SPC AC 181719

   DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1219 PM CDT TUE JUN 18 2013

   VALID 191200Z - 201200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS CNTRL AND ERN MT INTO NWRN
   ND...

   ...SYNOPSIS...
   A POTENT SHORTWAVE TROUGH IS FORECAST TO MOVE THROUGH THE BASE OF A
   LARGER SCALE TROUGH/ASSOCIATED UPPER LOW OVER THE PACIFIC NW AND
   THIS FEATURE IS FORECAST TO ACQUIRE A NEGATIVE-TILT AS IT MOVES INTO
   THE NRN ROCKIES/NRN HIGH PLAINS BY WEDNESDAY EVENING.  THE MID-LEVEL
   AMPLIFICATION OF A RIDGE WILL OCCUR DOWNSTREAM OVER THE CNTRL CONUS
   AS A TROUGH EXITS THE ERN SEABOARD INTO THE WRN ATLANTIC.  A SURFACE
   LOW IS FORECAST TO DEEPEN OVER MT THROUGH THE EARLY HALF OF THE
   PERIOD WITH A LEE TROUGH/DRYLINE EXTENDING SWD THROUGH THE CNTRL-SRN
   HIGH PLAINS.  A COLD FRONT WILL ACCELERATE EWD ACROSS THE NRN HIGH
   PLAINS WEDNESDAY NIGHT REACHING THE WRN DAKOTAS BY THURSDAY MORNING.
    
   ...NRN ROCKIES/NRN HIGH PLAINS...
   LEE CYCLOGENESIS WILL INDUCE THE CONTINUED NWWD TRANSPORT OF
   MOISTURE INTO THE NRN HIGH PLAINS AND FEATURE 50S BOUNDARY LAYER
   DEWPOINTS.  STRONG SURFACE HEATING AHEAD OF THE APPROACHING
   MID-LEVEL DISTURBANCE AND VERY STEEP MID-LEVEL LAPSE RATES /8-9 DEG
   C PER KM/ WILL RESULT IN 1000-2500 J/KG MLCAPE BY PEAK HEATING
   ACCORDING TO THE LATEST MODEL DATA.  EXPECTING ISOLD-SCTD STORMS TO
   DEVELOP BY THE MID AFTERNOON AND MOVE IN A GENERAL NWD DIRECTION
   OWING TO THE MERIDIONAL CHARACTER TO THE MID-UPPER FLOW.  THE
   PRESENCE OF STEEP LAPSE RATES AND SIZABLE CAPE IN THE -10 TO -30 DEG
   C LAYER SHOWN IN FORECAST SOUNDINGS WOULD SUPPORT A LARGE TO VERY
   LARGE HAIL THREAT EVOLVING WITH THE MORE INTENSE UPDRAFTS
   /SUPERCELLS/.  THE PROPENSITY FOR COLD POOLS TO COALESCE TOWARDS
   EVENING MAY INCREASE THE SEVERE WIND GUST THREAT AS CLUSTERS OF
   STORMS MOVE FROM CNTRL MT TOWARDS THE CANADIAN BORDER AND NERN MT
   DURING THE EVENING HOURS.  

   ...GREAT PLAINS...
   THE STRENGTHENING OF THE UPPER RIDGE /MID-LEVEL HEIGHT RISES/ OVER
   THE CNTRL CONUS CASTS CONSIDERABLE DOUBT IN ACCURATELY PORTRAYING
   THE TIMING/LOCATION OF A FEW AREAS OF ISOLD STORMS...AND LITTLE
   EVIDENCE SUPPORTS A CHANGE FROM THE PRIOR OUTLOOK TO A CATEGORICAL
   SLIGHT RISK OVER A PREFERRED AREA OF THE GREAT PLAINS. 
   NONETHELESS...A RESERVOIR OF MODERATE TO STRONG INSTABILITY WOULD AT
   LEAST SUPPORT A CONDITIONAL POSSIBILITY FOR VIGOROUS STORMS
   /SUPERCELLS/ CAPABLE OF A LARGE HAIL/SEVERE WIND GUST THREAT.  A
   PORTION OF THIS REGION MAY REQUIRE AN INCREASE IN SEVERE
   PROBABILITIES IN LATER OUTLOOK UPDATES IF HIGHER CONFIDENCE IN STORM
   LOCATION/COVERAGE IS MET.  A LINGERING CHANCE FOR ISOLD SEVERE
   STORMS MAY OCCUR DURING THE OVERNIGHT ON THE NOSE OF A CNTRL PLAINS
   50 KT LLJ.  

   ...NRN GULF COAST...
   DUAL FOCUSING MECHANISMS WHICH INCLUDE THE INLAND PENETRATION OF A
   SEA BREEZE FRONT AND THE TRAILING PORTION OF THE WRN ATLANTIC FRONT
   INTO THE NRN GULF COAST STATES...WILL PROBABLY LEAD TO ISOLD TO
   WIDELY SCTD STORMS DURING THE DAY.  POOR LAPSE RATES RESULTING IN
   WEAK BUOYANCY WILL ACT TO LIMIT UPDRAFT STRENGTH...PRECLUDING LOW
   SEVERE PROBABILITIES ATTM.

   ..SMITH/KERR.. 06/18/2013

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z