WDPN32 PGTW 240300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W (MEARI)// /WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 07W (MEARI), LOCATED APPROXIMATELY 365 NM SOUTH-SOUTHWEST OF KADENA AIR BASE, JAPAN, HAS TRACKED NORTH- NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. RECENT MULTISPECTRAL MICROWAVE SATELLITE IMAGERY SHOWS AN EXPANSIVE LOW LEVEL CIRCULATION CENTER WITH DEEP CONVECTIVE BANDING ALONG THE SOUTHERN AND EASTERN PERIPHERIES. MICROWAVE SATELLITE DATA SHOWS SMALL-SCALE VORTICES CONTINUING TO DEVELOP AND ROTATE AROUND THE PERIPHERY OF THE BROAD LOW TO MIDDLE-LEVEL CIRCULATION OF TS 07W. THE PRIMARY CIRCULATION HAS CONSOLIDATED OVER THE PAST 12 HOURS, AND IS CLEARLY EVIDENT IN THE 232035Z SSMI IMAGE UPON WHICH THE CURRENT POSITION IS PARTIALLY BASED. THE CURRENT INTENSITY OF 50 KNOTS IS A BIT HIGHER THAN THE DVORAK T-NUMBER ESTIMATES RANGING FROM 2.5 TO 3.0 SUGGEST, BUT IS CONSISTENT WITH CONVECTIVE STRUCTURE EVIDENT IN MICROWAVE SATELLITE IMAGERY. TS 07W CONTINUES TO TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE TO THE EAST. INTERACTION WITH AN UPPER-LEVEL LOW DURING THE PAST 12 HOURS HAS INTRODUCED MODERATE VERTICAL WIND SHEAR AND SUBSIDENCE ALOFT NEAR THE LOW LEVEL CIRCULATION CENTER (LLCC), LIMITING INTENSIFICATION TO A SLOW RATE. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN FORECAST PHILOSOPHY FROM THE PREVIOUS ISSUANCE OF THE PROGNOSTIC REASONING MESSAGE. B. TS 07W WILL CONTINUE TRACKING POLEWARD ALONG THE WESTERN PERIPHERY OF THE CURRENT STEERING RIDGE THROUGH TAU 72. PASSAGE OVER WARM WATER THROUGH TAU 30 ALONG WITH STRONG EQUATORWARD AND EASTWARD OUTFLOW ENHANCED BY A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE SOUTHEAST WILL SUPPORT INTENSIFICATION IN THE NEAR TERM. HOWEVER, MODERATE VERTICAL WIND SHEAR AND SUBSIDENCE ALOFT INTRODUCED BY INTERACTION WITH AN UPPER-LEVEL LOW AND CONTINUING CONSOLIDATION OF THE BROAD LLCC WILL LIMIT INTENSIFICATION. INTENSITY IS EXPECTED TO PEAK AROUND TAU 36, AROUND WHICH TIME THE SYSTEM WILL CROSS THE 26 DEGREE CELSIUS ISOTHERM AND PROCEED OVER COOLER WATER. BY TAU 48, TS 07W WILL INTERACT WITH A MID-LATITUDE TROUGH CURRENTLY ANALYZED OVER CENTRAL CHINA AND BEGIN EXTRATROPICAL TRANSITION (ET). INCREASING VERTICAL WIND SHEAR, PASSAGE OVER COOL WATER AND, AFTER TAU 60, PASSAGE OVER LAND WILL CAUSE TS 07W TO WEAKEN AS IT UNDERGOES ET. THE SYSTEM WILL COMPLETE EXTRATROPICAL TRANSITION BY TAU 72. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE FORECAST TRACK. THE MODEL TRACKERS DO DIVERGE SLIGHTLY AFTER TAU 24, BUT ALL CONSENSUS MEMBERS INDICATE EVENTUAL LANDFALL OCCURRING ON THE KOREAN PENINSULA. THIS FORECAST LIES SLIGHTLY TO THE WEST OF THE NUMERICAL MODEL CONSENSUS, CONSISTENT WITH CURRENT EXPECTATIONS OF A MERIDIONAL STEERING PATTERN AND PREVIOUS MODEL AND SUBJECTIVE FORECAST TRENDS. C. BETWEEN TAU 72 AND TAU 96, THE FORMER TS 07W WILL ACCELERATE INTO THE MID-LATITUDE WESTERLY FLOW PATTERN AS AN EXTRATROPICAL LOW PRESSURE SYSTEM.// NNNN