSISTENT HIGH VWS, LARGELY DUE TO CONTINUED PASSAGE OVER VERY WARM WATER AND INCREASING POLEWARD OUTFLOW AIDED BY AN UPPER-LEVEL TROUGH POSITIONED TO THE NORTHEAST. TS MEKKHALA IS EXPECTED TO MAKE LANDFALL IN SOUTHEASTERN CHINA JUST PRIOR TO TAU 48. AFTER THE SYSTEM MAKES LANDFALL IT WILL BEGIN TO WEAKEN DUE TO THE FRICTIONAL EFFECTS OF LAND AND FULLY DISSIPATE OVER LAND BY TAU 48. NUMERICAL MODEL SOLUTIONS ARE IN FAIR AGREEMENT REGARDING THE OVERALL FORECAST SCENARIO, BUT THERE IS SOME SPREAD IN THE EXACT POSITION OF LANDFALL WITH A 60NM CROSS TRACK SPREAD IN SOLUTIONS AT TAU 48. OVERALL, MODEL SOLUTIONS LEND FAIR CONFIDENCE IN JTWC TRACK FORECAST.// NNNN NNNN