SPC AC 231744

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1244 PM CDT Sat Jun 23 2018

   Valid 241200Z - 251200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF SOUTHERN KANSAS INTO NORTHWEST OKLAHOMA...

   ...SUMMARY...
   Significant severe storms capable of destructive winds, very large
   hail and a few tornadoes are possible on Sunday across much of
   Kansas, northern Oklahoma and into the eastern Texas Panhandle. A
   few severe storms are also possible from Missouri toward Tennessee
   and Kentucky.

   ...Central/Southern Plains to Mid-Missouri Valley...

   A shortwave trough will migrate across the Plains, bringing a band
   of 40-50 kt southwesterly midlevel flow across the region. At the
   surface, rich low level moisture (dewpoints upper 60s to low 70s)
   will be in place ahead of a southeastward advancing cold front.
   Additionally, a dryline will extend southward from a surface low
   over the TX Panhandle. Convection will likely be ongoing across
   parts of NE at the beginning of the period. Further south, some
   cloud debris is possible from overnight convection in the Day 1
   period, but the airmass across KS into OK should experience strong
   heating. As such, an extremely unstable airmass will evolve by
   afternoon. 

   There is some uncertainty regarding convective evolution, with the
   NAM forecast continuing to be an outlier compared to other
   deterministic and hi-res guidance. Expect that one or more clusters
   will develop across NE along the front and track east/southeast
   through the morning. Additional storms will then develop southward
   along the front across western KS, as well as across the OK/TX
   Panhandles in the vicinity of the surface low/triple point. 40+ kt
   deep layer shear coupled with very steep lapse rates will favor
   initial supercells capable of very large hail and damaging winds.
   Cells likely will not stay discrete long and quick upscale growth is
   expected. The strength of deep layer shear and degree of instability
   will support widespread damaging winds, with many significant wind
   gusts possible. Any cell that can remain discrete will pose a
   tornado threat initially given high-quality low level moisture (mean
   mixing rations around 17 g/kg) and favorable low level shear.
   Additionally, embedded mesovortex circulations are possible once
   upscale growth occurs. One or more bowing segments are expected to
   track east/southeast across KS and northern OK overnight, with
   strong wind potential being maintained due to increasing 40-50 kt
   southwesterly low level jet. 

   Additional strong to severe storm are possible in warm advection
   across MO into IA. A very unstable and moist airmass will be in
   place, though deep layer shear will remain more modest. Still, steep
   low level lapse rates and high PW values could result in scattered
   strong wind gusts.

   ...Portions of the mid-Mo Valley into KY/TX Vicinity...

   A weak lead shortwave impulse will track eastward across the region
   during the afternoon. This will provide enough deep layer shear and
   forcing some organized cells capable of strong wind gusts. Lapse
   rates will remain poor in spite of moderate instability, limiting
   large hail potential.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   5%     - Slight
   Wind:     45% SIG - Moderate
   Hail:     30% SIG - Enhanced

   ..Leitman/Smith.. 06/23/2018

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