MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (HALONG) WARNING NR 50// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (HALONG), LOCATED APPROXIMATELY 101 NM SOUTH- SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD AT 7 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS TS 11W MAINTAINING ITS INTENSITY AS IT TRACKS TOWARDS THE SOUTHERN COAST OF SHIKOKU. THE MID-LATITUDE WESTERLIES CONTINUE TO ENHANCE THE POLEWARD OUTFLOW CHANNEL. HOWEVER, DRY AIR ENTRAINMENT FROM THE NORTHEAST AND INCREASED PRESSURE FROM THE WESTERLIES HAMPER INTENSIFICATION. RADAR IMAGERY FROM SHIKOKU INDICATES THAT THE LOW LEVEL CIRCULATION CENTER REMAINS FAIRLY WELL DEFINED WITH THE MAJORITY OF CONVECTION ON THE EASTERN SIDE OF THE STORM. A 091723Z AMSU-B MICROWAVE IMAGE CONFIRMS THE LACK OF DEEP CONVECTION ON THE WESTERN SIDE OF THE STORM AS IT BEGINS ITS EXTRA- TROPICAL TRANSITION (ETT) BY BEING HEAVILY IMPACTED BY THE WESTERIES. THIS ENHANCED CONVECTION ON THE EASTERN SIDE OF THE STORM IS DUE TO THE UPPER LEVEL DIVERGENCE FLOW PROVIDED BY THE WESTERLIES AND SOME OROGRAPHIC LIFT PROVIDED BY THE MOUNTAINOUS REGION OF SOUTHERN SHIKUKO. THE CURRENT INTENSITY HAS BEEN MAINTAINED BASED ON DVORAK ESTIMATES AND SOME OBSERVATIONS FROM THE COASTAL AREAS OF JAPAN'S SMALLEST MAIN ISLAND. TS 11W CONTINUES TO TRACK ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING. B. TS 11W IS EXPECTED TO CONTINUE TO TRACK NORTH-NORTHEASTWARD THROUGH THE FORECAST PERIOD ALONG THE STR AND WILL WEAKEN RAPIDLY AS THE SYSTEM PROGRESSES OVER THE TERRAIN OF SOUTHERN JAPAN AND CONTINUES TO BE SUPPRESSED BY DRY AIR AND SUBSIDENCE FROM THE WEST. BY TAU 12 HALONG WILL CONTINUE TO TAKE ON MORE COLD CORE FEATURES AS THE SYSTEM MOVES INTO THE SEA OF JAPAN, DRIVEN BY THE WESTERIES. ADDITIONALLY, UNFAVORABLE SEA SURFACE TEMPERATURES AMPLIFY THE ALREADY POOR ENVIRONMENTAL CONDITIONS LEADING TO PERSISTENT WEAKENING OF TS 11W. EXPECT THE SYSTEM TO BE COMPLETELY ABSORBED BY THE SHORT-WAVE TROUGH, CURRENTLY NORTH OF THE SYSTEM, AND COMPLETE ETT BY TAU 24. MODEL GUIDANCE CONTINUES TO REMAIN IN VERY GOOD AGREEMENT LEADING JTWCâS HIGH CONFIDENCE TRACK STAYING CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN