Tornado watch in South Central MS
SPC Text:
DISCUSSION...THE LOW-LEVELS CONTINUE TO DESTABILIZE ALONG AND S OF A COMPOSITE OUTFLOW BOUNDARY ACROSS CENTRAL MS...NEAR AND JUST N OF I-20. MLCAPE VALUES IN EXCESS OF 3000 J/KG ARE EXPECTED THIS AFTERNOON IN THE WARM SECTOR...WHILE THE CAP GRADUALLY WEAKENS. ADDITIONAL THUNDERSTORM DEVELOPMENT APPEARS LIKELY BY EARLY AFTERNOON ALONG THE OUTFLOW BOUNDARY...AND POTENTIALLY BY MID AFTERNOON IN THE WARM SECTOR IMMEDIATELY S OF THE BOUNDARY. DEEP LAYER VERTICAL SHEAR WILL BE SUFFICIENT FOR SUPERCELLS AND BOW ECHOES CAPABLE OF PRODUCING TORNADOES AND DAMAGING WINDS...AND VERY LARGE HAIL WILL BE POSSIBLE WITH THE MOST INTENSE STORMS. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 27030.
At 11:30a.m., The SPC moved the tornado and moderate risks southward and eastward.
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Latest Public Severe Weather Outlook Issued at 11:37 a.m.:
PUBLIC SEVERE WEATHER OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1137 AM CDT WED MAY 10 2006 ...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER MISSISSIPPI RIVER VALLEY AND MID SOUTH THIS AFTERNOON AND TONIGHT... THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE DEVELOPMENT OF WIDESPREAD SEVERE THUNDERSTORMS INCLUDING A FEW STRONG AND DAMAGING TORNADOES OVER PARTS OF THE LOWER MISSISSIPPI RIVER VALLEY AND MID SOUTH THIS AFTERNOON AND TONIGHT. THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE MUCH OF ALABAMA FAR SOUTHEASTERN ARKANSAS NORTHEASTERN LOUISIANA MUCH OF MISSISSIPPI SURROUNDING THE MODERATE RISK AREA...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TEXAS COAST EASTWARD ACROSS THE GULF COAST AND NORTHWARD INTO THE OHIO VALLEY AND SOUTHERN GREAT LAKES REGIONS. A RATHER VOLATILE SITUATION APPEARS TO BE TAKING SHAPE OVER MUCH THE LOWER MISSISSIPPI VALLEY THIS AFTERNOON WITH CONDITIONS BECOMING FAVORABLE FOR A SIGNIFICANT SEVERE THUNDERSTORM EPISODE. A BROAD TROUGH ALOFT WILL SPREAD VERY STRONG WESTERLY MID LEVEL WINDS ACROSS THE REGION. MEANWHILE AT THE SURFACE...A COLD FRONT WILL ADVANCE SOUTHEASTWARD INTO THE LOWER OHIO...LOWER MISSISSIPPI AND TENNESSEE RIVER VALLEYS THROUGH TONIGHT. ONGOING THUNDERSTORMS THIS MORNING OVER PORTIONS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS HAVE PRODUCED A COOLER AIR MASS IN THEIR WAKE ACROSS MOST OF EASTERN ARKANSAS...NORTHERN MISSISSIPPI AND NORTHERN AND CENTRAL ALABAMA. HOWEVER ABUNDANT GULF MOISTURE IS IN PLACE JUST UPSTREAM ACROSS LOUISIANA AND SOUTHERN MISSISSIPPI. THE PRESENCE OF THIS MOISTURE WILL SUPPORT VERY STRONG INSTABILITY AHEAD OF AN APPROACHING UPPER TROUGH AND SURFACE COLD FRONT...AND IT IS EXPECTED THAT ADDITIONAL RAPID SEVERE THUNDERSTORM DEVELOPMENT WILL OCCUR ACROSS MUCH OF THE LOWER MISSISSIPPI VALLEY AND PORTIONS OF THE MID SOUTH DURING THE AFTERNOON. STORMS WILL BECOME SUPERCELLS WITH AN ENHANCED THREAT OF TORNADOES AND VERY LARGE DAMAGING HAIL. THE TORNADO THREAT SHOULD BE GREATEST NEAR RESIDUAL SURFACE BOUNDARIES LEFT OVER FROM THE MORNING STORMS WITH CONDITIONS MOST FAVORABLE FOR A FEW STRONG AND DAMAGING TORNADOES LATER THIS AFTERNOON AND THIS EVENING. THE SEVERE THUNDERSTORM ACTIVITY WILL LIKELY EVOLVE INTO ONE OR MORE LARGE CLUSTERS THROUGH THE EVENING WITH THE SEVERE THREAT GRADUALLY TRANSITIONING TO PRIMARILY LARGE HAIL AND DAMAGING WINDS OVERNIGHT. THOSE IN THE THREATENED AREA ARE URGED TO REVIEW SEVERE WEATHER SAFETY RULES AND TO LISTEN TO RADIO...TELEVISION...AND NOAA WEATHER RADIO FOR POSSIBLE WATCHES...WARNINGS...AND STATEMENTS LATER TODAY. ..CROSBIE/IMY.. 05/10/2006
Severe Thunderstorm Watch Until 3PM
URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 330 NWS STORM PREDICTION CENTER NORMAN OK 950 AM CDT WED MAY 10 2006 THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF WEST CENTRAL AND NORTHWEST ALABAMA CENTRAL AND NORTHEAST MISSISSIPPI EFFECTIVE THIS WEDNESDAY MORNING AND AFTERNOON FROM 950 AM UNTIL 300 PM CDT. HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE MILES EITHER SIDE OF A LINE FROM 50 MILES WEST SOUTHWEST OF TUPELO MISSISSIPPI TO 20 MILES EAST OF TUSCALOOSA ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0). REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. OTHER WATCH INFORMATION...CONTINUE...WW 328...WW 329... DISCUSSION...LINEAR MCS ACROSS NRN MS WILL LIKELY PERSIST INTO THE EARLY AFTERNOON AS MOISTURE/INSTABILITY FEEDS NEWD OVER A NW-SE ORIENTED OUTFLOW BOUNDARY ACROSS CENTRAL MS. THOUGH THE CONVECTION IS BASED ABOVE THE GROUND RIGHT NOW...THE LOW LEVELS MAY GRADUALLY DESTABILIZE AND SUPPORT A THREAT FOR DAMAGING WINDS AND LARGE HAIL WITH THE STRONGER STORMS. LATER THIS AFTERNOON...THE REGION NEAR THE OUTFLOW BOUNDARY FROM THIS CONVECTION...AND THE EARLIER STORMS IN AL...WILL BE MONITORED FOR AN INCREASING TORNADO THREAT.
SPC Tornado Outlook
SPC Severe Weather Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0730 AM CDT WED MAY 10 2006 VALID 101300Z - 111200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM LA/MS INTO SWRN KY... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK FROM THE UPPER TX COAST INTO THE OH VALLEY... ...TORNADOES...A FEW STRONG ARE POSSIBLE ACROSS PORTIONS OF THE GULF STATES INTO THE TN VALLEY... A SIGNIFICANT SEVERE WEATHER EVENT IS EXPECTED TO EVOLVE ACROSS THE LOWER MS VALLEY AND CNTRL GULF STATES...NWD ACROSS PORTIONS OF THE TN VALLEY TODAY. TORNADOES...POTENTIALLY STRONG...DAMAGING WINDS AND VERY LARGE HAIL ARE ALSO POSSIBLE PRIOR TO COLD FRONTAL PASSAGE. THREE MCS CLUSTERS ARE ONGOING EARLY THIS MORNING FROM THE RED RIVER REGION OF SRN OK/NCNTRL TX...EAST ACROSS AR...AND ANOTHER INTO CNTRL AL. THIS EARLY ACTIVITY WILL PLAY AN IMPORTANT ROLE IN FUTURE DEVELOPMENT/STORM MODE AS BOUNDARY LAYER WARMS TO THE SOUTH OF CONVECTIVE OUTFLOWS. OVERNIGHT TRENDS REMAIN SUPPORTIVE OF EARLIER OUTLOOK...ALTHOUGH CONFIDENCE IN TORNADIC SUPERCELLS HAS RISEN ACROSS MS INTO NRN AL. THIS ZONE OF HEIGHTENED INTEREST IS PARTIALLY DUE TO THE INFLUENCE OF OVERNIGHT MCS THAT HAS BACKED LOW LEVEL FLOW TO THE NORTH OF ASSOCIATED OUTFLOW BOUNDARY. THIS WILL MAINTAIN HIGH HELICITY ENVIRONMENT WITHIN STRONGEST ZONE OF LOW LEVEL WARM ADVECTION WHERE SUPERCELL THUNDERSTORM DEVELOPMENT IS EXPECTED BY EARLY AFTERNOON. THERE IS SOME CONCERN THAT AFOREMENTIONED MCS CLUSTERS COULD HINDER DISCRETE DEVELOPMENT ACROSS FAR NRN PORTIONS OF MODERATE RISK...HOWEVER SIGNIFICANT CAP ACROSS SERN TX/LA WILL PREVENT SWD DEVELOPMENT THROUGH MID-LATE MORNING. AS A RESULT...VERY UNSTABLE AIR MASS WILL SPREAD NEWD...RETURNING ATOP STRONGLY SHEARED BUT LESS CAPPED REGION OF THE NCNTRL GULF STATES. CURRENT THINKING IS STRONGEST FORCED CONVECTION ALONG COLD FRONT WILL MAINTAIN N-S LINEAR STRUCTURE AS IT ADVANCES EWD ALONG THE RED RIVER OF SRN OK/NERN TX. THIS ACTIVITY SHOULD GRADUALLY EXPAND IN AREAL COVERAGE...POSSIBLY OVERTAKING DOWNSTREAM CONVECTION OVER AR BY MID-LATE MORNING. AN EVER EXPANDING MCS MAY EVOLVE FROM THIS INTERACTION WITH NEWD DEVELOPMENT INTO THE WRN PORTIONS OF THE TN VALLEY AS SFC LOW LIFTS NEWD. DOWNSTREAM...BOUNDARY LAYER HEATING/MOISTENING ATOP MODIFYING OUTFLOW AIR MASS OVER MS/AL SHOULD ALLOW FOR MORE DISCRETE SUPERCELL STRUCTURES TO DEVELOP. FORECAST SOUNDINGS FOR THIS REGION...PARTICULARLY FROM THE 09Z RUC...STRONGLY FAVOR TORNADIC DEVELOPMENT AS CELL MOTION UTILIZES HIGHER HELICITY ENVIRONMENT. OTHER STORMS WILL ALSO DEVELOP ACROSS THE WARM SECTOR AHEAD OF THE COLD FRONT AS IT ADVANCES EWD INTO LA. VERY STEEP LAPSE RATES AND EXTREME SBCAPE...IN EXCESS OF 5000 J/KG...WILL AID IN VERY LARGE HAIL DEVELOPMENT...AS WELL AS ENHANCE DAMAGING WIND POTENTIAL. MULTIPLE STORM MODES APPEAR LIKELY ACROSS THE MODERATE RISK REGION...WITH WIDESPREAD SEVERE CONSISTING OF TORNADOES...DAMAGING HAIL...AND INTENSE WIND. FRONTAL PASSAGE LATE TONIGHT WILL END SEVERE THREAT FROM WEST TO EAST. ..DARROW/LEVIT.. 05/10/2006
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