Day 2 Convective Outlook

SPC AC 071735
  
   DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1135 AM CST MON MAR 07 2011
  
   VALID 081200Z - 091200Z
  
   ...THERE IS A SLGT RISK OF SVR TSTMS FOR ERN PARTS OF THE SRN PLAINS
   TO THE LOWER/MID MS VALLEY...
  
   ...SYNOPSIS...
   PROGRESSIVE UPPER-LEVEL SHORTWAVE TROUGH DIGGING SEWD OVER THE SWRN
   CONUS MONDAY MORNING WILL MOVE DOWNSTREAM ACROSS THE SRN PLAINS
   DURING TUE AFTERNOON...ACCOMPANIED BY STRONG 70 KT MIDLEVEL
   JET...AND THEN EJECT NEWD INTO THE MID MS VALLEY BY 09/12Z. AS THIS
   OCCURS...SURFACE LOW IS FORECAST TO PROGRESS ACROSS OK THROUGH TUE
   AFTERNOON...AND THEN MOVE NEWD ACROSS MO DURING THE OVERNIGHT HRS. A
   MODIFIED CP AIRMASS WILL BE DRAWN NWD IN RESPONSE TO THE SURFACE
   CYCLONE...BOUNDED BY A DRYLINE TRAILING SWD ACROSS TX...AND A
   RETREATING WARM FRONT...WHICH IS FORECAST TO RAPIDLY LIFT NWD INTO
   SRN AR BY 09/00Z.
  
   ...AR DURING THE MORNING AND AFTERNOON...
   AS THE LOW-LEVEL CYCLONE ATTENDANT TO THE UPPER TROUGH EMERGES OVER
   THE SRN PLAINS...40-50 KT SLY 850 MB JET WILL DEVELOP OVER THE LWR
   MS VALLEY BY LATE MORNING. THIS WILL RESULT IN ROBUST LOW-LEVEL
   WAA/MOISTURE ADVECTION ABOVE A STABLE BOUNDARY LAYER
   AIRMASS...AIDING IN DESTABILIZATION AND MUCAPE VALUES NEAR 500 J/KG
   ACROSS AR AS MIDLEVEL LAPSE RATES STEEPEN TO 7.0-7.5 C/KM. GIVEN
   SWLY 500 MB FLOW INCREASING TO 60 KT COMBINED WITH DEEPENING FREE
   CONVECTIVE LAYER...EFFECTIVE BULK SHEAR VALUES NEAR 40 KT APPEAR
   PROBABLE...WHICH MAY SUPPORT MARGINALLY SVR HAIL ACROSS AR THROUGH
   MID AFTERNOON.
  
   ...ERN OK/NERN TX EWD TO OZARKS/MID SOUTH...
   FARTHER W...NARROW WEDGE OF MID TO UPR 50S DEWPOINTS ARE FORECAST TO
   ADVECT NWD BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES OVER
   CNTRL/ERN OK BY MID TO LATE AFTERNOON. MEANWHILE...A ZONE OF STEEP
   LOW-LEVEL LAPSE RATES WILL DEVELOP NEWD ACROSS SWRN OK BEHIND THE
   DRYLINE AND AHEAD OF A COLD FRONT OVER W-CNTRL AND N-CNTRL OK. THIS
   SHOULD PROVE SUFFICIENT FOR THE DEVELOPMENT OF A CORRIDOR OF MLCAPE
   VALUES FROM 500-1000 J/KG. STRONGEST LOW-LEVEL CONVERGENCE IS
   EXPECTED FROM THE TRIPLE POINT N-NEWD ALONG THE COLD FRONT OVER
   N-CNTRL/NERN OK...WHICH WILL AID IN THUNDERSTORM INITIATION DURING
   THE AFTERNOON. DUE TO AN INCREASINGLY NARROW ZONE OF INSTABILITY
   WITH NWD EXTENT...STORMS MAY STRUGGLE TO PERSIST N OF I-40.
   HOWEVER...A STRONGLY SHEARED ENVIRONMENT JUXTAPOSED WITH STEEP
   MIDLEVEL LAPSE RATES MAY FAVOR A FEW SVR STORMS PRODUCING LARGE HAIL
   AND DAMAGING WIND GUSTS.
  
   FARTHER S ALONG THE DRYLINE OVER SERN OK/NERN TX...FORCING FOR
   ASCENT WILL BE WEAKER...WHICH MAY DELAY INITIATION UNTIL LATE
   AFTERNOON. THE POTENTIAL FOR AN INITIALLY DISCRETE CONVECTIVE
   MODE...COMBINED WITH INCREASING DOWNSTREAM DESTABILIZATION...WILL
   FAVOR LONGER-LIVED STORMS...LIKELY SUPERCELLS GIVEN STRONG DEEP
   LAYER SHEAR /0-6 KM BULK SHEAR AOA 60 KT/ SPREADING ACROSS THE
   DRYLINE. THIS ACTIVITY SHOULD MOVE QUICKLY E-NEWD INTO AN EXPANDING
   WARM SECTOR OVER NRN LA AND SRN AR...AND WILL POSE A THREAT FOR
   LARGE HAIL/DAMAGING WINDS AND TORNADOES.
  
   THE FORECAST POSITION OF THE WARM FRONT IS NOT CERTAIN ATTM DUE TO
   THE POTENTIAL FOR PERSISTENT CONVECTION AND SUBSEQUENT COLD POOL
   REINFORCEMENT. HOWEVER...ADDITIONAL STORM DEVELOPMENT WILL BE
   POSSIBLE ALONG THE BOUNDARY OVER AR GIVEN A FAVORABLE ORIENTATION OF
   THE LLJ ACROSS THE FRONT...AIDING IN MESOSCALE ASCENT. LOW-LEVEL
   VERTICAL WIND SHEAR WILL BE QUITE STRONG /EFFECTIVE SRH VALUES IN
   EXCESS OF 300 M2 S-2/ OVER SRN AR/NRN LA...AND WILL FAVOR A FEW
   TORNADIC STORMS /POSSIBLY PRODUCING STRONG TORNADOES/ ASSOCIATED
   WITH EITHER THE ACTIVITY MOVING OUT OF SERN OK/NERN TX...OR NEW
   DEVELOPMENT INVOF THE WARM FRONT. OVERNIGHT...THE UPPER TROUGH AND
   SURFACE COLD FRONT WILL PROGRESS ACROSS AR AND SRN MO. INCREASING
   LINEAR FORCING FOR ASCENT WILL FAVOR A TRANSITION TO A QUASI-LINEAR
   CONVECTIVE MODE...POSING A CONTINUED THREAT FOR DAMAGING WINDS AND
   TORNADOES.
  
   ...E TX AND LOWER MS VALLEY...
   FARTHER S OVER ERN TX...THUNDERSTORM INITIATION IS SOMEWHAT IN
   QUESTION GIVEN A PERSISTENT CAP NOTED IN MODEL FORECAST SOUNDINGS.
   HOWEVER...IF A FEW STORMS MANAGE TO DEVELOP...THE POTENTIAL WILL
   EXIST FOR DAMAGING WINDS AND LARGE HAIL. OVER LA/MS...STRONG UPPER
   DIVERGENCE/LARGE-SCALE ASCENT IS FORECAST TO DEVELOP FROM SRN LA
   ACROSS SWRN MS. THUNDERSTORMS ARE EXPECTED TO FORM WITHIN THIS
   REGIME BY LATE AFTERNOON THROUGH THE NIGHT...FOCUSED ALONG AND AHEAD
   OF A SW-NE ORIENTED LOW-LEVEL CONVERGENCE ZONE...AS WELL AS ALONG
   THE SRN EXTENSION OF THE WARM FRONT. A VERY MOIST BOUNDARY LAYER
   /SURFACE DEWPOINTS IN THE MID 60S/ AND MODERATELY STEEP MIDLEVEL
   LAPSE RATES WILL SUPPORT MLCAPE VALUES AROUND 1000 J/KG. IN
   ADDITION...STRONG VERTICAL WIND SHEAR PROFILES WILL BE IN
   PLACE...WITH EFFECTIVE SRH NEAR 400 M2 S-2 /PARTICULARLY NEAR THE
   WARM FRONT/. THE STRONGLY SHEARED AND MOIST ENVIRONMENT WILL FAVOR
   SUPERCELLS POSING A THREAT FOR TORNADOES /POSSIBLY SIGNIFICANT/ AND
   DAMAGING WINDS.
  
   ..GARNER/EDWARDS.. 03/07/2011