SPC AC 180731
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0231 AM CDT SAT MAY 18 2013
   
   VALID 201200Z - 211200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...CNTRL PLAINS...MID MS VALLEY...UPPER MS VALLEY AND GREAT
   LAKES REGION...
   
   ...REGIONAL SEVERE WEATHER EPISODE POSSIBLE ACROSS PARTS OF THE SRN
   AND CNTRL PLAINS INTO THE OZARKS MONDAY AFTERNOON AND EVENING...
   
   ...SRN AND CNTRL PLAINS/OZARK PLATEAU...
   AN UPPER-LEVEL LOW WILL REMAIN IN PLACE ACROSS THE NRN AND CNTRL
   PLAINS ON MONDAY WITH SOUTHWEST FLOW LOCATED FROM THE SRN PLAINS
   INTO THE MID MS VALLEY. AT THE SFC...A LOW IS FORECAST TO MOVE NEWD
   ACROSS THE SRN PLAINS WITH DEWPOINTS SOUTH AND EAST OF THE LOW IN
   THE MID TO UPPER 60S F. A CAPPING INVERSION IN PLACE FOR MUCH OF THE
   DAY...SHOULD WEAKEN BY LATE AFTERNOON ALLOWING FOR ROBUST CONVECTIVE
   INITIATION. MODEL FORECASTS DEVELOP SEVERAL CLUSTERS OF
   THUNDERSTORMS LATE MONDAY AFTERNOON FROM THE SFC LOW NEAR THE RED
   RIVER NEWD INTO CNTRL AND ERN OK. THE MODELS APPEAR TO ORGANIZE AN
   MCS ACROSS THE SRN PLAINS AND MOVE THIS CONVECTIVE SYSTEM NEWD INTO
   THE OZARKS DURING THE EVENING.
   
   FORECAST SOUNDINGS IN SRN OK AND NEAR THE RED RIVER IN NORTH TX AT
   00Z/TUE SHOW IMPRESSIVE THERMODYNAMIC AND SHEAR PROFILES WITH MLCAPE
   VALUES OF 2500 TO 3500 J/KG AND 0-6 KM SHEAR VALUES OF 45 TO 55 KT.
   THIS ENVIRONMENT SHOULD BE FAVORABLE FOR SUPERCELLS WITH LARGE HAIL.
   HAILSTONES OF GREATER THAN 2 INCHES IN DIAMETER WILL BE POSSIBLE
   WITH THE MORE DOMINANT SUPERCELLS. IN ADDITION...LOW-LEVEL
   HODOGRAPHS ALSO LOOK IMPRESSIVE WITH 0-3 KM STORM RELATIVE
   HELICITIES IN THE 400 TO 50O M2/S2 RANGE BY EARLY MONDAY EVENING.
   THIS SUGGESTS TORNADIC SUPERCELLS WILL BE POSSIBLE WITH A POTENTIAL
   FOR STRONG TORNADOES. IF MESOSCALE CONDITIONS COME TOGETHER AS THE
   MODELS SUGGEST...THEN A CLUSTER OF TORNADOES COULD OCCUR ACROSS
   PARTS OF THE SRN PLAINS LATE MONDAY AFTERNOON INTO THE EVENING. WIND
   DAMAGE WILL ALSO BE POSSIBLE WITH SUPERCELLS AND BOWING
   LINE-SEGMENTS. THE MAIN CONCERN ABOUT FORECASTING A SIGNIFICANT
   EVENT THIS FAR OUT...IS THAT MULTIPLE DAYS OF THUNDERSTORMS BETWEEN
   NOW AND MONDAY WILL LIKELY ALTER THE OUTCOME AND THAT THE SCENARIO
   WILL BE DIFFERENT THAN WHAT IS CURRENTLY PRESENTED BY THE MODELS.
   
   ...MID TO UPPER MS VALLEY/GREAT LAKES...
   AN UPPER-LEVEL LOW IS FORECAST TO REMAIN IN PLACE ACROSS THE NRN AND
   CNTRL PLAINS ON MONDAY AS A SHORTWAVE TROUGH ROTATES AROUND THE ERN
   SIDE OF THE UPPER-LEVEL LOW. THE SHORTWAVE TROUGH AND AN ASSOCIATED
   MID-LEVEL JET WILL HELP FOCUS CONVECTIVE DEVELOPMENT ACROSS THE MID
   TO UPPER MS VALLEY AND GREAT LAKES REGION MONDAY AFTERNOON. SFC
   DEWPOINTS ARE FORECAST TO BE IN THE LOWER TO MID 60S F ACROSS A
   BROAD CORRIDOR FROM THE MID MS VALLEY EXTENDING NEWD INTO THE LOWER
   OH VALLEY WHERE THE MODELS DEVELOP MODERATE INSTABILITY BY
   AFTERNOON. THIS COMBINED WITH MODERATE DEEP LAYER SHEAR
   PROFILES...ENHANCED BY THE MID-LEVEL JET...SHOULD SUPPORT SEVERE
   THUNDERSTORM DEVELOPMENT. THE SEVERE THREAT SHOULD DEVELOP ACROSS A
   BROAD AREA WHERE MESOSCALE FEATURES AND THE MAGNITUDE OF INSTABILITY
   WILL BECOME IMPORTANT FOR SEVERE THREAT COVERAGE.  WIND DAMAGE AND
   LARGE HAIL APPEAR TO BE THE GREATEST THREATS AT THIS TIME BUT MUCH
   UNCERTAINTY EXISTS CONCERNING HOW THE EVENT WILL PLAY OUT.
   
   ..BROYLES.. 05/18/2013
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z