Strong Storm Threatens Midwest Tornadoes, Other Troubles

Areas shaded in orange and red have the greatest risk of
tornadoes Saturday. A couple tornadoes could be long-lasting
and strong.  Areas in yellow have a somewhat lesser but
still real chance of severe storms Saturday. 

As if people don't already have enough to worry about, a strong storm could unleash some tornadoes, possibly strong ones, and other dangerous hazards in the middle of the nation this weekend.

It's a classic spring storm setup. The disturbance is now getting going in Colorado and will move across Nebraska, Iowa, Wisconsin and into the Great Lakes by Sunday.

This storm will affect us here in Vermont, but it won't be nearly as dangerous as in parts of the Midwest.

Forecasters are especially worried about an area centered on northern Illinois on Saturday.  That area will be just to the southeast of the storm center.

This position will guarantee winds changing direction with height, one ingredient you need for rotating supercell thunderstorms, which can produce tornadoes.

Add to that very humid air streaming into that area, a  batch of drier air coming in from the west, and instability caused by the sun's heating during the day and you definitely increase the risk.

NOAA's Storm Prediction Center has a moderate risk for severe storms in northern Illinois Saturday, which is their second highest alert level.  It looks like supercell thunderstorms that are not connected to one another (they call them discrete supercells) will get going in that region Saturday afternoon.

When supercells are "discrete," they have a better chance of lasting a long time as they travel toward the east or northeast, and have a better chance of producing tornadoes. The Storm Prediction Center says a couple tornadoes could be very strong and long-lasting.

This setup in Illinois reminds me a lot of a similar situation in April, 2015 that produced 11 northern Illinois tornadoes, including an EF-4 that killed two people and injured a couple dozen others in Rochelle and Fairdale, Illinois 

A lesser, but real chance of severe storms and tornadoes will exist as far east as Ohio and as far south as Mississippi on Saturday.

Predicting tornado outbreaks is a very tricky business.  If just one subtle ingredient is missing, then nothing super bad will happen. If one little meteorological ingredient is a bit more robust than expected, watch out.  The bottom line is nobody is very sure what will happen in northern Illinois Saturday, but it definitely bears watching.

Elsewhere, the storm could produce enough heavy rain in central Nebraska and southeastern South Dakota. The storm looks like it will produce several inches of wet, heavy snow in northeastern Minnesota, near Lake Superior.

By the way, ahead of the main show on Saturday, a few severe thunderstorms are possible in eastern Kansas and Missouri later today. The main threat is really big hail, but a tornado or two can't be ruled out.

VERMONT IMPACTS

Nothing super dangerous will come out of this storm for us in the Green Mountain State, but Sunday looks like it will be a raw, ugly day.

Saturday looks gorgeous out ahead of the storm with relatively warm temperatures near 50. Sunshine will start to fade behind thickening clouds in the afternoon - a harbinger of the storm.

Sunday will feature rain, gusty winds, and freezing rain in spots. Most if not all of the freezing rain will be along and east of the Green Mountains during the first half of Sunday.  Any  ice accumulation will be pretty light, and the roads generally won't be too bad, as road surface temperatures are likely to be a bit above freezing.

Besides, hardly anyone is driving around these days, right?

There might even be a rumble of thunder thrown in here and there Sunday afternoon, we'll see.

In the spring, storms tend to slow down their forward speed, especially when they reach our neck of the woods and that will be the case this time.  So showers will keep going through Monday night, though the precipitation will be mostly lighter by Sunday night and Monday.

They're predicting about an inch of rain with this system in Vermont, give or take.  Rivers will rise, but this doesn't look quite big enough at this point to have us worry about any real flooding.

Here's a famous video taken by a person watching the 2015 Fairdale, Illinois tornado from his house. He thought it would miss, but it veered toward him, destroying his house, injuring him and killing his wife. It's a lesson: Tornadoes can change directions.  Even if you think you're safe, take cover just in case. Here's the video It's scary!