It is understandable to be skeptical after strong/violent tornadoes didn’t materialize over a wide area on May 6 this year, but that day did feature dozens of tornadoes across the Southern/Central Plains. This time around, I can’t stress this enough, I can’t find much wrong with tomorrow other than the fact storms may not be very widespread.

But I also think there is a good reason to expect a lot of storms tomorrow. In short: If isolated supercells are ongoing tomorrow from 5 p.m. onwards, big tornadoes will be occurring. If you get a handful of supercells, tomorrow may be downright historic. The environment is maxed out in every index.

Locations:

  • Primary Risk Area: Much of Kansas, Oklahoma, and far western Missouri.

Threats:

  • Strong to Violent Tornadoes: Particularly in the primary risk area.
  • Extreme Hail: Potentially exceeding 4 inches in diameter.
  • Widespread Wind Damage: Possible corridors of extreme wind damage, especially as storms evolve into a severe MCS (Mesoscale Convective System).

Timing:

  • Storm Initiation: Expected to begin late afternoon and early evening.
  • Main Severe Threat: Late afternoon into the night.

Meteorological Discussion:

  • Central and Southern Plains:
    • Setup: A fast-moving shortwave trough will move from the Four Corners states into the central Plains, with a deepening surface low over western Kansas by 00Z. A warm front will extend from northwest Texas into Arkansas in the morning, moving north across Oklahoma, southern Kansas, and southwest Missouri by evening.
    • Conditions: South of the warm front, a very moist and unstable air mass will develop, with dewpoints in the mid-70s F from Texas into Oklahoma. Strong southerly low-level flow will increase, enhancing moisture and instability.
    • Storm Development: Initially, storms will form near the developing cold front and surface low in western Nebraska and western Kansas by 21Z. These storms will likely be high-based supercells, capable of producing very large hail. As the evening progresses, the tornado threat will increase with long-lived supercells evolving eastward. Extreme hail over 4 inches is expected with the strong instability and upper-level wind speeds.
    • Storm Evolution: Storms are expected to merge into a severe MCS, with potential corridors of extreme wind damage as it moves into eastern Kansas and far western Missouri late in the evening.
    • Southern Sector: Along the dryline and within the open warm sector across Oklahoma and into Texas, isolated supercells capable of destructive tornadoes and extreme hail are possible late in the day and evening. Mesoscale conditions will need close monitoring for low-level confluence lines within the deepening moist sector east of the dryline.

Technical Discussion

There are two main areas to watch for storm formation. One is in Western Kansas into SW Nebraska and the other is down the dryline in Oklahoma. In the latter section, as has been the case many times this season already, I would expect storm coverage to exceed model expectations.
At 500mb, a powerful system is nosing out onto the Plains, with very strong flow for late May. This will create a dangerous environment tomorrow.
A broad and powerful low-level jet, with 850mb winds of 40kt+ already in the early evening, will be in place. Any robust supercells tomorrow will be producing tornadoes in the evening.
In terms of storm ingredients, I can’t think of a more favorable environment than what is depicted tomorrow, especially across Oklahoma where extreme instability and strong wind shear will combine with incredible (400+) effective SRH values. The only thing keeping tomorrow from being a high risk is storm coverage, and once a favored corridor becomes established, it would be entirely unsurprising to see a risk area outline for a high risk. The failure mode tomorrow would be capping preventing a ton of storms from forming — but I’m not seeing a strong cap on most models. With the strong lift, I’m just not sure even a moderate cap would prevent storms from forming. If you get more than a couple of supercells, tomorrow could border on historic.