MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 27W (TWENTYSEVEN) WARNING NR 14// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 27W (TWENTYSEVEN), LOCATED APPROXIMATELY 313 NM SOUTH-SOUTHEAST OF ANDERSEN AFB, GUAM, HAS TRACKED WEST- NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD, PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH EXTENSIVE DEEP CONVECTION PERSISTING OVER THE SOUTHERN SEMI-CIRCLE OF THE LLCC ASSOCIATED WITH CONVERGENT WESTERLY FLOW. A 222053Z SSMIS 37GHZ IMAGE SHOWS BROAD BANDING WRAPPING INTO A WEAKLY-DEFINED LLCC, HOWEVER, A 222357Z ASCAT IMAGE SHOWS AN ELONGATED CIRCULATION WITH 25 TO 30 KNOT WINDS AROUND THE PERIPHERY WHILE A 222314Z OSCAT BULLS-EYE IMAGE SHOWED A MORE SYMMETRIC CIRCULATION, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS HEDGED HIGHER THAN THE DVORAK ESTIMATES OF T1.5 (25 KNOTS) BASED ON THE ASCAT AND OSCAT DATA. UPPER-LEVEL ANALYSIS REVEALS AN IMPROVING ENVIRONMENT WITH DECREASING (15 TO 20 KNOTS) EASTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY STRONG EQUATORWARD OUTFLOW. RECENT SOUNDINGS FROM GUAM AND 700MB MODEL ANALYSES HAVE CONTINUED TO INDICATE A WEAKENING NEAR- EQUATORIAL RIDGE AND A BUILDING SUBTROPICAL RIDGE (STR) TO THE NORTH AND NORTHEAST, WHICH IS PROVIDING A WESTWARD STEERING INFLUENCE. 3. FORECAST REASONING. A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. AFTER TAU 18 TO 24, ENVIRONMENTAL CONDITIONS ARE FORECAST TO IMPROVE LEADING TO A PERIOD OF SLOW INTENSIFICATION / CONSOLIDATION. DYNAMIC AIDS ARE NOW SPLIT INTO TWO DISCRETE GROUPS WITH NVGM, JGSM AND JENS INDICATING A SHARP RECURVE TRACK OVER IWO-TO AND THE REMAINING TRACKERS INDICATING A MORE GRADUAL RECURVE SCENARIO OVER AND JUST EAST OF THE RYUKYU ISLANDS. ANALYSIS OF NAVGEM FIELDS SHOWS NAVGEM IS PUNCHING THE SYSTEM DIRECTLY INTO THE SUBTROPICAL RIDGE, WHICH IS LIKELY ERRONEOUS, THEREFORE, THE JTWC FORECAST IS ALIGNED WITH THE WESTERN GROUP OF MODEL TRACKERS (AVNO, AEMN, UEMN, ECMF, EEMN, AFUM). THESE MODELS ARE IN FAIR AGREEMENT WITH A 155NM SPREAD IN SOLUTIONS AT TAU 72. C. IN THE EXTENDED PERIOD, THE WESTERN GROUP OF MODELS DIVERGE WITH INCREASED UNCERTAINTY IN THE RECURVE POINT AND TIMING OF THE RECURVE. TD 27W IS FORECAST TO INTENSIFY TO A PEAK OF 95 KNOTS AT TAU 120 DUE TO THE IMPROVED POLEWARD OUTFLOW. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST DUE TO THE BIFURCATION IN MODEL GUIDANCE AND LARGE SPREAD IN THE WESTERN GROUP OF MODEL TRACKERS. AFTER TAU 120, STRONG ZONAL WESTERLIES ARE FORECAST TO PERSIST OVER JAPAN MAKING LANDFALL OVER MAINLAND JAPAN UNLIKELY.// NNNN NNNN