The SPC is forecasting ...severe thunderstorms expected over parts of the lower mississippi and tennessee valleys this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 241604 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1004 AM CST THU FEB 24 2011 VALID 241630Z - 251200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF THE LWR MS AND LWR TN VLYS... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA...FROM THE SRN PLNS ENE INTO THE LWR OH VLY... ...SYNOPSIS... STRONG S/W TROUGH NOW SRN HI PLAINS ON TRACK AND WILL RESULT IN SURFACE CYCLOGENESIS ACROSS ERN OK THIS AFTERNOON. SYSTEM BOTH SURFACE AND ALOFT WILL DEEPEN TONIGHT AS LOW CENTER TRACKS ACROSS NRN AR INTO KY. WARM FRONT NOW ACROSS ERN OK INTO CENTRAL AR AND SRN TN WILL LIFT NWD THIS AFTERNOON ALLOWING A MOIST WARM SECTOR TO SPREAD ACROSS MUCH OF LOWER MS VLY INTO TN VALLEY. COMBINATION OF STRENGTHENING WIND FIELD AND ASCENT WITH PROGRESSIVE TROUGH...CONTINUED MOISTURE INFLOW /WITH PW INCREASING TO AOA 1.50 INCHES/...AND DIURNAL HEATING EXPECTED TO SUPPORT AN OUTBREAK OF SVR TSTMS OVER PARTS OF AR/TN AND ADJACENT STATES LATER THIS AFTERNOON INTO TONIGHT. ...SERN OK/ERN TX ENE INTO THE LWR TN VLY/LWR OH VLYS... BY EARLY AFTERNOON MODERATE SFC HEATING WITH TEMPS RISING THRU THE 70S WILL LEAD TO SUFFICIENT INSTABILITY...MLCAPES AOA 1000 J/KG...TO SUPPORT NUMEROUS BANDS/CLUSTERS OF TSTMS ACROSS NERN TX INTO SERN OK/WRN AR AS 90-120 METER MID-LVL HEIGHT FALLS WITH UPR IMPULSE SWEEP ENEWD. RELATIVELY STEEP MID-LVL LAPSE RATES...7C/KM...AND SIZABLE CLOUD-LAYER SHEAR SUGGEST POTENTIAL FOR HAIL AND POSSIBLY SHORT-LIVED BOWING SEGMENTS WITH HIGH WIND AS THE STORMS MOVE/DEVELOP MAINLY ENEWD. A FEW STORMS ALSO MAY FORM NEAR INTENSIFYING WARM FRONT EXTENDING ENE FROM THE DEVELOPING SURFACE LOW ERN OK/WRN AR INTO WRN/MIDDLE TN. WITH LOW TO MID-LVL SHEAR INCREASING SUBSTANTIALLY BY LATER THIS AFTERNOON ASSOCIATED WITH APPROACHING UPR IMPULSE OVERSPREADING THE REGION...ARKANSAS AREA STORMS WILL POSE A THREAT FOR HIGH-IMPACT SVR WEATHER INCLUDING SUPERCELLS WITH BOWING SEGMENTS/HIGH WINDS...LARGE HAIL...AND POSSIBLY STRONG TORNADOES. THE TORNADO THREAT WOULD APPEAR TO BE GREATEST FROM LATE THIS AFTN THROUGH EARLY TONIGHT NEAR WARM FRONT OVER CNTRL/NERN AR AND WRN/MIDDLE TN...WHERE 300-400 M2/S2 0-1KM SRH WILL EXIST INVOF DEEPENING SFC LOW. THERE IS SOME CONCERN THAT THE CURRENT MDT MAY BE A LITTLE FAR N INTO SRN KY GIVEN THE CURRENT VERY COOL BOUNDARY LAYER...HOWEVER WITH THE TRACK OF THE DEEPENING SURFACE LOW ACROSS THIS AREA THERE IS AT LEAST A THREAT OF AN ORGANIZED DAMAGING WIND THREAT AS WELL AS EMBEDDED SUPERCELLS AND TORNADOS. THUS WILL NOT MAKE ANY CHANGES IN THE MDT RISK ATTM. THE STORMS SHOULD EVOLVE INTO AN EXTENSIVE QLCS BY MID-EVE...WITH OVERALL LINE MOVEMENT TO THE ENE ACROSS TN/LWR OH VLYS...AND DEVELOPMENT SWD INTO LA/MS/AL THROUGH THE OVERNIGHT. A CONTINUING THREAT DMGG WIND AND ISOLD TORNADOES LIKELY WILL PERSIST WELL INTO THE NIGHT...ESPECIALLY NEAR TRACK OF SFC LOW ...AND FARTHER S IN AREA OF GREATER SFC-BASED BUOYANCY IN MIDDLE TN...MS...AND NRN/WRN AL. ..HALES/STOPPKOTTE.. 02/24/2011 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z