MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (TEMBIN) WARNING NR 12// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 15W (TEMBIN), LOCATED APPROXIMATELY 255 NM SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTH-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED OVERALL TIGHT CONSOLIDATION AND SYMMETRY EVEN AS POLEWARD OUTFLOW HAS SLIGHTLY DIMINISHED. THE INITIAL POSITION IS BASED ON FIXES FROM MULTIPLE AGENCIES. THE INITIAL INTENSITY IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES TY 15W HAS SUSTAINED A MESOSCALE ANTICYCLONE THAT CONTINUES TO PROVIDE GOOD OUTFLOW DESPITE TWO TUTT CELLS, ONE TO THE NORTH AND ONE TO THE SOUTHWEST OF THE CYCLONE, ARE CAUSING SUBSIDENCE AND STRONG SHEAR ALONG THE WEST TO SOUTHWESTERN FLANK. THE SYSTEM IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 15W IS FORECAST TO TRACK ON A MORE WESTWARD DIRECTION AS THE STR FIRMLY ASSUMES STEERING OF THE SYSTEM AFTER TAU 12. CONCURRENTLY, THE INTENSITIES WILL BEGIN TO DROP AS VERTICAL WIND SHEAR INCREASES. TY 15W WILL MAKE LANDFALL ALONG THE CENTRAL EASTERN COAST OF TAIWAN SHORTLY AFTER TAU 36, WEAKEN DUE TO TOPOGRAPHIC EFFECTS, CROSS THE TAIWAN STRAIT, AND MAKE A SECONDARY LANDFALL INTO CHINA BEFORE TAU 72. C. AFTER TAU 72, TYPHOON TEMBIN WILL RAPIDLY DECAY DUE TO TOPOGRAPHICAL EFFECTS, TRACK SOUTHWESTWARD WITH THE LOW LEVEL FLOW, AND DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND BY TAU 120. THE AVAILABLE NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT UP TO TAU 72 WITH TWO DISTINCT OUTLIERS - AFTER TAU 24, EGRR IS UNREALISTICALLY TRACKING THE VORTEX ABRUPTLY NORTHWARD INTO THE STEERING RIDGE; GFS MAKES A COUNTER-CLOCKWISE LOOP AFTER TAU 48, POSSIBLY INDICATING A BINARY INTERACTION WITH TYPHOON 16W, CURRENTLY LOCATED SOUTHWEST OF IWO TO, JAPAN. THERE IS HIGH CONFIDENCE IN THE TRACK FORECAST UP TO TAU 72, AFTER WHICH, THE CONFIDENCE IS LOW DUE TO THE UNCERTAINTY OF THE LONG RANGE SYNOPTIC PATTERN. // NNNN NNNN