Severe weather to invade northern Plains, southern Canada into Monday

By Kyle Elliott, AccuWeather meteorologist

June 10, 2018, 11:40:55 AM EDT

A vigorous storm system bringing unseasonably cool and unsettled weather to the Pacific Northwest this weekend will trigger an outbreak of severe weather across south-central Canada and the northern Plains.

The storms will erupt as summerlike heat and humidity being drawn northward from the Gulf of Mexico clashes with March-like air plowing eastward through the northern Rockies this weekend.

By later Sunday afternoon, the first round of storms will be getting underway and is forecast to begin just west of Saskatoon and Regina, Saskatchewan, to the border of North Dakota and Montana and just east of the Black Hills of South Dakota.

“While a tornado cannot be ruled out across parts of the Dakotas, the greatest threat for tornadoes will be into Canada, from Regina to Saskatoon,” AccuWeather Meteorologist Brett Rathbun said.

The highest probability of tornadoes typically occurs within the first couple of hours of storm formation, and this case should behave no differently.

“As the individual cells merge into a squall line, damaging winds will become the primary threat during the evening hours as it pushes eastward, impacting cities such as Bismarck, North Dakota,” Rathbun said.

In addition to tornadoes and damaging winds, large hail and brief torrential downpours are also on the table.

Although flash flooding would typically be a concern in this type of setup, that risk will be minimized since much of south-central Canada and the Dakotas remain in a moderate to severe drought and need the upcoming rain.

“However, travel along Interstate 94 may become difficult, and drivers are urged to reduce speed in any heavy downpour,” Rathbun said.

The risk of hydroplaning increases dramatically on wet roadways when traveling at highway speeds.

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Check the AccuWeather Severe Weather Center for the latest national weather alerts

In addition, residents in the path of Sunday’s storms should be prepared for power outages, as well as tree and property damage.

Move vehicles inside a garage or other shelter when violent storms threaten to avoid windshield and window damage from destructive hail.

For those with outdoor plans such as fishing, biking, jogging, swimming or golfing, make sure to stay abreast of the latest severe weather alerts and be in a position to move indoors quickly at the first clap of thunder since lightning is then close enough to strike.

By Monday, an area stretching from southern Minnesota to eastern Kansas and northern Missouri lies at risk of violent thunderstorms.

Cities such as Omaha, Nebraska; Des Moines, Iowa; and Kansas City and Topeka, Kansas, all may lie in the path of Monday’s storms.

All modes of severe weather, much like Sunday, will again be possible on Monday.

Large portions of interstates 29, 35, 70, 80 and 90 lie within Monday’s threat zone, so motorists with travel plans should be prepared for significant travel delays and turn around if they come across flooded roadways.

As the storm system responsible for the multi-day span of severe weather moves into the Ohio Valley by midweek, it will lose much of its energy and only produce hit-or-miss showers and storms in these areas.