MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 27W (IN-FA) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 27W (IN-FA), LOCATED APPROXIMATELY 481 NM SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WEST-NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) INDICATES A CONSOLIDATING, COMPACT LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE BANDING. A 190442Z SSMI 85GHZ IMAGE AND A 190548Z SSMIS 91GHZ IMAGE ALSO SHOW A CONSOLIDATING LLCC WITH A WEAK MICROWAVE EYE FEATURE, WHICH SUPPORT THE CURRENT POSITION WITH HIGH CONFIDENCE. DESPITE THE SLIGHTLY IMPROVED ORGANIZATION, THE CURRENT INTENSITY REMAINS ASSESSED AT 55 KNOTS BASED ON DVORAK INTENSITY ESTIMATES OF 55 KNOTS FROM PGTW AND KNES, WHICH IS CONSISTENT WITH THE MICROWAVE EYE FEATURE. UPPER- LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR AND GOOD POLEWARD AND EQUATORWARD OUTFLOW. TS 27W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. CPA DISTANCE AND TIMING TO ANDERSEN AFB HAVE CHANGED SLIGHTLY DUE TO A NORTHWARD ADJUSTMENT TO THE ANALYSIS POSITIONS AND THE RECENT ACCELERATED TRACK SPEEDS. B. TS 27W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD THROUGH TAU 72 UNDER THE DOMINANT STR, WHICH IS EXPECTED TO REMAIN ENTRENCHED TO THE NORTH. TS 27W HAS ACCELERATED TO 16 KNOTS AS IT TRACKS UNDER THE STRONG STR AND IS EXPECTED TO MAINTAIN RELATIVELY FAST TRACK SPEEDS THROUGH TAU 72. DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72. MODEL SPREAD AT CPA (TAU 36) WITH GUAM IS ABOUT 110 NM, THEREFORE, THERE IS SOME UNCERTAINTY IN THE EXACT CPA DISTANCE AND TIMING. TS 27W IS EXPECTED TO INTENSIFY AT A CLIMATOLOGICAL RATE THROUGH TAU 72 TO A PEAK OF NEAR 105 KNOTS. C. IN THE EXTENDED TAUS, TS 27W WILL BEGIN SLOWING AS IT BEGINS TO RE-CURVE POLEWARD IN RESPONSE TO AN APPROACHING MIDLATITUDE TROUGH. EXTRA-TROPICAL TRANSITION IS EXPECTED TO COMMENCE NEAR TAU 108 AS THE SYSTEM BEGINS TO INTERACT WITH THE BAROCLINIC ZONE AND MIDLATITUDE WESTERLIES. THIS INTERACTION SHOULD RESULT IN INCREASING VERTICAL WIND SHEAR, WHICH WILL SERVE TO WEAKEN THE SYSTEM. DYNAMIC MODEL GUIDANCE DIVERGES AFTER TAU 72 DUE TO DIFFERENCES BETWEEN THE MODELS IN THE TIMING AND DEGREE OF THE RE-CURVE, WHICH IS TYPICAL IN THIS SCENARIO, THEREFORE, THERE IS LOW OVERALL CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN