SPC AC 221728
   
   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1228 PM CDT WED MAY 22 2013
   
   VALID 231200Z - 241200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER NWRN TX AND WRN OK...
   
   ...SYNOPSIS...
   UPPER LOW OVER THE UPPER MS VALLEY IS FORECAST TO MOVE EWD AND
   WEAKEN TOMORROW AS IT SHEARS NEWD IMMEDIATELY IN ADVANCE OF A SHORT
   WAVE TROUGH DIGGING SEWD ACROSS THE GREAT LAKES AND OHIO VALLEY.  IN
   THE WEST...AN UPPER LOW OVER THE PACIFIC NW IS EXPECTED TO REMAIN
   ACROSS THE REGION WHILE AN UPPER RIDGE AMPLIFIES OVER THE PLAINS
   STATES.  AT THE SURFACE...A LOW IN THE ST. LAWRENCE VALLEY IS
   EXPECTED TO LIFT SLOWLY NEWD...AS A TRAILING COLD FRONT MOVES SEWD
   FROM THE LOWER GREAT LAKES/OH VALLEY/MID-SOUTH EARLY IN THE PERIOD
   REACHING THE ATLANTIC COAST AND NRN GULF COAST BY 24/12Z.  THE WRN
   PORTION OF THE FRONT WILL EXTEND NWWD INTO NWRN TX AND THE ROCKIES.
   
   ...NWRN TX/WRN OK...
   A FEW ELEVATED THUNDERSTORMS MAY BE ONGOING EARLY IN THE PERIOD OVER
   PARTS OF OK TO THE NORTH OF THE AFOREMENTIONED FRONTAL BOUNDARY
   EXTENDING ACROSS NWRN TX.  ASSOCIATED CLOUDS/PRECIPITATION MAY DELAY
   STRONGER DIABATIC HEATING TO THE NORTH OF THE FRONT RESULTING IN AN
   ENHANCEMENT OF THE THERMAL GRADIENT ATTENDING THE FRONT DURING THE
   AFTERNOON.  WITH SURFACE DEW POINTS IN THE 60S ALONG AND NORTH OF
   THE FRONT OVERLAID BY STEEP MID LEVEL LAPSE RATES ASSOCIATED WITH AN
   ELEVATED MIXED LAYER...THE ENVIRONMENT IS LIKELY TO BECOME VERY
   UNSTABLE WITH MLCAPE REACHING 3000-3500 J/KG.  ALTHOUGH DYNAMIC
   FORCING FOR LARGE SCALE ASCENT WILL BE MINIMAL WITHIN THE UPPER
   RIDGE...LOW LEVEL CONVERGENCE/WARM ADVECTION ALONG AND NORTH OF THE
   FRONT COUPLED WITH STRONG HEATING SHOULD WEAKEN THE CAP SUFFICIENTLY
   FOR WIDELY SCATTERED STORMS TO DEVELOP DURING THE MID/LATE
   AFTERNOON.  DESPITE MODEST WINDS ALOFT /25 KT AT 500 MB/...STRONG
   DIRECTIONAL SHEAR WITH HEIGHT WILL ENHANCE STORM ORGANIZATION WITH
   POTENTIAL FOR A FEW SUPERCELLS TO DEVELOP.  STRONGER CELLS WILL BE
   CAPABLE OF PRODUCING VERY LARGE HAIL AND DAMAGING WIND GUSTS...WITH
   THE LATTER THREAT INCREASING IF STORMS CAN GROW UPSCALE INTO A SMALL
   MCS AND MOVE EWD/SEWD DURING THE EVENING.  THERE WILL ALSO BE
   POTENTIAL FOR A TORNADO OR TWO TO DEVELOP ESPECIALLY DURING THE
   INITIAL PHASE OF SUPERCELL DEVELOPMENT.  ACTIVITY IS EXPECTED TO
   DIMINISH IN INTENSITY AFTER 03-06Z.
   
   ...NEW ENGLAND SWD INTO ERN NC...
   MODEL GUIDANCE SUGGESTS THAT CLOUDS AND AREAS OF PRECIPITATION WILL
   BE WIDESPREAD AHEAD OF THE COLD FRONT TOMORROW WHICH WILL LIMIT THE
   MAGNITUDE OF DIABATIC HEATING AND DESTABILIZATION ACROSS MUCH OF THE
   AREA...WITH MLCAPE GENERALLY AOB 1000 J/KG.  THERE IS ANTICIPATION
   THAT SOME BREAKS IN THE CLOUD COVER WILL PERMIT LOCALIZED REGIONS TO
   UNDERGO GREATER DESTABILIZATION...BUT THESE AREAS ARE DIFFICULT TO
   IDENTIFY ATTM.  AS STRONGER SWLY WINDS ALOFT OVERSPREAD THE
   PRE-FRONTAL ENVIRONMENT DURING THE DAY...THERE WILL BE POTENTIAL FOR
   A FEW STRONGER STORMS TO DEVELOP.  HOWEVER...OWING TO CONCERNS ABOUT
   THE EFFECTS OF CLOUDS AND ONGOING CONVECTION ON AIR MASS
   STABILITY...WILL MAINTAIN THE CURRENT 5% SEVERE PROBABILITY CORRIDOR
   FROM ERN NC INTO NEW ENGLAND.  IF IT BECOMES EVIDENT TOMORROW THAT
   ZONES OF MORE PRONOUNCED DESTABILIZATION WILL OCCUR...PORTIONS OF
   THE AREA MAY REQUIRE AN UPGRADE TO SLIGHT RISK.
   
   ..WEISS.. 05/22/2013
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z