60 million at risk for severe weather in the Midwest

A dangerous severe weather outbreak is looming for the central Plains, Great Lakes and Ohio Valley, with more than 60 million people at risk through the weekend, AccuWeather meteorologists warn.

"An unusually vigorous storm system for August will push out of the northern Rockies and across the north-central United States this weekend," AccuWeather senior meteorologist Brett Anderson said. "The storm will tap into Gulf of Mexico moisture and will have extra energy from a strong jet stream overhead."

Following severe thunderstorms in portions of the High Plains from South Dakota to Nebraska, Kansas, Wyoming and Colorado into Friday night, the area at risk for dangerous thunderstorms will focus farther to the east over the Plains on Saturday.

AccuWeather meteorologists say a moderate risk of severe thunderstorms will extend from southeastern South Dakota, southwestern Minnesota and western Iowa to southeastern Nebraska and north-central Kansas from Saturday to Saturday night. Kansas City, Mo., Omaha, Neb., and Des Moines, Iowa are among the major cities at risk for severe weather.

"Thunderstorms are expected to form a squall line -- a solid line of severe weather -- that races to the east and southeast into Iowa, Kansas and Missouri late in the day and through the night with the primary threat being damaging wind gusts, in addition to large hail," Anderson said.

However, any individual, discrete severe thunderstorm may produce tornadoes, especially from southeastern South Dakota through eastern Nebraska and into Kansas and northwestern Missouri, Anderson stated.

Outside of any tornado, wind gusts ranging from 60-70 mph are likely in the stronger storms.

Sunday may bring a much higher tornado risk compared to Saturday as the storm system shifts farther to the east.

"On Sunday, a combination of discrete cells as well as a squall line of severe thunderstorms is foreseen," Anderson said.

AccuWeather meteorologists have outlined a large moderate risk of severe weather for Sunday that stretches from southeastern Wisconsin and southwestern Michigan to western Kentucky and includes a large part of Illinois and Indiana. This area is expected to be at the greatest risk for tornadoes.

The AccuWeather forecasting team will be monitoring this area closely as there is the potential for part of this zone to be upgraded to high risk.

Major Midwest cities that could be blasted by severe thunderstorms on Sunday include Chicago, Detroit, St. Louis, Indianapolis, Cincinnati and Nashville.

At 125 tornado reports and counting so far this year, Illinois leads the nation in the twister count as of early August. The state has reported the most tornadoes since 2006 when 144 twisters were confirmed, according to the National Oceanic and Atmospheric Administration.

Wind gusts in many of the storms will range from 60-70 mph.

Motorists should expect delays and dangerous conditions on the roads and highways over the North Central states this weekend. Torrential downpours can lead to a sudden drop in visibility, flash flooding and the risk of hydroplaning.

Where severe thunderstorms repeat or overlap areas that were drenched with heavy rain much of this week from Nebraska to Missouri, Illinois, Tennessee and Kentucky, more flash flooding can occur.

The scope and magnitude of severe weather in the Midwest on Sunday could lead to major airline delays and ground stops as storms approach the major airport hubs. The number of flight cancellations is likely to increase through Monday.

Airline passengers elsewhere in the United States with connecting flights to the Midwest or as their final destination could be adversely affected.

The same storm system will push slowly into the Northeast on Monday, where flight delays may mount later in the day in some of the major hubs from Pittsburgh to New York City, Philadelphia, Boston and Washington.

North of the storm track, there will be significant rainfall from northern South Dakota through a large portion of Minnesota.

"Widespread rainfall amounts in the 1- to 2-inch range with localized amounts in excess of 3 inches," Anderson said.

While there can be localized pockets of flash flooding through this region, the bulk of the rainfall will be beneficial as many areas remain in a drought, Anderson added.

A period of drenching rain may pivot southeastward across a portion of the Great Lakes region from Sunday night to Monday in the wake of the severe weather threat.

Tornadoes can occur year-round, but outbreaks of tornadoes are much more common during the spring to early summer season rather than midsummer from the central Plains to the Ohio Valley states. This is due to the northward retreat of the jet stream.

A tornado scoured the ground and caused damage near Woodburn, Ind., on Aug. 24, 2016. Photo by Scott Jordan Drone Footage/NWS Storm Survey

However, in a setup not much different from this weekend, nearly two dozen tornadoes touched down in the Midwest on Aug. 24, 2016, according to NOAA.

Indiana and Ohio each had 11 confirmed tornadoes on this day with the strongest being an EF3 tornado with winds of 160 mph in Woodburn, Ind. Fortunately, there were no fatalities reported during the outbreak.