From the new MD
In addition, VWP data from KOUN and KVNX depict a notable increase
in low-level flow over the last hour, with some modest backing of
surface winds noted in recent Oklahoma Mesonet data. 0-1 km SRH of
around 200 m2/s2 was noted in the 21Z OUN sounding, with values
expected to increase above 300 m2/s2 into this evening. The
combination of strengthening low-level shear and strong to extreme
instability will support a rapid increase in potential for strong
and possibly long-tracked tornadoes as storms spread
east-northeastward this evening.