Forecast Courtesy of: KRZY
Click here to be directed to the Global Weather & EAS Society Discord, and join in on the conversation!
A severe weather and tornado outbreak of a caliber possibly not seen in 12 years is highly likely throughout the entire Great Plains. Several violent tornadoes appear possible. The main risk area should be from central and eastern Oklahoma, through central and eastern Kansas, western Missouri, and parts of northwestern Arkansas and south/southeastern Nebraska. Those in the affected areas need to secure their tornado plans NOW.
Setup
A two step ejection should occur within the larger wave axis, starting with the lead wave which should eject into the northern plains by early to mid afternoon, bringing with it the primary surface low, which should deepen into the mid 980s. However. It appears that generally broad surface cyclogenesis will still be present across the entire central plains as well, which will allow the mass response with this system to be anomalously broad.
The southern parts of the mass response should be aided by another jet streak arriving from the west. This system has trended significantly stronger throughout the day today, with now around 110kts of flow within the core of the jet streak appearing likely. At least currently, it appears that increased synoptic lift from this will be present across the entire central plains, however, the core of the strongest forcing won’t arrive into Oklahoma and southern Kansas until closer to sundown.
Thermodynamics
Thermodynamically, it’s clear that this system is nearly unlimited, with 60s dewpoints likely making it to southern Nebraska, and deeper mid 60s dewpoints making it into at least south central Kansas by the time storms should fire. Into Oklahoma, it appears that there even may be a robust corridor of 70s dewpoints that develops, pending the exact potency of the mass response. Most model soundings indicate a thermodynamic environment characterized by 2-3000CAPE in Kansas, with 3000-4500CAPE in Oklahoma.
CAPE may generally be just a hair less potent than this given there has been a conflict between models and reality. However, that will be practically meaningless and will not serve to lessen the extent of this outbreak.
Timing and Impacts – Afternoon, Early Evening
Storms should fire off of the dryline early (17-19z) in southern Nebraska and northern Kansas, boasting an initial large hail risk, before transitioning into likely the first significant tornado producers of the day while the atmosphere continues to destabilize further south.
As the northern storms likely grow upscale around 20-21z, it appears likely that we will see the second leg of the event begin, which should feature several significantly tornadic supercells in central and southern Kansas between 20 and 23z. Forcing will likely be quite powerful in this region, however, the shear vector orientation aloft at 45-60 degrees off of the initiating boundary should favor long lived, discrete tornadic supercells in this region, which will easily be capable of all hazards, including strong to violent tornadoes.
Timing and Impacts – Evening
As storms grow upscale further north, a new batch of supercells should fire even further south into the Kansas/Oklahoma border, northern Oklahoma, and potentially even central Oklahoma. Environmental profiles here appear analogous to many higher end events in this region, and appear likely to foster potentially higher end, violent tornadoes with any robust supercells that do form.
In the southern mode, supercells may last particularly long (4+ hours) given the extremely favorable shear vector orientation, very wide warm sector, veer back veer in the midlevels, and lack of convective inhibition after 00z.
Renewed supercell development may even occur in an environment equally as favorable for intense to violent tornadoes after 00z in central Oklahoma as the strongest forcing from the jet streak arrives into the region. Eventually after 06z, the setup should begin to grow completely upscale into an MCS into Missouri and Arkansas, therefore lowering the tornado risk.