WDPN31 PGTW 281500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (KONG-REY) WARNING NR 11// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 14W (KONG-REY), LOCATED APPROXIMATELY 177 NM SOUTH-SOUTHEASTWARD OF TAIPEI, TAIWAN, HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE (EIR) IMAGERY DEPICTS A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH PERSISTENT DEEP CONVECTION OVERHEAD AS WELL AS RECENTLY DEVELOPED DEEP CONVECTION SHEARED TO THE SOUTHWEST OF THE LLCC. A 281202Z 37 GHZ SSMIS MICROWAVE IMAGE REVEALS SEVERAL TIGHTLY WRAPPED CONVECTIVE BANDS SPIRALING INTO THE LLCC WITH THE BULK OF THE DEEP CONVECTION TO THE SOUTH AND SOUTHWEST OF THE CIRCULATION CENTER. THE INITIAL POSITION IS BASED ON THE EIR AND THE MICROWAVE IMAGE WITH FAIR CONFIDENCE. THE INITIAL INTENSITY OF 50 KNOTS IS BASED ON CONGRUENT DVORAK INTENSITY ESTIMATES RANGING FROM 45 TO 55 KNOTS. UPPER-LEVEL ANALYSIS INDICATES TS 14W IS JUST SOUTH OF THE SUBTROPICAL RIDGE (STR) AXIS IN AN AREA OF MODERATE TO HIGH (20-30 KNOTS) NORTHEASTERLY VERTICAL WIND SHEAR (VWS), WHICH IS OFFSET BY STRONG WESTWARD AND EQUATORWARD OUTFLOW. TS 14W IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY OF THE STR. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 14W IS EXPECTED TO CONTINUE TRACKING NORTHWESTWARD UNDER THE INFLUENCE OF THE STR THROUGH TAU 24. AFTER TAU 24, A MID- LATITUDE TROUGH APPROACHING FROM THE NORTHWEST IS EXPECTED TO WEAKEN THE STR AND CAUSE THE CYCLONE TO RECURVE NORTHEASTWARD. TS 14W IS EXPECTED TO GRADUALLY WEAKEN THROUGH THE REMAINDER OF THE FORECAST PERIOD. THOUGH VWS IS FORECAST TO GRADUALLY DIMINISH AS THE SYSTEM DRIFTS NORTH, LAND INTERACTION DUE TO THE CLOSE PROXIMITY TO TAIWAN AND THE EAST COAST OF CHINA WILL DISRUPT THE LOW-LEVEL INFLOW AND AID IN THE WEAKENING. ADDITIONALLY, THE APPROACHING MID-LATITUDE TROUGH IS FORECAST TO FURTHER WEAKEN THE SYSTEM, AT APPROXIMATELY TAU 36, AS IT ENCOUNTERS INCREASED VWS WITH THE ONSET OF STRONG WESTERLIES. THE PASSAGE OF THE MID-LATITUDE TROUGH WILL BEGIN EXTRATROPICAL TRANSITION AT TAU 48 AND COMPLETE TRANSITION BY TAU 72. C. AFTER TAU 72, TS 14W IS EXPECTED TO ACCELERATE NORTHEASTWARD ACROSS THE SOUTHEAST COAST OF JAPAN AS A COLD-CORE EXTRATROPICAL SYSTEM. DYNAMIC MODEL GUIDANCE HAS FALLEN INTO GOOD AGREEMENT THROUGHOUT THE FORECAST TRACK, THE ONLY EXCEPTION BEING GFDN, WITH ONLY SLIGHT VARIATIONS IN TRACK SPEED AND INTENSITY AT THE LATER TAUS. SOME UNCERTAINTY REMAINS AROUND THE RECURVE POINT AS THERE IS THE POTENTIAL FOR THE SYSTEM TO TRACK FURTHER WESTWARD, TOWARDS THE EAST COAST OF CHINA, AS THE STR MAY REMAIN FAIRLY STRONG OVER THE NEXT 12 TO 36 HOURS. THIS COULD CAUSE TRACK SPEEDS TO SLOW BETWEEN TAU 12 AND 36 AND THE STORM TO MOVE FURTHER WEST BEFORE RECURVING. THE ECMWF TRACK FORECAST HAS FALLEN IN LINE WITH THE BULK OF THE MUTLI-MODEL CONSENSUS WHILE THE GFS FORECAST CONTINUES TO EXHIBIT THE MOST WESTWARD RECURVING TRACK. THE JTWC FORECAST IS LAID BETWEEN THE MULTI-MODEL CONSENSUS AND ECMWF/GFS IN THE EARLY TAUS AND IS SLIGHTLY FASTER THAN AND TO THE RIGHT OF CONSENSUS, DUE TO A KNOWN HISTORICAL BIAS TO ACCOUNT FOR THE HIGH TERRAIN IN JAPAN, IN THE EXTENDED TAUS. THERE IS LOW CONFIDENCE IN THE FORECAST TRACK DUE TO THE UNCERTAINTY AROUND THE RECURVE POINT.// NNNN