Level 4 of 5 Storm Threat in Place for Swath of the Midwest

Storms are erupting across the Midwest, impacting millions of Americans with a slew of severe impacts. Here is what you can expect as the day progresses, as well as where the storms are headed next.

Storms Igniting Across the Midwest, Threatening Severe Impacts

Forecasters have been warning for days about the likelihood of a major severe weather outbreak in the nation's heartland on Wednesday. The forecast is coming to fruition as several alerts have already been issued. The Storm Prediction Center (SPC) has issued a Level 4 out of 5 severe storm threat for north-central Illinois and the western edge of Indiana.

The midweek storm event is happening just days after a severe weather outbreak across the same general region. Likely impacts of Wednesday's storm event include damaging winds, large hail, flash flooding, and tornadoes.

The National Weather Service (NWS) issued a Severe Thunderstorm Watch for parts of Iowa and northwest Illinois on Wednesday morning. The greatest concentration of storms is expected in a zone just south of Chicago across northern Illinois and into northwestern Indiana. Violent tornadoes and flash flooding are the biggest concern for this area.

Some of the storm cells could also pack dangerous straight-line winds. This same situation unfolded last week across the Midwest when dozens of tornadoes with ratings up to EF-3 were reported across the central U.S. Several homes were destroyed during this outbreak while the high winds brought down trees and power lines, cutting power to over 500,000 customers.

Illinois leads the nation in tornado reports so far this year, an anomaly that has not gone unnoticed by climatologists. The storm track this year has taken the worst of the activity straight through the center of the nation, sparing the traditional Tornado Alley the worst impacts.

Wednesday's unsettled weather is being fueled by a strong area of low pressure that will push through the Midwest and into the Great Lakes. In addition to the Level 4 out of 5 threat for parts of Illinois and Indiana, the SPC has issued a Level 3 out of 5 risk for a swath of real estate from Kansas City to St. Louis and to the north into Chicago. Meanwhile, a broader Level 2 out of 5 risk is in effect for a more widespread area encompassing Kansas to the east into cities such as Louisville, Indianapolis, and Columbus.

Lastly, a Level 3 out of 4 flash flood risk has been predicted for northern Illinois into southern Michigan. The NWS has issued Flood Watches for this area as heavy rain is expected to train over the same general area for a longer period of time.

The likely flood impact zone is shifting to the south as the day progresses. The storm complex centered on northern Illinois is serving as an atmospheric roadblock, keeping the warm front from moving to the north. Rainfall rates of up to 2 inches per hour are possible. Widespread rainfall of 3 to 5 inches is in the forecast for much of the Midwest and beyond.

Two Rounds of Storms Likely

The updated forecast models suggest that the storms will ignite in two separate rounds. Some communities began experiencing the first round of stormy conditions by the late morning and early afternoon hours. Hail measuring up to 2.5 inches in diameter is possible at this time.

This initial wave of storms arrived in Chicago by the late morning hours. The severe impacts triggered loads of flight disruptions, including a temporary ground stop issued for Chicago O'Hare International Airport. Most inbound flights heading to this major hub have been affected. Average departure delays were sitting at 30 minutes and climbing. Passengers are being urged to monitor their flight status at O'Hare and across the region.

The second round of storms is forecast to fire up later in the day as the atmosphere continues to destabilize along with the natural heating of the day. The strong wind shear already in place will support the development of supercells capable of unleashing long-track tornadoes rated EF-3 or stronger. These storms will continue to rage into the evening and overnight hours, carrying the risk of winds up to 75 mph.

There is also the chance that this storm complex could evolve into a derecho. This threat is most likely for the Ohio Valley. A derecho is defined as a long-lived straight-line wind gust that can travel on the ground for hundreds of miles.

A potent low-level jet stream will send the storms along at a fast clip. This means that the potentially dangerous conditions could seemingly come out of nowhere.

Looking ahead, the stormy weather is forecast to target the Northeast beginning on Thursday. The threat of storms will encompass the major cities along the Interstate 95 corridor, including Washington, D.C., Philadelphia, New York City, and Boston. The atmosphere will then reload again by the weekend across the central portions of the country, putting severe storms back on the table.

Stay tuned as we provide more updates about the storms setting up across the central and northeastern U.S.

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