SPC AC 140606

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0106 AM CDT Fri Jun 14 2019

   Valid 141200Z - 151200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN CO
   INTO MUCH OF KS...TX PANHANDLE AND SOUTH PLAINS...WESTERN OK...

   ...SUMMARY...
   Strong to severe thunderstorms may develop across parts of the Great
   Plains and Upper Midwest this afternoon and evening.

   ...Central/Southern Great Plains...
   The large-scale pattern will be rather nebulous across the
   central/southern Great Plains today. In the mean, a broad weak
   trough will move slowly eastward, with several embedded vorticity
   maxima likely to move through the mean trough position through the
   period. The primary surface low will likely remain across the
   northern Plains, though weak cyclogenesis is possible along the lee
   trough in the vicinity of the OK/TX Panhandles. Low-level moisture
   will continue to improve, with dewpoints rising into the 60s F
   across a broad area east of the surface trough/dryline. The
   increasing moisture, combined with persistent steep midlevel lapse
   rates, will support moderate-to-strong destabilization, with MLCAPE
   forecast to be in the 1500-3000 J/kg range by late afternoon. While
   midlevel flow will be modest at best, sufficient veering in the wind
   profile will support effective shear of 30-40 kt, sufficient for
   organized structures. 

   Timing, location, and coverage of convective initiation later today
   remain uncertain, given the rather complex large-scale pattern.
   However, convergence along the dryline should support at least
   widely scattered thunderstorm development, including a few
   supercells. The primary initial threat should be large hail, with a
   conditional significant hail risk given favorable midlevel lapse
   rates and buoyancy. Generally weak low-level shear should limit the
   tornado threat, though a tornado or two will be possible with any
   sustained discrete supercells. Some upscale growth is possible into
   the evening, with potentially an increasing severe wind risk. At
   this time, the greatest model consensus for a wind threat this
   evening is over portions of KS, though the potential for an
   MCS-related wind event remains unclear, given that the low-level jet
   is expected to veer and become focused east of the primary
   instability axis. 

   ...Montana into the Northern Great Plains/Upper Midwest...
   General west-northwesterly midlevel flow will persist from MT into
   the northern Plains today, with a vorticity maximum forecast to move
   southeast into portions of eastern MT/western ND by this evening.
   Increasing low-level moisture and steep midlevel lapse rates will
   result in moderate destabilization, with MLCAPE of 1000-1500 J/kg
   forecast from much of MT into the Dakotas, MN, and perhaps northwest
   WI by afternoon. 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, where the boundary will likely
   be reinforced by early morning convection. 

   Midlevel 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. 

   Further east into portions of MN/WI, thunderstorm initiation will be
   possible this afternoon along the surface boundary/remnant outflow.
   While instability will be somewhat weaker compared to areas further
   west, stronger low-level flow/helicity will support the potential
   for a tornado or two with any sustained supercells, in addition to
   some hail/wind threat. If confidence increases in the potential for
   multiple rotating storms across this region, an upgrade may be
   needed in subsequent outlooks. 

   ...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. Sufficient elevated instability and
   effective shear will support some hail threat with the strongest
   storms. There would also be some potential for damaging wind if any
   upscale-growing system moves in from the west or develops from
   renewed elevated convection overnight. This wind scenario is too
   uncertain at this time for wind probabilities to be extended very
   far to the east, but future outlooks will revisit this potential.

   ..Dean/Elliott.. 06/14/2019

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