SPC AC 081730
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1130 AM CST WED MAR 08 2006
   
   VALID 091200Z - 101200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER TO MID
   MS VALLEY...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...OZARKS...OH VALLEY AND TN VALLEY...
   
   ...MS VALLEY...
   AN IMPRESSIVE UPPER-LEVEL TROUGH OVER THE DESERT SW WILL EJECT EWD
   TONIGHT DEEPENING AND BECOMING NEGATIVELY TILTED OVER THE SRN PLAINS
   THURSDAY. AHEAD OF THIS POTENT UPPER-TROUGH LARGE-SCALE ASCENT WILL
   BECOME INCREASINGLY FOCUSED AS A 100 KT MID-LEVEL JET PUNCHES INTO
   THE LOWER MS VALLEY. RICH LOW-LEVEL MOISTURE AHEAD OF THE SYSTEM
   COMBINED WITH VERY STRONG WIND SHEAR PROFILES SUGGEST THE POTENTIAL
   FOR A MAJOR SEVERE WEATHER OUTBREAK EXISTS FOR THURSDAY AND THURSDAY
   NIGHT ACROSS THE LOWER TO MID MS VALLEY.
   
   A LARGE COMPLEX OF THUNDERSTORMS WILL LIKELY BE ONGOING AT THE
   BEGINNING OF THE PERIOD AS THE TROUGH SWINGS EWD INTO THE SRN
   PLAINS. AT 12Z MODEL CONSENSUS PLACES A SQUALL-LINE OR BROKEN LINE
   OF STORMS ALONG THE WEST EDGE OF A WELL-DEVELOPED LOW-LEVEL JET WITH
   THE LINE EXTENDING SWWD FROM THE LOWER OH VALLEY ACROSS THE OZARKS
   INTO THE SRN PLAINS. AHEAD OF THE UPPER-LEVEL TROUGH THE STRONG
   LOW-LEVEL FLOW SHOULD TRANSPORT SFC DEWPOINTS IN THE 60S F AS FAR
   NORTH AS SRN IL DURING THE DAY. THIS COMBINED WITH THE PROGRESSIVE
   AND VERY WELL-DEVELOPED NATURE OF THE UPPER-TROUGH SUGGESTS THAT
   INSTABILITY WILL BE SUFFICIENT FOR SEVERE STORMS. IN ADDITION...THE
   15Z TO 18Z FORECAST SOUNDINGS ACROSS THE REGION ON THURSDAY SHOW
   IMPRESSIVE SHEAR PROFILES WITH STRONG LOW TO MID-LEVEL VEERING AND
   SUFFICIENT SPEED SHEAR FOR SUPERCELLS WITH WELL-DEVELOP LOW-LEVEL
   MESOCYCLONES.
   
   ALTHOUGH NOT YET CERTAIN...A TORNADO OUTBREAK WILL BE POSSIBLE
   ESPECIALLY IF A LARGE NUMBER OF STORMS REMAIN DISCRETE AS THE
   INITIAL LARGE CLUSTER OF STORMS DRIFTS EWD AND EXPANDS FROM NORTH TO
   SOUTH ACROSS THE MS VALLEY DURING THE AFTERNOON. THE BEST POTENTIAL
   FOR LONG TRACK STRONG OR VIOLENT TORNADOES SHOULD BE WHERE
   INSTABILITY IS LOCALLY MAXIMIZED AND JUST AHEAD OF THE SFC LOW AND
   IN THE NOSE OF THE MID-LEVEL JET. IF THE MAJORITY OF THE STORMS
   REMAIN LINEAR INSTEAD OF DISCRETE...A WIDESPREAD WIND DAMAGE EVENT
   WOULD BE MORE LIKELY AS A SQUALL-LINE MOVES EWD ACROSS THE REGION.
   WIND GUSTS ABOVE 70 KTS AND LARGE HAIL ABOVE 2 INCHES WOULD BE
   POSSIBLE WITH THE SUPERCELLS AND BOW ECHOES EMBEDDED IN OR AHEAD OF
   THE LINE. THE HEAVIEST CONCENTRATION OF SEVERE WEATHER EVENTS SHOULD
   BE ALONG THE MOIST AXIS ACROSS AR...LA...MS AND WRN TN ALTHOUGH SOME
   SEVERE WEATHER WILL BE POSSIBLE AS FAR NORTH AS THE OH VALLEY AND
   SRN LOWER MI DUE TO THE STRONG MID-LEVEL FLOW AS THE LEFT EXIT
   REGION OF THE MID-LEVEL JET PASSES ACROSS THE REGION THURSDAY NIGHT.
   DURING THE NIGHT...A SOLID LINE SHOULD DRIFT EWD ACROSS THE OH AND
   TN VALLEYS WITH THE SEVERE WEATHER THREAT GRADUALLY DECREASING.
   
   ...WEST COAST...
   MODEL FORECASTS DEVELOP AN UPPER-LEVEL TROUGH ALONG THE WEST COAST
   THURSDAY SPREADING STRONG LARGE-SCALE ASCENT INTO WA...ORE AND CA
   THURSDAY NIGHT. AS THIS OCCURS...STEEP MID-LEVEL LAPSE RATES
   ASSOCIATED WITH THE TROUGH MAY BE ENOUGH FOR SCATTERED THUNDERSTORM
   DEVELOPMENT ALONG THE IMMEDIATE COASTAL AREAS. HOWEVER...INSTABILITY
   AND SHEAR IS NOT EXPECTED TO BE STRONG ENOUGH FOR AN OUTLOOK AREA OF
   SEVERE WEATHER THURSDAY NIGHT.
   
   ..BROYLES.. 03/08/2006
   
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