Mesoscale Discussion 0838
   NWS Storm Prediction Center Norman OK
   0217 PM CDT Sat Jun 23 2018

   Areas affected...Portions of Oklahoma and north Texas

   Concerning...Severe potential...Watch likely 

   Valid 231917Z - 232115Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms are expected to develop over western/central
   Oklahoma by late afternoon. Several will likely become severe,
   accompanied by a threat of large hail (some potentially 2+" in
   diameter), damaging winds, and perhaps a tornado. Watch issuance is
   likely.

   DISCUSSION...Visible satellite imagery shows developing cumulus
   along a boundary extending from western Oklahoma east/southeastward
   to near Norman. A 19Z OUN sounding sampled a subsidence inversion
   near 850-800 mb, although it has lifted considerably since 12Z.
   Subtle mid-level ascent is currently overspreading the region, and
   modest cooling aloft should combine with further surface heating to
   remove remaining inhibition over the next couple of hours. Steep
   mid-level lapse rates and a warm/moist boundary layer should
   contribute to around 2500-3500 J/kg of MLCAPE as well. In turn, once
   profiles near 850-700mb moisten sufficiently, rather robust
   convection is forecast to develop near the boundary.

   Ample veering of winds with height will likely support one or more
   high-precipitation supercells, capable of very large hail (2+" in
   diameter possible) and damaging winds. Although storm-relative
   helicity is not particularly strong, backed near-surface flow and
   any southeasterly propagation component may locally enhance the
   potential for a tornado. Over time, intense precipitation
   cores/outflow will likely force upscale growth into a complex that 
   accelerates south/southeast towards the Red River. Considering the
   threat, watch issuance will likely be needed within the next few
   hours.

   ..Picca/Thompson.. 06/23/2018

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...FWD...OUN...

   LAT...LON   33339846 33409869 33859926 34769975 35249980 35689982
               35789966 35729861 35649794 35589733 35009673 34069635
               33479628 33329697 33329770 33339846