Storm Prediction Center Mesoscale Discussion 781

   Mesoscale Discussion 0781
   NWS Storm Prediction Center Norman OK
   1010 PM CDT Mon May 18 2026

   Areas affected...portions of northern Oklahoma

   Concerning...Severe potential...Watch possible 

   Valid 190310Z - 190445Z

   Probability of Watch Issuance...60 percent

   SUMMARY...The severe threat may increase over northern OK over the
   next few hours as storms back-build southwestward along a southward
   drifting cold front. Severe gusts are the main threat, though an
   instance or two of hail or a tornado are possible. Convective trends
   are being monitored for the need of a WW issuance.

   DISCUSSION...Robust multicellular convection, with a history of
   measured severe gusts, has been steadily back-building
   west-southwestward along and immediately behind a southward sagging
   cold front. Despite weak upper support, strong low-level convergence
   has been supporting persistent convective development, especially
   given a 50 kt southerly low-level jet bisecting the cold front
   nearly perpendicularly. Ahead of the front, upper 60s F surface
   dewpoints beneath 8-9 C/km mid-level lapse rates are yielding 3000+
   J/kg MLCAPE per the 00Z OUN/LMN soundings and 02Z mesoanalysis.
   These same data sources also depict sizeable low-level hodographs
   with 300 m2/s2 effective SRH and 40+ kts of effective bulk shear. As
   such, the ambient environment clearly supports severe potential.

   The primary uncertainty is how far southwest convection will
   initiate along the southward-sagging front, and the timing for
   storms to propagate into OK. The current thinking is that storms
   capable of severe gusts will eventually propagate southward into
   north-central and northeast OK. An instance or two of severe hail
   could accompany the stronger storm cores, and a tornado cannot be
   ruled out if a robust updraft can outpace the cold front. Convective
   trends will continue to be monitored for convective propagation into
   OK.

   ..Squitieri/Mosier.. 05/19/2026

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

   ATTN...WFO...TSA...OUN...

   LAT...LON   36779919 36929821 36999709 36969623 36739582 36449572
               36099589 35879664 35809745 35909809 36089856 36429904
               36779919 

   MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
   MOST PROBABLE PEAK WIND GUST...65-80 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN