ZCZC SPCSWOMCD ALL ACUS11 KWNS 252314 SPC MCD 252314 KYZ000-TNZ000-260045- MESOSCALE DISCUSSION 0460 NWS STORM PREDICTION CENTER NORMAN OK 0614 PM CDT SAT APR 25 2015 AREAS AFFECTED...CNTRL/SRN KY AND ADJACENT NRN TN CONCERNING...SEVERE THUNDERSTORM WATCH 116... VALID 252314Z - 260045Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 116 CONTINUES. SUMMARY...AN EVOLVING MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE TO BE ACCOMPANIED BY...PRIMARILY...A RISK FOR POTENTIALLY DAMAGING WIND GUSTS AND OCCASIONAL SEVERE HAIL AS IT SPREADS TOWARD THE TENNESSEE BORDER THROUGH 00-02Z. TRENDS WILL CONTINUE TO BE MONITORED FOR THE POSSIBILITY OF AN ADDITIONAL WATCH ACROSS PARTS OF NORTHERN MIDDLE AND EASTERN TENNESSEE. DISCUSSION...FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH THE ELONGATING REMNANTS OF A CYCLONIC CIRCULATION CONTINUES TO SUPPORT INCREASING THUNDERSTORM DEVELOPMENT ACROSS AND SOUTHEAST OF THE OHIO RIVER TO THE WEST/SOUTHWEST OF LOUISVILLE. AIDED BY WEAK TO MODERATE BOUNDARY LAYER CAPE...AND STRONG DEEP LAYER SHEAR BENEATH 40-50 KT WESTERLY 500 MB FLOW...CONVECTION HAS BEEN GROWING UPSCALE INTO AN INCREASINGLY ORGANIZED MESOSCALE CONVECTIVE SYSTEM THE PAST FEW HOURS. ACTIVITY IS EXPECTED TO CONTINUE DEVELOPING EAST SOUTHEASTWARD TOWARD THE TENNESSEE BORDER THROUGH THE 00-02Z TIME FRAME...WITH UPPER FORCING...GENERALLY ALONG AND TO THE SOUTHWEST OF A FAIRLY SHARP SURFACE FRONTAL ZONE. THIS BOUNDARY IS STILL QUASI-STATIONARY SOUTH OF LOUISVILLE INTO THE HIGHER TERRAIN NEAR/NORTH OF JACKSON...WITH RATHER COLD/STABLE BOUNDARY LAYER AIR TO THE NORTH PROVIDING A SUBSTANTIVE LIMITING FACTOR TO SEVERE WEATHER POTENTIAL. HIGHEST SEVERE PROBABILITIES...INCLUDING THE RISK FOR POTENTIALLY DAMAGING WIND GUSTS...IN ADDITION TO SEVERE HAIL...ARE EXPECTED TO REMAIN CONFINED TO A CORRIDOR JUST TO THE WARM SIDE OF THE FRONT...WHERE VERTICAL SHEAR...WHILE STRONG...IS LARGELY UNIDIRECTIONAL. TORNADIC POTENTIAL REMAINS MORE UNCERTAIN...NOT OUT OF THE QUESTION...BUT RELATIVELY LOW IN PROBABILITY. ..KERR.. 04/25/2015 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MRX...JKL...LMK...OHX...PAH... LAT...LON 37818618 37658438 37208344 36618432 36528540 36558669 36808762 37218790 37428644 37818618 NNNN