MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (FOURTEEN) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 14W (FOURTEEN), LOCATED APPROXIMATELY 366NM EAST-SOUTHEAST OF KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SYMMETRIC, CENTRAL CONVECTION OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LOW LEVEL CIRCULATION (LLC) EVIDENT IN WIND FIELD DATA FROM A TIMELY 201053Z ASCAT-A PASS. THE INITIAL INTENSITY OF 35 KTS IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON THE 35 KTS WINDS PRESENT ALONG THE EASTERN PERIPHERY OF THE LLC IN THE ASCAT-A DATA AND IS HEDGED SLIGHTLY HIGHER THAN MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T2.0 (30 KTS, PGTW AND KNES). THE SYSTEM HAS SUBTROPICAL CHARACTERISTICS. THE INTENSITY OF THE WIND FIELD, FOR EXAMPLE, IS HIGHLY ASYMMETRIC WITH HIGH (30+ KTS) WINDS ALONG THE EASTERN PERIPHERY AND WEAKER (15 KTS) WINDS ALONG THE WESTERN PERIPHERY. FURTHERMORE, THE OUTFLOW FROM THE SYSTEM HAS ALREADY TAPPED INTO THE DEEP WESTERLY FLOW ASSOCIATED WITH THE JET OVER HONSHU, JAPAN. DESPITE THIS, ANALYSIS OF THE WIND FIELD AND THERMAL PROFILE REVEALS THAT THE SYSTEM MAINTAINS MOSTLY TROPICAL CHARACTERISTICS. ENVIRONMENTAL ANALYSIS FURTHER REVEALS AN ENVIRONMENT THAT IS FAVORABLE FOR DEVELOPMENT WITH LOW (10-15 KTS) VERTICAL WIND SHEAR, WARM (30-31 CELSIUS) SEA SURFACE TEMPERATURES (SST) AND WELL ESTABLISHED POLEWARD AND EQUATORWARD OUTFLOW ALOFT. THE SYSTEM IS NEARLY QUASISTATIONARY AND IS TRACKING THROUGH A WEAK STEERING ENVIRONMENT DUE TO ITS PLACEMENT INSIDE A COL REGION THAT IS INDUCED BY A SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND A SECOND STR POSITIONED TO THE WEST-SOUTHWEST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE FOR THIS SYSTEM AND SETS THE FORECAST PHILOSOPHY. B. TS 14W WILL CONTINUE TRACKING GENERALLY NORTHWARD UNDER THE INFLUENCE OF THE TWO AFOREMENTIONED STEERING RIDGES. THE SYSTEM WILL POSSIBLY TAKE ON ADDITIONAL SUBTROPICAL CHARACTERISTICS DURING THIS TIME, HOWEVER THE FAVORABLE CONDITIONS WILL ALLOW IT TO INTENSIFY TO 55 KTS BY 24. INCREASING VWS AFTER TAU 24 WILL STIFLE FURTHER INTENSIFICATION, HOWEVER THE ENVIRONMENT WILL REMAIN OVERALL FAVORABLE THROUGH TAU 36 AND ALLOW THE SYSTEM TO MAINTAIN 55 KTS INTENSITY. BY TAU 48 INCREASING (20+ KTS) VWS WILL LEAD TO A GRADUAL WEAKENING TREND TO 50 KTS. ADDITIONALLY, THE SYSTEM WILL BEGIN TO ROUND THE STR TO THE EAST WHICH WILL THEREAFTER BE THE PRIMARY STEERING MECHANISM. AFTER TAU 48 THE SYSTEM WILL INTERACT FURTHER WITH THE AFOREMENTIONED WESTERLY FLOW ALOFT AND WILL BEGIN EXTRATROPICAL TRANSITION (ETT). AS IT CONTINUES TO TRACK GENERALLY NORTHEASTWARD AFTER THIS TIME, IT WILL BECOME FURTHER EMBEDDED IN THE WESTERLY FLOW AND CONTINUE ETT. NUMERICAL MODEL GUIDANCE IS IN POOR OVERALL AGREEMENT WITH A 550 NM SPREAD IN ACROSS TRACK SOLUTIONS BY TAU 72. THE SPREAD IN MODEL SOLUTIONS IS LIKELY DUE TO UNCERTAINTY IN THE TIMING OF AN INCOMING SHORTWAVE TROUGH PROPAGATING FROM THE NORTHWEST THAT TEMPORARILY ERODES THE STEERING RIDGES. THIS SPREAD IN MODEL SOLUTIONS LENDS OVERALL POOR CONFIDENCE IN THE INITIAL PORTION OF THE JTWC FORECAST TRACK. C. AFTER TAU 72 THE SYSTEM WILL CONTINUE TO TRACK ALONG THE WEST- NORTHWESTERN PERIPHERY OF THE STR POSITIONED TO THE EAST. BY TAU 96 IT WILL BECOME FULLY EMBEDDED IN THE BAROCLINIC ZONE AND COMPLETE ETT. THE INTENSITY IS FORECAST TO WEAKEN TO 40 KTS BY THIS TIME. NUMERICAL MODEL SOLUTIONS CONTINUE TO DIVERGE FURTHER WITH A SPREAD OF 630 NM BY TAU 96. THIS CONTINUED HIGH DEGREE OF SPREAD IN SOLUTIONS LENDS POOR CONFIDENCE IN THE OVERALL JTWC FORECAST TRACK. // NNNN NNNN