Multiple rounds of severe thunderstorms are expected to tear across the Midwest on Monday. The storms, capable of producing damaging winds, large hail and intense tornadoes, are predicted to be most severe in the afternoon and evening.
There is potential for thunderstorms across a large area from West Texas to the Great Lakes, but northeast Iowa into southeast Minnesota and western Wisconsin is expected to be in the bull’s-eye of severe weather. This area, which includes Minneapolis and St. Paul, Minn., is under a relatively high risk (Level 4 out of 5) of severe weather, according to the National Weather Service’s Storm Prediction Center.
As for timings, Matt Mosier, lead forecaster at the Storm Prediction Center, said the most dangerous period would most likely be from late Monday afternoon into the evening. Storms are expected to develop in Minnesota and Iowa before moving eastward into Wisconsin, he said.
The most widespread threat will be large hail, with some areas seeing pieces as big as Ping-Pong balls. This hail threat will stretch from the upper Midwest down into parts of the southern Plains. Even larger hail, up to the size of tennis balls, is possible in some spots.
The risk of damaging winds, some over 60 miles per hour, and tornadoes will affect a narrower area.
“The wind potential is concentrated up in the upper Midwest, mainly in Minnesota and Wisconsin,” Mr. Mosier said, noting that there was “significant” tornado potential in the same areas.
An area spread between the northern Plains and the upper Midwest is at a marginal risk, (Level 1 out of 4) for heavy rains that could lead to flooding. The Quad Cities and the Twin Cities, along with Milwaukee and Madison, Wis., could see isolated flash flooding.
The central and southern Plains are also facing a marginal risk on Monday, particularly across north-central Oklahoma, the Concho Valley and the Western Rolling Plains of West Texas. In these areas, recent heavy rains have already soaked the ground, which increases the likelihood of flash flooding.
Strong storms are not unusual in the middle of the country in the spring; several thunderstorms unleashed strong winds, large hail and tornadoes in the Central United States last week. There were reports of hail as large as grapefruits in Texas and over a dozen tornadoes in the Great Plains on Friday, and thunderstorms brought flooding to New Orleans last week.
While last week’s thunderstorms were driven by numerous smaller storms, the weather on Monday will be associated with one stronger system.
“We will start off with a couple systems, but by the time we go through the day Monday, it’s evolving more into a larger single system,” said Rich Bann, a meteorologist with the Weather Service’s Weather Prediction Center. “The evolution of the upper winds will allow that one system to become better organized.”
On Tuesday, the severe weather is expected to shift from western Texas and Oklahoma to portions of the Ohio Valley and Northeast, with the greatest risk across eastern Ohio, northwest Pennsylvania and western New York. There will still be a risk of large hail and damaging winds. The tornado threat will ease, “but it certainly doesn’t go away in places like Oklahoma,” Mr. Bann said.
The southern Plains will be at risk of flash flooding on Tuesday. Storms are expected to move over the area repeatedly, dumping precipitation on the already saturated ground. As a result, a moderate risk (Level 3 out of 4) for excessive rainfall has been issued for parts of southwest Oklahoma and northwest Texas. A wider area is under a slight risk (Level 2 of 4) of extended rainfall, extending northeast toward the Mid-Mississippi Valley and southwest into the Texas Big Country, where scattered flash flooding could also occur.
The threat of severe weather is expected to continue through Thursday from the southern Plains to the Great Lakes, as the storm system slowly moves east.
“On Wednesday we’re still looking for heavy rainfall over the southern Plains, pushing into the mid-Mississippi Valley area later in the day,” said Brian Hurley, a meteorologist with the Weather Prediction Center. “By the time we get into Thursday we have more widespread rain across areas east of the Mississippi and Ohio Valley into the Appalachians, but it doesn’t look to be as heavy.”
By the weekend, conditions should calm as the storm moves off to the east. “Thankfully the weather starts to quieten down, especially as we get beyond Friday, when high pressure moves in for the weekend in the east,” Mr. Hurley said.
