SPC AC 200549

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1249 AM CDT THU JUN 20 2013

   VALID 211200Z - 221200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE NRN/CNTRL
   PLAINS TO THE UPPER MS VALLEY...

   ...SYNOPSIS...
   AN UPPER-LEVEL TROUGH SHOULD DAMPEN SLIGHTLY AS IT SLOWLY SHIFTS EWD
   OVER THE NORTHWEST...WITH EMBEDDED IMPULSES ROTATING THROUGHOUT IT.
   A DOWNSTREAM MID-LEVEL ANTICYCLONE SHOULD REMAIN ANCHORED OVER THE
   SRN PLAINS WITH A RIDGE EMANATING NWD INTO THE UPPER MS VALLEY. A
   BELT OF MODERATE MID-LEVEL W/SWLYS WILL PERSIST ACROSS THE NRN
   PLAINS...WHICH MAY BE ENHANCED BY CONVECTIVELY-INDUCED IMPULSES. AT
   THE SURFACE...A LEE THERMAL LOW SHOULD BE CENTERED OVER NERN CO FRI
   AFTERNOON...WITH A SW/NE-ORIENTED SURFACE FRONT EXTENDING INTO THE
   UPPER MIDWEST. THIS FRONT AND WARM SECTOR OUTFLOW BOUNDARIES SHOULD
   BE MODULATED BY PROBABLE MCS/S ON D1.

   ...NRN/CNTRL PLAINS TO THE UPPER MS VALLEY...
   THE REMNANTS OF D1 MCS/S SHOULD BE ONGOING OVER PARTS OF THE UPPER
   MS VALLEY WITHIN A LOW-LEVEL WAA REGIME...ALONG THE LEADING EDGE OF
   THE PLAINS EML. SOME OF THIS ACTIVITY MAY PERSIST EWD DURING THE
   DIURNAL HEATING CYCLE WITH A RISK FOR ISOLATED SEVERE HAIL/WIND AS
   CAPPING STRENGTHENS WITH SRN EXTENT.

   FARTHER W...THE NAM DEPICTS HIGH PLAINS CONVECTION FORMING FRI
   MORNING AND RAPIDLY REMOVING THE CAP...GROWING UPSCALE THROUGH THE
   DAY. GIVEN ITS CONTINUED FASTER PROGRESSION OF THE NWRN CONUS
   TROUGH...THIS APPEARS TO BE AN OUTLIER. A MORE PLAUSIBLE SCENARIO IS
   FOR A RESERVOIR OF STRONG TO EXTREME INSTABILITY TO DEVELOP FRI
   AFTERNOON ALONG AND S OF THE AFOREMENTIONED SURFACE FRONT WITHIN A
   PLUME OF VERY STEEP MID-LEVEL LAPSE RATES AND ENRICHING LOW-LEVEL
   MOISTURE BENEATH A CAPPING INVERSION. LOW-LEVEL UPSLOPE FLOW TO THE
   N OF THE BOUNDARY AND GLANCING INFLUENCES OF SHORTWAVE IMPULSES
   ROTATING ACROSS THE NRN HIGH PLAINS SHOULD AID IN AFTERNOON TSTM
   INITIATION NEAR THE HIGHER TERRAIN INVOF BLACK HILLS. WITH STRONG
   EFFECTIVE SHEAR...ACTIVITY SHOULD MATURE INTO SUPERCELLS CAPABLE OF
   PRODUCING VERY LARGE HAIL AND A FEW TORNADOES.

   AS THE LLJ STRENGTHENS OVER THE CNTRL PLAINS/MID-MO
   VALLEY FRI EVENING...ADDITIONAL TSTMS WILL PROBABLY FORM EWD ALONG
   THE FRONT/REMNANT OUTFLOWS...A SCENARIO SUPPORTED BY THE GFS/ECMWF.
   CONSOLIDATING COLD POOLS MAY YIELD UPSCALE GROWTH INTO ONE OR MORE
   LONG-LIVED MCS/S. GIVEN THE DEGREE OF INSTABILITY ALONG WITH
   SUFFICIENT DEEP-LAYER SHEAR ON THE COOL SIDE OF THE
   FRONT...POTENTIAL WILL EXIST FOR EMBEDDED SUPERCELLS AND BOWS
   CAPABLE OF SIGNIFICANT SEVERE HAIL/WIND.

   ...SRN HIGH PLAINS...
   MOST OPERATIONAL GUIDANCE SUGGEST ISOLATED TO WIDELY SCATTERED
   HIGH-BASED TSTMS WILL FORM ALONG THE DRYLINE FRI AFTERNOON.
   HOWEVER...GUIDANCE DIFFERS WITH THE STRENGTH OF MID-LEVEL FLOW WHICH
   WILL MODULATE THE DEGREE OF ORGANIZATION. POTENTIAL DOES EXIST FOR
   MODEST MID-LEVEL SWLYS THAT WOULD BE SUFFICIENT FOR A COUPLE
   SUPERCELLS/MULTICELL CLUSTERS AS TROPOSPHERIC LAPSE RATES WILL BE
   STEEP. THIS MAY YIELD A FEW SEVERE HAIL/WIND EVENTS.

   ..GRAMS.. 06/20/2013

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z