SPC AC 251249

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0749 AM CDT WED MAY 25 2016

   VALID 251300Z - 261200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR SW TX THIS AFTERNOON
   THROUGH TONIGHT...

   ...THERE IS A MRGL RISK OF SVR TSTMS TODAY FOR MUCH OF THE PLAINS
   AND MIDWEST...

   ...SUMMARY...
   ISOLATED STRONG/SEVERE STORMS WITH HAIL AND DAMAGING WIND GUSTS WILL
   BE POSSIBLE THIS AFTERNOON AND TONIGHT ACROSS SOUTHWEST TEXAS.  A
   LESS CERTAIN AND/OR MORE MARGINAL SEVERE STORM RISK COVERS A BROAD
   AREA OF THE PLAINS AND MIDWEST.

   ...SW TX LATE TODAY INTO TONIGHT...
   A MIDLEVEL SHORTWAVE TROUGH APPROACHING SRN CA THIS MORNING WILL
   PROGRESS EWD TO AZ/NM TONIGHT.  A VERY MOIST BUT CAPPED BOUNDARY
   LAYER IS PRESENT ACROSS SW TX...AND DRYLINE STORM INITIATION IS
   UNCERTAIN THIS AFTERNOON.  HOWEVER...CONTINUED MOISTENING AND A
   GLANCING INFLUENCE OF THE AZ/NM TROUGH...OR ANY PRECEDING
   SUBTROPICAL SPEED MAXIMA...COULD SUPPORT NOCTURNAL THUNDERSTORM
   DEVELOPMENT.  LARGE HAIL AND STRONG/DAMAGING GUSTS WILL BE POSSIBLE
   WITH ANY STORMS THAT FORM EITHER THIS AFTERNOON OR OVERNIGHT...GIVEN
   THE STRONG BUOYANCY.

   ...PLAINS/MIDWEST THROUGH TONIGHT...
   AN INITIAL SHORTWAVE TROUGH OVER THE MID MO VALLEY THIS MORNING WILL
   EJECT NEWD TO THE UPPER MS VALLEY THIS AFTERNOON...AS AN ASSOCIATED
   WEAK SURFACE LOW MOVES FROM SE SD TO THE ND/MN BORDER.  SEVERAL
   CONVECTIVE BANDS/CLUSTERS ACCOMPANYING THIS SHORTWAVE TROUGH WILL
   MOVE ACROSS AREAS FROM MN TO AR TODAY.  THE ENVIRONMENT DOWNSTREAM
   FROM THE ONGOING STORMS IS ONLY WEAKLY UNSTABLE FROM MO NWD TO
   IA/MN...AND ANY RISK FOR DAMAGING WINDS/HAIL SHOULD REMAIN MARGINAL
   WITH THIS CONVECTION.  SOME FORM OF THE ONGOING NE OK AND WRN AR
   CONVECTION MAY PERSIST INTO THE DAY...AS THIS AREA LIES ON THE NERN
   GRADIENT OF THE RICHEST MOISTURE/BUOYANCY ACROSS OK/TX...WHERE THE
   CAP IS WEAKEST.  A FEW DAMAGING GUSTS AND SOME HAIL WILL BE
   POSSIBLE.

   THE POTENTIAL FOR THUNDERSTORMS IN THE WAKE OF THE MORNING
   CONVECTION IS HIGHLY UNCERTAIN FROM KS TO TX.  THE MORNING OUTFLOW
   BOUNDARIES ACROSS OK/KS SHOULD GRADUALLY BECOME MORE DIFFUSE BY
   EARLY AFTERNOON AS THE CONVECTION RESPONSIBLE FOR THE COLD POOLS
   DIMINISHES AND/OR MOVES WELL OFF TO THE E AND SE.  A DRYLINE WILL
   MIX EWD TO CENTRAL KS AND WRN OK/NW TX AND WILL DEMARCATE WRN EXTENT
   OF THE STRONGLY UNSTABLE WARM SECTOR...WHERE MLCAPE MAY EXCEED 4000
   J/KG.  HOWEVER...OTHER THAN RELATIVELY WEAK/SHALLOW DRYLINE
   CIRCULATIONS...THERE WILL BE LITTLE FORCING FOR ASCENT AND SOME
   LINGERING CONVECTIVE INHIBITION.  THE EXTREME BUOYANCY AND
   SUFFICIENT DEEP-LAYER VERTICAL SHEAR WILL FAVOR A CONDITIONAL RISK
   FOR ISOLATED SUPERCELLS WITH LARGE HAIL...BUT THE UNCERTAINTY
   REGARDING STORM INITIATION/COVERAGE PRECLUDES MORE THAN LOW SEVERE
   PROBABILITIES.

   FARTHER N...LOW-LEVEL AIR MASS RECOVERY WILL BE NECESSARY ALONG A
   DIFFUSE BAROCLINIC ZONE ACROSS NEB FOR ANY RENEWED SEVERE STORM
   THREAT...IN THE WAKE OF MULTIPLE OUTFLOWS FROM OVERNIGHT CONVECTION.
    A SUBTLE SPEED MAX WILL EJECT NEWD FROM CO TO NEB THIS
   AFTERNOON...AND THIS COULD HELP SUPPORT STORM DEVELOPMENT ACROSS SW
   AND CENTRAL NEB THIS AFTERNOON/EVENING IF BOUNDARY LAYER
   WARMING/MOISTENING IS SUFFICIENT.  BUOYANCY WILL BE WEAKER THAN
   AREAS FARTHER S IN KS...THOUGH DEEP-LAYER VERTICAL SHEAR WILL BE
   FAVORABLE FOR ORGANIZED STORMS CAPABLE OF PRODUCING ISOLATED LARGE
   HAIL AND DAMAGING WINDS. 

   INSTEAD OF MAINTAINING A LARGE SLGT RISK AREA WITH POTENTIALLY LARGE
   SWATHS WITH NO SEVERE THUNDERSTORM DEVELOPMENT...WILL KEEP LOWER
   HAIL/WIND PROBABILITIES TO REFLECT THE CONDITIONAL NATURE OF THE
   RISK ACROSS THE PLAINS/MIDWEST.  REINTRODUCTION OF SLGT RISK
   PROBABILITIES WILL BE POSSIBLE IN A FRACTION OF THE ORIGINAL OUTLOOK
   AREA...BUT ANY SUCH ADDITIONS WILL NECESSARILY BE DRIVEN BY
   MESOSCALE TRENDS DURING THE DAY.

   ..THOMPSON/COHEN.. 05/25/2016

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