SPC AC 220519

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1219 AM CDT SAT JUN 22 2013

   VALID 221200Z - 231200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR THE N-CNTRL HIGH PLAINS
   INTO THE UPPER MS VALLEY AND UPPER MIDWEST...

   ...SYNOPSIS...
   AN UPPER TROUGH CENTERED OVER ORE/ID EARLY THIS MORNING WILL EJECT
   EWD INTO THE NRN HIGH PLAINS BY TONIGHT AS A SECOND WAVE DIGS SEWD
   TOWARD THE PAC COAST. AS THIS OCCURS...MIDLEVEL HEIGHT FALLS AND
   30-50 KT UPPER-LEVEL SWLYS WILL SPREAD DOWNSTREAM ACROSS THE
   CNTRL/NRN PLAINS. AT THE SURFACE...LOW PRESSURE WILL REMAIN ANCHORED
   OVER THE CNTRL HIGH PLAINS...WITH A STATIONARY FRONT EXTENDING NEWD
   INTO SERN SD...WHICH WILL TRANSITION INTO A WARM FRONT THAT MAY LIFT
   NWD INTO CNTRL MN/WI DURING THE DAY. IN ADDITION...A DRYLINE WILL
   EXTEND SSW FROM THE SURFACE LOW INTO ERN NM AND FAR W TX. SIMILAR TO
   THE PAST COUPLE OF DAYS...THE STATIONARY AND WARM FRONTAL BOUNDARIES
   WILL AID IN FOCUSING SCATTERED TO NUMEROUS THUNDERSTORMS DURING THE
   D1 PERIOD AS STRONG SLY FLOW TRANSPORTS A MOIST/UNSTABLE AIRMASS
   INTO THE FRONTAL ZONE.

   ...N-CNTRL HIGH PLAINS INTO THE UPPER MS VALLEY/UPPER MIDWEST...
   AN MCS WILL BE ONGOING AT THE BEGINNING OF THE FORECAST PERIOD FROM
   PORTIONS OF ERN NEB INTO MN AND WI...AND MAY POSE A MARGINAL SEVERE
   WEATHER THREAT DURING PART OF THE MORNING. FOCUS WILL THEN TURN TO
   AN UPSLOPE FLOW REGIME OVER THE N-CNTRL HIGH PLAINS. LOW-LEVEL
   CONVERGENCE IS FORECAST TO STRENGTHEN BY EARLY TO MID AFTERNOON FROM
   ERN WY INTO NERN CO AS A MIDLEVEL SHORTWAVE TROUGH EJECTS EWD TOWARD
   THE REGION. DEWPOINTS IN THE 50S APPEAR PROBABLE OVER ERN WY...WRN
   NEB...AND WRN SD...AND WILL AID IN MODERATE INSTABILITY AS THE
   BOUNDARY LAYER DESTABILIZES. INITIAL STORMS WILL LIKELY BE
   SUPERCELLS GIVEN THE PRESENCE OF LOW-LEVEL ELY WINDS SURMOUNTED BY
   40 KT MID/UPPER-LEVEL SWLYS. THESE STORMS WILL BE CAPABLE OF
   PRODUCING LARGE/VERY LARGE HAIL AND A COUPLE OF TORNADOES.

   STORMS OVER THE HIGH PLAINS WILL LIKELY DRIFT EWD INTO WRN/CNTRL NEB
   AND SWRN/S-CNTRL SD DURING THE EVENING...WITH UPSCALE GROWTH INTO AN
   MCS POSSIBLE. ADDITIONAL SCATTERED TO NUMEROUS THUNDERSTORMS ARE
   ALSO EXPECTED TO FORM NEWD ALONG THE STATIONARY FRONT FROM WRN NEB
   INTO SRN/CNTRL MN DURING THE LATE AFTERNOON AND EVENING. STRONG
   HEATING ALONG AND S OF THE BOUNDARY COMBINED WITH SURFACE DEWPOINTS
   IN THE MID 60S TO AROUND 70F AND STEEP MIDLEVEL LAPSE RATES WILL
   SUPPORT STRONG TO EXTREME INSTABILITY...WITH MLCAPE VALUES RANGING
   FROM 3000-5000 J/KG. WIND PROFILES WILL SUPPORT AN INITIAL MODE OF
   MULTICELL CLUSTERS AND SUPERCELLS POSING A THREAT OF VERY LARGE HAIL
   AND PERHAPS A TORNADO. INCREASING LARGE-SCALE ASCENT ASSOCIATED WITH
   THE TROUGH APPROACHING FROM THE W...COMBINED WITH STRONG MESOSCALE
   ASCENT AS THE EXIT REGION OF A 50+ KT LOW-LEVEL SLY JET IMPINGES ON
   THE FRONT...WILL PROMOTE UPSCALE GROWTH INTO A FORWARD PROPAGATING
   MCS DURING THE NIGHT...WITH A SWATH OF DAMAGING WIND GUSTS POSSIBLE
   FROM CNTRL NEB INTO NRN IA/SRN MN.

   ...SRN HIGH PLAINS...
   ISOLATED THUNDERSTORMS ARE FORECAST TO INITIATE ALONG A DRYLINE
   ORIENTED NE-SW FROM THE WRN TX PANHANDLE INTO FAR ERN NM AND FAR W
   TX. STRONG SURFACE HEATING COMBINED WITH DEWPOINTS IN THE 50S AND
   STEEP MIDLEVEL LAPSE RATES WILL AID IN AFTERNOON MLCAPE VALUES FROM
   1000-2500 J/KG. VEERING WIND PROFILES WILL SUPPORT MULTICELL
   CLUSTERS AND A FEW SUPERCELLS POSING A THREAT FOR ISOLATED LARGE
   HAIL AND DAMAGING WIND GUSTS.

   ..GARNER/MOSIER.. 06/22/2013

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