The SPC is forecasting ...an outbreak of severe thunderstorms expected from the lower mississippi river valley and mid-south region into the southeastern u.s. today and tonight.... Please read the latest public statement about this event.
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SPC AC 021242 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0742 AM CDT THU APR 02 2009 VALID 021300Z - 031200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER MS/AL/WRN TN/WRN-SRN GA/NRN FL... ...THERE IS A SLGT RISK OF SVR TSTMS FROM LA/AR INTO THE OH/TN RIVER VALLEY AND THE SOUTHEAST... ...LOWER MS RIVER VALLEY/MID SOUTH INTO THE SOUTHEASTERN U.S... VERY LITTLE CHANGE NEEDED TO PRIOR FORECAST ATTM AS INTENSE MID/UPPER LEVEL LOW STILL ON TRACK TO DRIVE UNSEASONABLY STRONG MID LEVEL JET /90-100 KT AT H5/ AND HEIGHT FALLS EWD ACROSS THE CENTRAL GULF COAST STATES TODAY. IN ADDITION...SRN STREAM WILL REMAIN QUITE ACTIVE ACROSS THE NRN GULF INTO THE SOUTHEASTERN U.S. AS 70-90 KT SRN STREAM MID LEVEL JET OVERSPREADS VERY MOIST BOUNDARY LAYER AIR ALONG AND SOUTH OF SFC WARM FRONT SLOWLY SHIFTING NWD INTO SRN GA/AL EARLY THIS MORNING. ALTHOUGH THIS ACTIVITY WILL TEND TO LIMIT NWWD EXCURSION OF RICHER GULF MOISTURE INTO MS/AL/TN...FORECAST SOUNDINGS SUGGEST INSTABILITY/MODEST BOUNDARY LAYER MOISTURE WILL STILL BE SUFFICIENT FOR ROBUST SUPERCELL ACTIVITY GIVEN INTENSITY OF APPROACHING IMPULSE AND STRENGTH OF JETS. OVERALL SETUP WILL SUPPORT CONCURRENT...BUT SEPARATE...HIGHER-END SEVERE RISKS THROUGH MUCH OF THE DAY. SRN STREAM AREA HAS REMAINED ACTIVE FOR A COUPLE DAYS AND HAS SUPPORTED OVERALL WEAKENING LAPSE RATES AS EVIDENCED AT TLH THIS MORNING. REGARDLESS...PRONOUNCED LOW LEVEL AND DEEP LAYER SHEAR WILL REMAIN VERY SUPPORTIVE OF ORGANIZED/LONG-LIVED STORMS...INCLUDING TORNADIC SUPERCELLS. TORNADO THREAT WILL REMAIN ENHANCED ALONG AND SOUTH OF SURFACE WARM FRONT...WHICH SHOULD LIFT NWD INTO CENTRAL GA THIS MORNING. ATTENDANT TORNADO THREAT WILL ALSO OVERSPREAD NERN FL/SERN GA AND PERHAPS PORTIONS OF SRN SC THROUGH THE DAY AS WELL. MORNING STORMS THROUGH DAYBREAK AHEAD OF MAIN IMPULSE OVER ERN TX HAVE STRUGGLED WITHIN RELATIVELY DRY AIR /PWS AOB 1 INCH/ AND MODEST CAPPING STILL IN PLACE. LEADING EDGE OF DEEP ASCENT SHOULD SUPPORT MORE ROBUST CONVECTION BY THE MID TO LATE MORNING ACROSS THE LOWER MS RIVER VALLEY AS IT BEGINS INTERACTING WITH GREATER MOISTURE AND WEAKENING CINH. NWD PORTION OF THIS LINE WILL ALSO INCREASE IN COVERAGE/INTENSITY INTO THE MID SOUTH BY THE EARLY TO MID AFTERNOON FOR THE SAME REASONS. EXTREME SHEAR REMAINS VERY SUPPORTIVE OF TORNADIC SUPERCELLS...POTENTIALLY SIGNIFICANT/LONGER-LIVED. HOWEVER...FAST MOVING/DEEP ASCENT MAY ALSO SUPPORT EVOLUTION INTO LINEAR SEGMENTS...ESPECIALLY INTO THE MID SOUTH/OH VALLEY REGIONS WHERE MID LEVEL FLOW BACKS IMMEDIATELY AHEAD OF UPPER SYSTEM. THESE THREATS WILL RAPIDLY MOVE ENEWD THROUGH THE EVENING WITH GRADUALLY DIMINISHED SEVERE THREAT NWD ACROSS THE OH RIVER VALLEY AND EWD INTO THE SRN APPALACHIANS THROUGH THE EVENING. EXTREME SHEAR MAY ALSO SUPPORT LATE PERIOD INCREASE IN SEVERE RISK AS SYSTEM SKIRTS THE SERN U.S. HOWEVER...IMPACTS OF THIS INTENSE NRN STREAM SYSTEM ON THE SOUTHEASTERN U.S. REMAIN QUESTIONABLE OVERNIGHT DEPENDANT ON AFFECTS OF WIDESPREAD STRONG/SEVERE THUNDERSTORMS THROUGH THIS AFTERNOON ON RESIDUAL MOISTURE/INSTABILITY FIELDS. ..EVANS/GARNER.. 04/02/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z