MKC AC 241233   STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC.   VALID 241300Z - 251200Z THERE IS A HIGH RISK OF SVR TSTMS TODAY AND EARLY TONIGHT ACROSS SERN MO...PARTS OF CNTRL/SRN IL...MUCH OF IND...SRN MI...WRN OH AND NWRN KY. THE HIGH RISK AREA IS TO THE RIGHT OF A LINE FROM 20 W CLE 25 NW ZZV 35 NW HTS 40 WSW HOP 30 NNW ARG 10 ENE TBN 15 WNW STL BMI 25 SSE CGX 15 WNW LAN 15 E MTC.   SURROUNDING THE HIGH RISK AREA...THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 ENE ROC 45 WSW ELM 20 NNE EKN 15 WNW BKW 25 SW TYS 15 NNW BHM MEI 35 W JAN 40 SW GLH 45 WSW PBF 30 N HOT 20 SE UMN 45 S SZL 30 NNE COU 25 ESE UIN 10 W PIA 35 S RFD 30 W MKE 20 SSE MTW 35 NNW APN. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SSE HUM 25 SSW ESF 30 NNE SHV 10 SW FSM 40 SSE OJC 40 NE SZL 40 SE OTM 10 E CID 15 WSW VOK 55 NNE EAU 20 ESE DLH 40 SW HIB 20 SW BJI 25 W RRT ...CONT... 50 WNW 3B1 35 WSW BHB.   *** A SIGNIFICANT SEVERE WEATHER OUTBREAK EXPECTED TODAY ACROSS THE MID MS AND OH VLYS INTO THE SRN GREAT LAKES REGION*** ...SYNOPSIS... A VERY DYNAMIC SYSTEM WILL AFFECT THE OH VLY AND GREAT LAKES REGION TODAY AND TONIGHT. THE UPPER FLOW WILL BECOME INCREASINGLY DIVERGENT ACROSS THESE REGIONS AS THE MIDLEVEL TROUGH OVER THE CNTRL PLAINS BECOMES NEGATIVELY TILTED. THE MIDLEVEL FLOW WILL BEGIN TO INCREASE BY LATER THIS MORNING/AFTERNOON...FIRST AS A MODEST SPEED MAX TRANSLATES NEWD FROM THE SRN PLAINS INTO THE LOWER OH VLY...AND THEN AS THE MIDLEVEL TROUGH MIGRATES EWD. AT THE SURFACE...LOW OVER NRN MN WILL DEEPEN OVER 15 MB IN THE 24 HRS AFTER 12 UTC TODAY...MOVING INTO SWRN ONTARIO OVERNIGHT. ATTENDANT STRONG COLD FRONT TRAILING SWD FROM THE LOW WILL TRANSLATE TO IN...WRN KY...WRN TN AND NRN MS BY SUNSET...THEN ACROSS THE APPALACHIANS BY THE END OF THE PERIOD. A SECONDARY WEAKER LOW WILL MOVE ALONG THE FRONT FROM OK THIS MORNING... REACHING THE MO BOOTHEEL THIS AFTERNOON AND INTO OH THIS EVENING. ...LOWER MS VLY/OH VLY INTO THE SRN GREAT LAKES REGION... TSTMS CONTINUE EARLY THIS MORNING ACROSS THE OH VLY...WITH AN OUTFLOW BOUNDARY EXTENDING WWD FROM CNTRL KY INTO PARTS OF CNTRL MO. CURRENT TSTMS SHOULD WEAKEN AS THEY MOVE INTO A MORE STABLE ENVIRONMENT LATER THIS MORNING.   ADDITIONAL TSTMS SHOULD INITIATE INVOF OF APPROACHING COLD FRONT AS IT INTERSECTS WITH THE SERN MO PORTION OF THE OUTFLOW BOUNDARY BY MID/LATE MORNING. 06 UTC ETA AND LATEST RUC40 AGREE THAT UVV WILL INCREASE RAPIDLY AS EXIT REGION OF THE SRN PLAINS JETLET BECOMES COINCIDENT WITH LOW LEVEL THETAE ADVECTION/CONVERGENCE NEAR THE BOUNDARIES. OTHER TSTMS ARE LIKELY TO DEVELOP/INTENSIFY NWD ACROSS ERN MO AND WRN IL THIS MORNING AS THE COLD FRONT ADVANCES EWD. MOIST/UNSTABLE AIR MASS ACROSS THE LOWER MS VLY WILL CONTINUE TO ADVECT NEWD INTO THE OH VLY AND SRN GREAT LAKES THROUGH THE DAY. 12 UTC UPSTREAM SOUNDINGS EXHIBITED VERY STEEP MIDLEVEL LAPSE RATES. GIVEN INCREASING SWLY FLOW ALOFT...THESE LAPSE RATES ADVECTING ATOP 60S SURFACE DEW POINTS WILL CONTRIBUTE TO AFTERNOON SBCAPE VALUES RANGING FROM 1000-1500 J/KG ACROSS THE SRN GREAT LAKES TO NEAR 2000 J/KG OVER THE OH VLY.   PRIND THAT STRONG/SEVERE TSTMS WILL QUICKLY ADVANCE NEWD FROM SERN MO INTO PARTS OF CNTRL/SRN IL...WRN/NRN KY...IND...WRN OH AND SRN LOWER MI DURING THE AFTERNOON. FORECAST HODOGRAPHS INDICATE STRONG DEEP LAYER SHEAR OF 50-60 KTS OVERSPREADING THE WARM SECTOR LATE THIS MORNING INTO THE AFTERNOON...SO SUPERCELLS ARE LIKELY ALONG WITH BOW ECHOES EMBEDDED WITHIN LINEARLY-ORGANIZED CLUSTERS. MORE IMPORTANTLY...HOWEVER...IS THE FAIRLY WIDESPREAD AREA OF 0-1KM SHEAR OF 20-40 KTS AND 3KM HELICITY VALUES OF 200-500 M2/S2 EXPECTED ACROSS PARTS OF THE AREA...SUPPORTIVE OF STRONG/VIOLENT TORNADOES. ATTM...THE GREATEST POTENTIAL FOR DISCREET SUPERCELLS APPEARS TO EXIST INVOF OF THE OUTFLOW BOUNDARY THAT SHOULD LIFT ENEWD ACROSS THE OH VLY. SHORT TERM MODEL SUITE IS ALSO INDICATING THAT THE LOW LEVEL FLOW WILL BACK ACROSS THE OH VLY THIS AFTERNOON AS STRONG PRESSURE FALLS OCCUR OVER THE GREAT LAKES. PRIND THAT A CORRIDOR FROM SERN MO INTO SRN IL...IND...NWRN KY AND INTO SWRN- NCNTRL OH WILL HAVE THE HIGHEST TORNADO THREAT.   ELSEWHERE ALONG THE COLD FRONT...TSTMS WILL LIKELY BE MORE LINEAR IN NATURE NWD INTO LOWER MI...WITH SIGNIFICANT DAMAGING WINDS/LARGE HAIL THE MAIN THREATS. HOWEVER...EMBEDDED SUPERCELLS ARE STILL POSSIBLE WITH ISOLD TORNADOES NOT OUT OF THE QUESTION.   TSTMS WILL LIKELY BEGIN TO WEAKEN AFTER SUNSET AS THEY MOVE EWD INTO THE APPALACHIAN MOUNTAINS GIVEN STABILIZATION OF THE BOUNDARY LAYER. DAMAGING WIND THREAT...HOWEVER...WILL LIKELY CONTINUE INTO PARTS OF WRN PA AND WV.   FARTHER SWD...A BAND OF TSTMS WILL LIKELY BACKBUILD SWWD INTO PARTS OF WRN TN...NRN/CNTRL MS AND ADVANCE SEWD INTO MIDDLE TN AND AL OVERNIGHT. DAMAGING WINDS/HAIL ALSO ARE POSSIBILITY OVER THESE AREAS INTO THE EVENING HOURS GIVEN STRENGTH OF FRONTOGENESIS AND DEEP LAYER SHEAR OF AOA 45 KTS. ..RACY.. 10/24/01