There’s a significant risk of tornadoes today across a large portion of the Mississippi River Valley from Iowa down to Arkansas. Additionally, a significant risk of damaging winds also exists across portions of the Midwest.

This is a dynamic storm system that is going to have impact across multiple states with the severe weather threat stretching from Cleveland, OH to Austin, TX. Let’s dive in.

A compact trough with powerful mid-level jet stream winds will be nosing in across portions of the Midwest.
Further down in the atmosphere, the low-level jet stream winds will be cranking at 55-60 knots. This is a LLJ that you look for on big tornado days.
These strong atmospheric winds will combine with rich moisture from the Gulf of Mexico to create a very violative environment for a large swath of the country.

Broad Overview

Needless to say, the ingredients from a technical sense are all there for a significant day of severe weather. Strong wind shear and weak to moderate instability will be in place across a large swath of the country.

  • Surface dewpoints of 60+ will reach as far north as Northern Illinois today.
  • The 850mb winds will be 55kts or greater across a huge portion of the Mississippi Valley.
  • Winds at 500mb are approaching 100kts in the jet streak core.. This is a powerful early Spring storm system.
  • Severe weather is a certainty today.
Today’s SPC risk map.

How High is the Tornado Threat?

The Storm Prediction Centered has outlined a significant risk of tornadoes from Iowa/Illinois down to Arkansas/Mississippi. This is a huge swath of land that technically covers a few different types of environments. I’m going to do my best to summarize these but…this is a lot.

  • On the northern end, storms should fire ahead of the somewhat stacked low in Iowa early this afternoon. This is a setup where I think the highest tornado potential is very early in the event — storms should line out quickly so the initial supercells are the ones to watch. They could tornado very fast.
  • In the middle, including Missouri and portions of Southern Illinois — storm development should be more isolated. The core of the mid-level jet and strong low-level winds will combine here to create an environment favorable for a storm or two to produce big tornadoes. However, storm development here will be more sparse.
  • To the south, a volatile setup is once again present in the Southern US. Moisture will be abundant and wind shear strong — leading to a risk of tornadoes with any sustained, dominant supercell with clean inflow.

This is a true significant risk of tornadoes across a wide swath of land.

But…Storm Mode

I already talked about this in the previous paragraphs some, but I think storm mode is a possible obvious limiter of a much bigger tornado threat. I want to be clear, there will be tornadoes today — some strong. But what might be a blessed development today for many might be very crowded storm modes.

On the northern end of the risk ahead of the low, these storms that form early/mid afternoon in Iowa will be capable of producing tornadoes very quickly. This is because of the vorticity (spin) in the atmosphere from top to bottom so near the low pressure center. This is a target that storms could form quickly, produce a few tornadoes, and then line out all within 2-3 hours. Something to watch are the fairly unidirectional winds at the start which do limit shear some, which may mitigate the overall risk initially. Tornadoes will still be possible within the line, but the most significant risk will be with the initial supercells that form here.
South of the low across Missouri and Western Illinois, storms will be far more isolated and will also form later. I find it interesting that models do not produce much updraft helicity (UH) in this region despite an otherwise very favorable environment. It could be nothing, but could be something to watch.
Further to the south, the wind shear actually looks somewhat stronger due to stronger turning of winds with height in the atmosphere. However, storm mode also looks far more complicated. I think the story here is the same as most other events in this region — get a dominant supercell with clean inflow and you probably get tornadoes out of that supercell. But if storms line out and create a strong push of outflow ahead of them, the tornado threat will be lower, but not zero.
Overall the HREF points to the highest risk for rotating storms today across Iowa/Missouri/Illinois. With a secondary risk farther south in Arkansas/Mississippi/Tennessee.

The Bottom Line

Today certainly has the potential to be a high impact tornado event across a large swath of land. However, it is admittedly a more rare event for those types of days to take shape. I would bet on a pocket of tornadoes to the north near the low, and probably some more sporadic reports further south.

Crowded/messy storm modes may be the ultimate limiter of today, which will be welcome news to local residents if that does occur. But those were also limiters on March 24 for most storms except for one — underscoring that, when the ingredients are high end, a day only needs one storm to take advantage of those to generate devastating human impacts.

Stay weather aware today, make sure you can get warning alerts, and be sure to tune in to our live forecast briefing later this morning on our YouTube channel (will be embedded above after it is finished).