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 020556 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1256 AM CDT THU APR 02 2009 VALID 021200Z - 031200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS WRN TN...MS...AL...SRN GA...NRN FL... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM ERN TX INTO THE OH VALLEY AND COASTAL CAROLINAS... ...SIGNIFICANT SEVERE WEATHER EXPECTED ACROSS MUCH OF THE GULF COAST STATES INTO THE WRN TN VALLEY... EARLY MORNING SATELLITE/RADAR IMAGERY CLEARLY DEPICT CENTER OF UPPER LOW OVER NERN NM NEAR TCC...DIGGING SEWD IN LINE WITH 00Z MODEL GUIDANCE. THIS FEATURE SHOULD MOVE ALONG THE RED RIVER THIS MORNING BEFORE EJECTING NEWD ACROSS AR INTO WRN TN DURING THE EVENING HOURS AS 90KT+ MID LEVEL JET ROTATES INTO MS/AL. NEEDLESS TO SAY LOW LEVEL RESPONSE TO THIS UPPER JET WILL INTENSIFY AS SFC LOW EVOLVES OVER AR BY 18Z WITH SUBSEQUENT MOVEMENT AND DEEPENING EXPECTED INTO WRN TN BEFORE LIFTING NEWD ALONG THE OH RIVER TONIGHT. MARITIME AIRMASS HAS YET TO SURGE INLAND SIGNIFICANTLY ALONG THE GULF COAST WITH GREATEST NWD MOVEMENT NOW OCCURRING ACROSS CNTRL TX IMMEDIATELY AHEAD OF SFC FRONT...AND FARTHER EAST ACROSS PORTIONS SRN AL/GA IN ASSOCIATION WITH NWD DRIFTING WARM FRONT. THIS LATTER FEATURE MAY NOT LOOSE ITS IDENTITY AS CONVECTION DEVELOPS ALONG/NORTH OF THE WIND SHIFT THROUGH THE PERIOD. LATEST THINKING IS MOISTURE/INSTABILITY WILL SURGE NWD ACROSS CNTRL/ERN TX OVER THE NEXT SEVERAL HOURS WHICH SHOULD RESULT IN STRONG/SEVERE THUNDERSTORM DEVELOPMENT BETWEEN 09-12Z. THIS ACTIVITY SHOULD SPREAD RAPIDLY NEWD AHEAD OF COLD FRONT INTO THE LOWER MS VALLEY BY 18Z. BY EARLY AFTERNOON IT APPEARS SIGNIFICANT BOUNDARY LAYER MOISTENING/HEATING WILL HAVE OCCURRED FROM NRN LA/SERN AR INTO WRN TN. FORECAST SOUNDINGS SUGGEST THIS REGION WILL BECOME QUITE SUPPORTIVE FOR STRONG SUPERCELL DEVELOPMENT AS SHEAR INCREASES ALONG WITH STEEPENING LAPSE RATES. ANY STORMS THAT EVOLVE AHEAD OF DEEPENING LOW WITHIN EXIT REGION OF UPPER JET WILL EASILY ROTATE AND IF 60F+ SFC DEW POINTS DO INDEED SPREAD INTO THIS REGION THEN TORNADOES CAN BE EXPECTED...SOME POTENTIALLY STRONG AND LONG TRACK. BETWEEN 18-00Z IT APPEARS THE GREATEST THREAT FOR TORNADIC SUPERCELLS WILL BE ACROSS NRN LA/SERN AR/MS INTO WRN AL/TN. DURING THE EVENING/OVERNIGHT HOURS...A CONCENTRATED ZONE OF SEVERE SHOULD SPREAD DOWNSTREAM AS LLJ LIFTS INTO THE OH VALLEY AND SFC LOW EJECTS INTO SRN IND. FARTHER SOUTHEAST...WEAK WARM FRONT WILL LIKELY REMAIN ANCHORED ACROSS SRN GA INTO SRN AL AS PERSISTENT CONVECTION DUE TO WARM ADVECTION MAINTAINS ELY COMPONENT AND COOLER BOUNDARY LAYER TEMPERATURES JUST SOUTH OF THE HIGHER TERRAIN. MARITIME TROPICAL AIRMASS IS SITUATED JUST SOUTH OF THIS BOUNDARY WITH 70F+ DEW POINTS LOCATED ACROSS THE FL PANHANDLE. THIS MOISTURE SHOULD CREEP NWWD INTO SRN AL PRIOR TO INFLUENCE OF UPPER TROUGH. EVEN SO...MID-HIGH LEVEL FLOW WITHIN SRN STREAM WILL INCREASE WITH TIME AND SHEAR PROFILES WILL BECOME QUITE STRONG ATOP AN INCREASINGLY UNSTABLE AIRMASS. IN FACT EMBEDDED IMPULSES WITHIN THIS FLOW MAY ACTIVATE ROBUST THUNDERSTORM DEVELOPMENT EARLY IN THE PERIOD. FORECAST SOUNDINGS ACROSS THIS REGION ARE IMPRESSIVE WITH SHEAR/INSTABILITY STRONGLY INDICATIVE OF SUPERCELLS CAPABLE OF GENERATING TORNADOES...SOME OF WHICH MAY BE STRONG. IT/S NOT ENTIRELY CLEAR HOW MUCH DESTABILIZATION WILL OCCUR FARTHER NORTH INTO NRN GA/SC WHERE CLOUDS/PRECIPITATION WILL LIMIT HEATING. DURING THE OVERNIGHT HOURS DESTABILIZATION IS POSSIBLE ALONG THE CAROLINA COAST. IF SUFFICIENT INSTABILITY CAN SPREAD INLAND THEN A RISK OF SEVERE SUPERCELLS/TORNADOES CAN BE EXPECTED...PRIMARY AFTER MIDNIGHT. ..DARROW/JEWELL.. 04/02/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z