Millions at risk for severe weather in the Midwest

Rounds of severe thunderstorms swept across the central Plains and Ohio Valley, putting tens of millions of people at risk during end of the weekend according to AccuWeather meteorologists.

"An unusually vigorous storm system for August pushed out of the northern Rockies and crossed the north-central United States," AccuWeather Senior Meteorologist Brett Anderson said. "The storm tapped into Gulf of Mexico moisture and got an extra boost of energy from a strong jet stream overhead."

Saturday morning started off stormy across portions of the central Plains as leftover thunderstorm complexes packing heavy rain and gusty winds swept across the region. AccuWeather meteorologists say residents across the region will still need to be wary of more severe thunderstorm threats later in the week.

Thunderstorms on Saturday and Saturday night led to at least 143 separate storm reports, mainly clustered in Kansas and Colorado. Wind and hail were the main modes of severe weather but eight tornadoes were reported as well across Colorado, Iowa, Illinois and Nebraska.

Severe weather continued straight from Saturday into Sunday with at least 176 separate storm reports. This time there were clusters of wind reports in northern Alabama as well as western North Carolina, along with a few wind and tornado reports in Illinois and Indiana.

AccuWeather meteorologists had outlined a large moderate risk of severe weather for Sunday that included a large part of Illinois into parts of Indiana where at least two tornadoes were observed.

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After the tornadoes on Sunday, Illinois is now at 128 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 (NOAA).

The number of flight cancellations is likely to increase through Monday.

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

The same storm system that impacted areas on Sunday 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 and Washington, D.C.

North of the storm track, there was significant rainfall from Minnesota and Iowa into portions of South Dakota.

While there were localized pockets of flash flooding in the region region, the bulk of the rainfall was beneficial as many areas remain in a drought, Anderson added.

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, Indiana, on Aug. 24, 2016. (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 both had 11 confirmed tornadoes on this day with the strongest being an EF3 tornado with winds of 160 mph in Woodburn, Indiana. Fortunately, there were no fatalities reported during the outbreak.

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