An upper low will approach the Southern Plains from the west, increasing lift along a front enough to touch off storms late this afternoon into tonight. Large hail will be the main threat, but damaging winds may also occur early on.

Most high-res models break out storms across OK, AR, and TX in the evening hours on Saturday.

Almost entirely nocturnal threat: Most high-res models show very little confidence in storm initiation before dark across much of the area. The best chance for storms in the daytime will be east-central Oklahoma into Arkansas.

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Big Hailers: The environment on Saturday suggests the potential for some big hail with the initial cellular activity. With time, storms will form into a line and the overall severe threat should diminish.

A forecast sounding from the HRRR near storm formation sones tomorrow evening.

Forecast Discussion: There is some uncertainty as to where the initial development will occur tomorrow.

  • Most models have initial storms developing along and north of I-40 around 7-8 p.m. This would put places like Oklahoma City in the biggest hail risk zone.
  • However, there are a lot more model differences than what is typical at this range. This will make figuring out the zone of initial development somewhat tricky.
  • The near-surface boundary should be pretty stable due to boundary layer cooling into the night, but ample 0-6km shear and cloud-layer shear should promote hail growth in the strongest updrafts.
  • The hail risk will likely peak from 8 p.m. to midnight or so.
  • Expect storms to gradually form into a line which will bring hail sizes down and wind speeds probably won’t push too far into severe limits if at all.

What’s Next: The overall blocking pattern should continue beyond this low’s passage underneath the block, if there are any additional severe weather chances they are certainly more than seven days out.