MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 33W (TEMBIN) WARNING NR 17// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 33W (TEMBIN), LOCATED APPROXIMATELY 245 NM EAST- SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS FLARING DEEP CONVECTION WITH A DENSE OVERCAST CLOUD SHIELD OBSCURING THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH MODERATE CONFIDENCE BASED ON THE AFOREMENTIONED OBSCURED LLCC, WITH NO RECENT MICROWAVE IMAGERY AVAILABLE TO HELP LOCATE THE CENTER. THE MOST RECENT MICROWAVE IMAGE WAS A 241355Z AMSU-B 89GHZ IMAGE, WHICH REVEALED A VERY DISTINCT MICROWAVE EYE FEATURE WITH CONVECTIVE BANDING FORMING AN EYEWALL SURROUNDING A MICROWAVE EYE FEATURE. UPPER-LEVEL ANALYSIS INDICATES A WEAKLY SUPPORTIVE ENVIRONMENT CHARACTERIZED BY MODERATE (20 TO 25 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. THE RELATIVELY HIGH VWS IS NEARLY IN PHASE WITH THE SHEAR VECTOR, LEADING TO LOWER EFFECTIVE SHEAR. THE SYSTEM HAS RECENTLY MOVED OVER AN AREA OF LOWER SEA SURFACE TEMPERATURES (SSTS) NEAR 26 DEC CELSIUS, WHICH REMAIN ENTRENCHED WESTWARD TO THE VIETNAM COAST. THE INITIAL INTENSITY REMAINS ASSESSED AT 80 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T4.5 (77 KNOTS), A CIMSS 241140Z SATCON ESTIMATE OF 79 KNOTS, AND AN ADVANCED DVORAK TECHNIQUE (ADT) ESTIMATE OF T4.8 (84 KNOTS). TY 33W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF AN EAST- WEST ORIENTED SUBTROPICAL RIDGE CENTERED NEAR 20 DEG NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 33W WILL CONTINUE TO TRACK WESTWARD TO WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR THROUGH TAU 72. TY 33W HAS REACHED ITS PEAK INTENSITY AND WILL BEGIN TO RAPIDLY WEAKEN HEREAFTER, UNDER THE COMBINED INFLUENCE OF INCREASING VWS AND DECREASING SSTS. THE SYSTEM IS EXPECTED TO MAKE LANDFALL ALONG THE SOUTHERN COAST OF VIETNAM NEAR TAU 24, AND WILL UNDERGO ADDITIONAL WEAKENING AS IT INTERACTS WITH TERRAIN. DESPITE RE- EMERGING OVER THE GULF OF THAILAND BY TAU 36, THE SYSTEM IS EXPECTED TO CONTINUE WEAKENING AS VWS REMAINS HIGH. TY 33W WILL BEGIN DISSIPATING AS IT CROSSES THE MALAY PENINSULA NEAR TAU 60 AND IS EXPECTED TO DISSIPATE BY TAU 72 IN THE EASTERN BAY OF BENGAL. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 180NM SPREAD IN MODEL SOLUTIONS AT TAU 72 LEADING TO HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN