Just like we mentioned yesterday, if we ever say the words in the headline above know we don’t do that often. I know some groups out there say these words a lot, but this is a case when it really is true. Today is going to be a long day.

An intense regional outbreak of severe weather is expected today, from this afternoon through evening, across parts of the south-central Plains. The most severe activity, characterized by multiple strong, long-tracked tornadoes, very large hail, and severe thunderstorm gusts, is anticipated over western, central, and northern Oklahoma to south-central Kansas.

Locations:

  • High Risk Area: Western, central, and northern Oklahoma to south-central Kansas.
  • Broader Risk Areas: Surrounding areas could also experience severe weather conditions but at a slightly lower intensity.

Threats:

  • Tornadoes: Multiple strong, long-tracked tornadoes are highly likely.
  • Hail: Very large to giant hail, potentially over 3 inches in diameter.
  • Wind: Severe thunderstorm gusts capable of significant damage.

Timing:

  • Initial Storm Development: Expected by mid to late afternoon along and ahead of the dryline, near the eastern Texas Panhandle/western Oklahoma line extending into southern Kansas. More storms could form over the open warm sector to the east, posing similar threats as those to the west.
  • Peak Activity: Late afternoon through late evening as conditions become increasingly favorable for severe weather.

Discussion

  • Weather Patterns: A strong synoptic-scale trough is moving from the northern Rockies through the central U.S., accompanied by a basal shortwave trough that will influence severe weather development as it swings northeastward. This system will become negatively tilted, enhancing its severe weather potential.
  • Atmospheric Dynamics:
    • Surface Features: A surface low analyzed over eastern Wyoming, with a cold front extending across eastern Colorado into north-central New Mexico, will progress eastward. This front will interact with a dryline that will advance to southwestern Kansas, eastern Oklahoma, and Texas Panhandles by late afternoon.
    • Severe Potential: The approach of the shortwave trough will enhance lifting mechanisms across the risk area. Combined with high instability and significant moisture (dewpoints in the upper 60s to low 70s Fahrenheit), the environment will be highly conducive to the development of supercells capable of producing all forms of severe weather.

Impact: Today’s severe weather setup indicates a critical risk level for parts of Oklahoma and south-central Kansas, where communities should prepare for potentially life-threatening conditions. The forecast suggests an unusually favorable environment for the development of strong, long-tracked tornadoes and resembles past major tornado outbreaks in the region. This is a day to cancel plans and prepare to take quick action.

Technical Discussion

Here is the graphic that I believe led to the High Risk. There is a continuous and strong signal across some of our weather models of not only dryline initiation (which you can see NW of Woodward) but open warm-sector storm initiation from Marlow to Alva. If this latter mode happens, that means a few areas will have a chance at seeing multiple rounds of supercells with strong to violent tornadoes possible.
As storms first go up, they may go up in a slightly less favorable environment initially. This environment does still support tornadoes, but it is on the more average end of what you’d expect for this time of year. But this will be short-lived.
The atmosphere rapidly improves into the early evening, with the environment becoming conducive for strong, long-tracked tornadoes prior to sunset. Effective SRH of over 250 along with 3CAPE of over 100 j/kg is an environment that is classically associated with strong, violent, long-track tornadoes.
Unfortunately, while the environment around 6 is bad, the environment at sunset is downright worrisome. Effective SRH values of over 400 mixed with continued strong 3CAPE (over 100 j/kg) is an environment reserved for the highest-end violent tornadoes. ANY supercell ongoing at sunset is likely going to be producing a major league tornado. And we don’t expect just one.
And I wish that were the end of it, but we expect supercells to continue into the night, at least to 10-11 p.m. And the environment only continues to get more ridiculously favorable for tornadoes, with effective SRH of over 600 and 3CAPE remaining above 100 j/kg. In short: Any supercell at this time may have a monster on the ground.
In short, I hope I look ridiculously alarmist at the end of the day — but we have a policy of NOT using this type of language unless it is warranted. This is because we want it to be the case that when we say “oh no” you know we mean it. There are too many weather accounts out there that call every setup major, historical, you name it — but we aren’t them. We are proud of that. So when we say these things, know the threat is both real and likely to happen. May 6, 2024 may be etched into history in the worst ways. Know your safety plan, don’t make plans for this evening. And for the love of God, stay weather aware today.