Looks like AR and MO are under the gun today. I wouldn't sleep on this.
Mesoscale Discussion 0722
NWS Storm Prediction Center Norman OK
0957 AM CDT Tue May 21 2019
Areas affected...Western AR and southern MO
Concerning...Severe potential...Watch likely
Valid 211457Z - 211630Z
Probability of Watch Issuance...80 percent
SUMMARY...A pre-frontal squall line will spread eastward and
northeastward into western Arkansas and southern Missouri through
late morning and early afternoon. Destabilization northward in
advance of the line will support a continued threat for a few
tornadoes with embedded circulations.
DISCUSSION...A pre-frontal squall line is moving eastward from
eastern OK toward western AR. As a pronounced upstream shortwave
trough begins to eject northeastward from northwest TX and western
OK, an associated surface cyclone will develop northeastward into
KS. The near-surface layer is still stable into southern MO per
surface observations and a 14z SGF sounding. However, the surface
warm sector will spread northward from AR into MO through the
afternoon, as the environment becomes more supportive of
surface-based convection into MO through the afternoon. Strong
deep-layer south-southwesterly vertical shear will support embedded
bowing segments and/or rotating storms within the convective line
into the afternoon. Given strong low-level shear and a moist
environment, there will continue to be a threat for occasional
tornadoes with embedded circulations in the line, as well as
damaging gusts and isolated large hail. The storms will progress
east of tornado watch 205 in the next 1-2 hours, necessitating a new
tornado watch into AR and MO after 16z.
..Thompson/Hart.. 05/21/2019