The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi...lower tennessee...and lower ohio valleys this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 011256 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0756 AM CDT SAT MAY 01 2010 VALID 011300Z - 021200Z ...THERE IS A HIGH RISK OF SVR TSTMS OVER PARTS OF AR...MS...TN AND THE MO BOOTHEEL... ...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK AREA OVER PARTS OF THE LWR MS...LWR TN AND LWR OH VLYS... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE ABOVE AREAS FROM E TX NEWD INTO THE UPR OH VLY... ...SYNOPSIS... HIGH AMPLITUDE CNTRL STATES TROUGH WILL MOVE ONLY SLOWLY E THIS PERIOD AS ASSOCIATED NRN PLAINS UPR LOW REMAINS QSTNRY AND ATTENDANT SHORTWAVE TROUGH NOW ENTERING CHIHUAHUA SHEARS ENE ACROSS W TX...OK...AND...BY SUN MORNING...KS/MO. MID/UPR LVL SPEED MAX WITH THE CHIHUAHUA SYSTEM WILL REDEVELOP NE INTO N TX/OK BY THIS EVE...AND FURTHER EXPAND NE ACROSS MID MS VLY/UPR GRT LKS EARLY SUN. AT THE SFC...MAIN FRONTAL ZONE WILL REMAIN NEARLY STNRY FROM LWR MI TO E TX TODAY...WITH COMPOSITE OUTFLOW BOUNDARY LEFT BY OVERNIGHT STORMS LIKELY TO LIFT SLOWLY N ACROSS AR AND THE LWR TN VLY. A WAVE SHOULD FORM OVER NE TX OR THE ARKLATEX LATER TODAY...NEAR INTERSECTION OF OUTFLOW BOUNDARY WITH FRONT. THE WAVE SHOULD TRACK NNE INTO THE LWR OH VLY TONIGHT/EARLY SUN. ...E TX/LWR MS VLY INTO THE LWR TN/LWR OH VLYS THROUGH TONIGHT... WSW-ENE ORIENTED QLCS OVER THE LWR MS AND TN VLYS MAY FURTHER WEAKEN LATER THIS MORNING AS WEAK HEIGHT RISES OVERSPREAD REGION AND SFC TEMPERATURES REACH DIURNAL MINIMUMS. SFC HEATING AND CONTINUED INFLOW OF VERY MOIST AIR SHOULD...HOWEVER...SUPPORT REDEVELOPMENT OF SOME STORMS IN WHAT IS LEFT OF THE MCS BY EARLY AFTN...WITH ADDITIONAL DEVELOPMENT POSSIBLE TO ITS S OVER SRN/CNTRL AR AND NRN MS. OTHER STORMS MAY FORM LATER THIS MORNING AND THIS AFTN OVER NE TX AND SE OK...AS ISENTROPIC ASCENT DOWNSTREAM FROM CHIHUAHUA UPR IMPULSE INCREASES ATOP SHALLOW FRONT. COMBINATION OF DAYTIME HEATING AND RICH MOISTURE /PW 1.50-1.75 INCHES WITH SFC DEWPOINTS IN THE LOW 70S/ SHOULD ALLOW FOR SUBSTANTIAL LOW LVL DESTABILIZATION ALONG AND S OF MCS OUTFLOW BOUNDARY AND E OF FRONT...WITH SBCAPE EXPECTED TO BE AOA 2000 J/KG WITH MINIMAL CINH. COUPLED WITH STRONGLY-SHEARED LOW TO MID LVL WIND FIELD...SETUP COULD SUPPORT SCTD SUSTAINED SUPERCELLS WITH TORNADOES/SVR HAIL. AS THE CHIHUAHUA SYSTEM AND ASSOCIATED MID/UPR LVL SPEED MAX /WITH 250 MB FLOW AROUND 150 KTS/ CONTINUE NEWD LATER THIS AFTN AND TONIGHT...DOWNSTREAM SLY LLJ SHOULD MARKEDLY INCREASE OVER THE LWR MS AN TN VLYS. THIS SHOULD SUPPORT ENHANCEMENT OF EXISTING STORMS...AS WELL AS ADDITIONAL DEVELOPMENT...FROM THE ARKLATEX E/NEWD INTO THE LWR TN AND LWR OH VLYS THROUGH THE EVENING/OVERNIGHT. 60 KT DEEP SWLY SHEAR AND DEEPLY-MOIST ENVIRONMENT WITH NEARLY UNIDIRECTIONAL MID/UPR LVL FLOW WILL BE FAVORABLE FOR SUPERCELL ECHO TRAINING/LEWPS AS SFC WAVE TRACKS NE TOWARD THE OH VLY. THE SETUP ULTIMATELY MAY SUPPORT MULTIPLE CORRIDORS HAVING A POTENTIAL FOR STRONG TORNADOES FROM MUCH OF AR AND NRN MS NEWD INTO WRN/CNTRL TN...WRN/CNTRL KY AND PERHAPS SRN IL/SRN INDIANA TONIGHT/EARLY SUN. ...MIDDLE/UPR OH VLY... ERN END OF AFOREMENTIONED QLCS SHOULD CONTINUE E ACROSS ERN KY AND CNTRL/ERN OH THROUGH LATER THIS MORNING. DIURNAL DESTABILIZATION AND MODEST LOW LVL MOISTURE INFLOW MAY SUPPORT A MODEST SVR THREAT /DMGG WINDS OR AN ISOLD TORNADO/ THROUGH EARLY EVE. ADDITIONAL STRONG TO SVR ACTIVITY MAY AFFECT THE REGION LATE IN THE PERIOD /AFTER 06Z SUN/ AS SFC WAVE MOVES NE TOWARD THE LWR OH VLY AND ASSOCIATED LLJ STRENGTHENS OVER ERN KY/OH. ..CORFIDI/GARNER.. 05/01/2010 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z