Synopsis
The synopsis for the setup remains similar, a powerful (albeit not very divergent) jet streak extending into central and southern Kansas in the mid and upper levels is expected to provide the forcing necessary for scattered supercell development along a secondary dryline in the central and southern Plains.
The surface low still appears the same as prior outlooks, and generally the pattern’s kinematics appear constant, with midlevel flow increasing throughout the afternoon and evening, and a rapid strengthening of the low level jet nocturnally, helping to rapidly advect deeper moisture in and provide storms with enough low level shear to transition into a strongly tornadic mode.
Fail modes? Even with that 00z HRRR run?
Even so, it appears that thermodynamically the 00z set of guidance has presented a few thermodynamic problems that could help to prevent this from being a truly high end tornado outbreak. These will be described below.
Note that this in no way devalues the very real threat for significant tornadoes — just don’t be surprised if the result is more conservative than model output.
1) A much larger batch of convection currently located over eastern Texas could partially ruin the thermodynamic environment advecting into Oklahoma, especially central and northern Oklahoma by lowering the dews (likely to the upper 60s to ~70).
More importantly it’ll make the moist layer shallower, which makes this airmass far more likely to mix out as it makes its way into Oklahoma during the afternoon of the event.
2) A thick cirrus plume expanding over the warm sector after 18z may prevent daytime heating and adequate destabilization for widespread coverage of powerful supercells.
In fact, should this be thick enough, it could stop powerful supercell production altogether. However, according to model output, this currently looks concentrated over northern areas of the risk.
So, even if this were to verify, it appears that a general area from Oklahoma City and southward should boast the highest chance of a couple intense to violent tornadoes even when taking into consideration these fail modes.
Northern Oklahoma, southern Kansas
Into northern Oklahoma and southern Kansas, it appears a few tornadoes are still possible, though there is more of a risk for large hail (early in the convective lifecycle) and damaging winds (potentially destructive towards the evening) given the much drier environment and the stronger forcing for ascent.
