SPC AC 141250

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0750 AM CDT Fri Jun 14 2019

   Valid 141300Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE CENTRAL AND SOUTHERN PLAINS...

   ...SUMMARY...
   Strong to severe thunderstorms are expected over parts of the Great
   Plains and Upper Midwest this afternoon and evening. Isolated large
   hail and damaging wind gusts are the main threats.

   ...Central through southern Plains...

   Ongoing early morning showers and storms from KS into OK associated
   with a progressive shortwave trough and convectively induced MCVs
   continue east toward the MS Valley. In wake of this activity, low
   level dewpoints generally in the low-mid 60s F will advect through
   the warm sector beneath warm air (12-14C) at 700 mb associated with
   an eastward-expanding elevated mixed layer. These processes will
   result in moderate to strong instability (1500-3000 J/kg) MLCAPE) as
   the boundary layer warms during the afternoon, but the moist warm
   sector should remain capped much of the day. Initial storms will
   probably develop over the higher terrain of CO and NM and in the
   more deeply mixed regime west of the dryline. Isolated storms will
   also be possible along the dryline southward through west Texas.
   Storms will eventually intercept greater low-level moisture, but
   also more convective inhibition as they spread east through the
   Plains during the early evening. A corridor of modest 25-35 kt
   mid-level zonal winds will reside from northern portions of the
   southern Plains to the central Plains with 30-40 kt effective bulk
   shear supportive of both multicells and some supercell structures.
   Downburst winds and large to very large hail will be the main
   threats. Some potential may also exist for some of this activity to
   grow upscale during the evening, especially across KS on the nose of
   a strengthening low-level jet. However, given expected substantial
   increase in surface-based inhibition, it is possible surface based
   storms could begin to struggle, but additional elevated storms may
   develop. Will maintain slight risk category this update, but an
   upgrade to enhanced might be needed in later outlooks if greater
   confidence is attained that storms will evolve into a sustained,
   organized MCS.  

   ...Montana into the Northern Great Plains...

   Modest west-northwesterly mid-level winds will persist from MT into
   the northern Plains, with a vorticity maximum forecast to move
   southeast through MT before reaching western ND this evening.
   Increasing low-level moisture and steep midlevel lapse rates will
   result in MLCAPE of 1000-1500 J/kg. Thunderstorm initiation will be
   possible across the higher terrain of central/northwest MT, and also
   along a surface boundary that will likely extend from a surface low
   over the central Dakotas into central MN/western WI.

   Mid-level flow will be sufficient to support effective shear of
   generally 25-35 kt across the region, though the shear will be
   locally greater in the vicinity of any surface boundaries. Organized
   multicells/clusters and perhaps a couple of supercells will be
   possible within the broad northwesterly flow regime from MT into the
   Dakotas, with a corresponding risk of hail and locally severe wind
   gusts.

   ...Upper Mississippi Valley region... 

   Thunderstorm initiation will be possible this afternoon along the
   surface front/remnant outflow. While instability and lapse rates
   will be weaker compared to areas further west, stronger low-level
   flow/helicity will support the potential for organized storms
   including a couple of supercells with threat for hail, gusty winds
   and possibly a tornado. This region will continue to be monitored
   for a possible slight risk upgrade in the next day 1 update.

   ...Portions of MO Overnight...

   Elevated convection is possible overnight across much of MO as steep
   midlevel lapse rates move in from the west and the low-level jet
   becomes focused in this region. Moderate elevated instability will
   support some hail threat, but effective shear is expected to be
   modest (generally below 35 kt), suggesting overall threat should
   remain marginal unless greater confidence is obtained that upscale
   MCS growth will occur.

   ..Dial/Goss.. 06/14/2019

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