MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (EIGHT) WARNING NR 04// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 08W (EIGHT), LOCATED APPROXIMATELY 162 NM SOUTHWEST OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR), IN ASSOCIATION WITH RADAR IMAGERY FROM GUAM, DEPICTS AN INCREASE IN ORGANIZATION OF THE LOW LEVEL CIRCULATION CENTER (LLCC) WITH BUILDING CONVECTIVE BANDING ALONG THE EASTERN AND NORTHERN QUADRANTS. THE POSITIONING OF THE LLCC HAS BEEN DIFFICULT DUE TO THE BROAD EAST-WEST ELONGATION OF THE LLCC OVER THE PAST 12 HOURS. A RECENT 031558Z AMSU-B MICROWAVE IMAGE IS INDICATING IMPROVING LOW LEVEL STRUCTURE AND SUPPORTS THE EIR. BASED ON THE RECENT INCREASE IN DVORAK ESTIMATES FROM PGTW AND KNES, INDICATING 2.5/2.5 (35 KNOTS), AND THE IMPROVED ORGANIZATION, THE SYSTEM HAS BEEN UPGRADED TO A TROPICAL STORM. A DEEP LAYERED SUBTROPICAL RIDGE (STR) REMAINS THE DOMINANT STEERING INFLUENCE FOR TS 08W. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 08W IS FORECAST TO TRACK WEST-NORTHWESTWARD TO NORTHWESTWARD THROUGH TAU 72 ALONG THE SOUTHERN PERIPHERY OF THE STR. MID-LATITUDE TRANSITORY LOWS WILL BEGIN TO MODIFY THE WESTERN EXTENT OF THE STR, ALLOWING FOR AN INCREASED NORTH-NORTHWESTWARD TRACK AROUND TAU 72. MODEL GUIDANCE HAS BECOME SLIGHTLY MORE CONSISTENT, OVER THE PAST 12 HOURS, WITH TS 08W TURNING TO THE NORTH APPROXIMATELY 120 NM EAST OF OKINAWA, BUT THE POSSIBILITY OF ADDITIONAL WESTWARD DRIFT WILL BE MONITORED CLOSELY TO IDENTIFY AND DECREASE IN CPA TO OKINAWA. TS 08W WILL CONTINUE TO INTENSIFY THROUGH TAU 96 AS IT TRACKS OVER VERY FAVORABLE SEA SURFACE TEMPERATURES (SST), WITH AN IMPROVING UPPER LEVEL OUTFLOW PATTERN. C. IN THE EXTENDED TAUS, TS 08W IS EXPECTED TO TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF THE STR, TURNING TO THE NORTH- NORTHEAST BY TAU 120 AS THE STR BEGINS TO SEE INCREASED INFLUENCE FROM A MID-LATITUDE SHORTWAVE TROUGH. WITH THE EXCEPTION OF GFDN, WHICH IS SLOWER AND FURTHER WEST, THE DYNAMIC GUIDANCE IS IN GOOD AGREEMENT. TS 08W IS EXPECTED TO INTENSIFY TO A PEAK INTENSITY OF 105 KNOTS AT TAU 96 DUE TO IMPROVED POLEWARD OUTFLOW. BY TAU 120 THE INCREASED MID-LATITUDE INTERACTION, DECREASING SST VALUES, AND THE START OF LAND INTERACTION WILL BEGIN THE WEAKENING PROCESS. OVERALL, THERE IS LOW CONFIDENCE IN THE FORECAST TRACK DUE TO UNCERTAINTY IN THE INITIAL POSITION AND TIMING OF THE RECURVE.// NNNN NNNN