MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (GUCHOL) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 05W (GUCHOL), LOCATED APPROXIMATELY 215 NM NORTH OF PALAU, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS UNDERGONE A BRIEF PERIOD OF DIURNAL FLARING BUT HAS SEEN CONVECTION DECREASE OVER THE PAST THREE HOURS. THE SYSTEM REMAINS COMPACT WITH A REGION OF DEEP CONVECTION, CURRENTLY LOCATED OVER PALAU, MOVING TOWARDS THE LOW LEVEL CIRCULATION CENTER (LLCC). MSI SHOWS OVERSHOOTING TOPS NEAR THE LLCC, HOWEVER RECENT MICROWAVE IMAGERY, INCLUDING A 132102Z SSMIS AND A 132045Z WINDSAT IMAGE, SHOWS A WELL DEFINED EYE DEVELOPING. THE INITIAL POSITION IS BASED ON MSI AND POSITION INFORMATION FROM THE PGTW, KNES, AND RJTD DVORAK FIXES. THE INITIAL INTENSITY IS BASED ON THE PGTW AND RJTD DVORAK ESTIMATES INDICATING 55 KNOTS, WHICH IS SUPPORTED BY THE STRUCTURE NOTED IN PREVIOUSLY MENTIONED MICROWAVE IMAGERY. UPPER LEVEL ANALYSIS INDICATES TS 05W IS LOCATED TO THE SOUTH OF A WEAK INVERTED UPPER LEVEL TROUGH WHICH IS STIFLING POLEWARD OUTFLOW. THE OVERALL POOR UPPER LEVEL ENVIRONMENT IS HINDERING FASTER DEVELOPMENT OVER THE PAST SIX HOURS. VERTICAL WIND SHEAR (VWS) OVER TS 05W IS CURRENTLY AT LOW TO MODERATE LEVELS (10 TO 15 KNOTS). THE SYSTEM IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 05W IS EXPECTED TO CONTINUE TRACKING ALONG THE SOUTHERN TO SOUTHWESTERN PERIPHERY OF THE STEERING STR THROUGH TAU 72. A MID- LATITUDE TROUGH, CURRENTLY LOCATED OVER JAPAN AND EXTENDS TO TAIWAN, WILL WEAKEN THE WESTERN PERIPHERY OF THE STR, CAUSING THE TRACK TO SHIFT TO A WEST-NORTHWESTWARD DIRECTION OVER THE NEXT 48 HOURS. INCREASING UPPER LEVEL SUPPORT FROM THE MID-LATITUDE FLOW IN ASSOCIATION WITH FAVORABLE SEA SURFACE TEMPERATURES (SSTS), WILL ALLOW THE SYSTEM TO DEVELOP THROUGH TAU 72. MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72. THERE IS HIGH CONFIDENCE IN THE TRACK FORECAST THROUGH THIS TIME FRAME. C. BEYOND TAU 72, TS 05W IS FORECAST TO ROUND THE WESTERN PERIPHERY OF THE STR TURNING TO THE NORTH-NORTHWEST BETWEEN TAU 96 AND 120. INCREASING INTERACTION WITH THE MID-LATITUDE FLOW AND DECREASING SSTS, NEAR 25N, WILL CAUSING A SLIGHT WEAKENING OF THE SYSTEM BY TAU 120. MODEL GUIDANCE SPREADS AFTER TAU 72 WITH GFS, NGPS, GFDN, AND EGRR SHOWING A RECURVATURE SCENARIO WITH THE TRACK NEAR KADENA AFB, OKINAWA. THIS FORECAST IS BASED PREDOMINANTLY ON THE CONSENSUS OF AVAILABLE MODEL GUIDANCE. THERE IS HIGH CONFIDENCE WITH THE RECURVATURE SCENARIO. DUE TO THE SPREAD OF THE MODEL GUIDANCE IN THE EXTENDED TAUS, THERE IS LOW CONFIDENCE IN WHETHER THE SYSTEM TRACKS TO THE WEST OR EAST OF OKINAWA.// NNNN NNNN