MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (MEGI) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 20W (MEGI), LOCATED APPROXIMATELY 582 NM EAST- SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND RECENT MICROWAVE IMAGERY DEPICT A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH MULTIPLE TIGHTLY-CURVED CONVECTIVE BANDS WRAPPING INTO A WELL-DEFINED CENTER. TY 20W HAS NOT YET FORMED AN EYE BUT HAS BECOME BETTER ORGANIZED DUE TO THE EXCELLENT ENVIRONMENTAL CONDITIONS. OVERALL, THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION BASED ON THE MSI AND A 250657Z SSMIS 37GHZ IMAGE, WHICH SHOWS A MICROWAVE EYE FEATURE. THE INITIAL INTENSITY OF 95 KNOTS IS HEDGED SLIGHTLY HIGHER THAN THE DVORAK INTENSITY ESTIMATES OF T5.0 (90 KNOTS) BASED ON THE IMPROVING CONVECTIVE STRUCTURE. UPPER-LEVEL ANALYSIS CONTINUES TO SHOW EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW ASSOCIATED WITH A TUTT CELL POSITIONED TO THE EAST. TY MEGI IS TRACKING WEST- NORTHWESTWARD ALONG THE PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. THE 34-KNOT WIND RADII HAVE BEEN INCREASED SIGNIFICANTLY BASED ON ANALYSIS OF A RECENT ASCAT IMAGE, AND REFLECTS AN EXPANSIVE GALE-FORCE WIND AREA OVER ALL QUADRANTS EXCEPT THE SOUTHWEST QUADRANT. B. TY 20W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD IN A STRAIGHT-RUNNER PATTERN WHILE INTENSIFYING TO A PEAK OF 110 KNOTS UNDER VERY FAVORABLE CONDITIONS. THE STR IS EXPECTED TO REMAIN STRONG AND EAST-WEST ORIENTED THROUGH THE FORECAST PERIOD. AS A RESULT, THE DYNAMIC GUIDANCE IS IN EXCELLENT AGREEMENT WITH A 100-NM SPREAD IN SOLUTIONS AT TAU 48, NEAR LANDFALL OVER SOUTHERN TAIWAN. AFTER TAU 48, TY MEGI WILL CROSS OVER SOUTHERN TAIWAN AND WEAKEN SIGNIFICANTLY DUE TO LAND INTERACTION. C. AFTER RE-EMERGING OVER THE TAIWAN STRAIT, THE SYSTEM WILL MAKE LANDFALL AGAIN OVER SOUTHEAST CHINA NEAR TAU 72, AND WILL BEGIN DISSIPATING AS IT TRACKS FURTHER INLAND. DUE TO THE TIGHT MODEL AGREEMENT IN THE EXTENDED TAUS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS AND IS HIGHLY CONSISTENT WITH PREVIOUS JTWC FORECASTS.// NNNN NNNN