After a refreshing stretch of cooler weather across much of the Plains and Midwest in recent days, building heat and humidity across the region will provide fuel for thunderstorm development this weekend.
The building heat and humidity across the center and northern tier of the nation is in response to a northward retreat of the jet stream winds, which plays a major role in day-to-day weather. During the summer months, subtle disturbances embedded within the jet stream winds are often responsible for explosive thunderstorm development.
The thunderstorm threat over the coming days will be in direct response to those events.
After thunderstorms rolled across the Upper Midwest Friday night, bringing along heavy rain and locally strong wind gusts to places like Duluth, Minn., AccuWeather meteorologists are shifting their focus a little farther west across the Plains for the threat for thunderstorm development Saturday afternoon.
One of the weak embedded disturbances chugging along through the jet stream will slide eastward out of the Rocky Mountains towards the central Plains during the day on Saturday, and as it treks east of the Front Range, ingredients will come together for severe thunderstorms across the region.
Motorists traveling along interstates 80 and 90 across Nebraska and South Dakota, will want to monitor the sky very closely during the afternoon hours, as thunderstorms can pop up and become severe within a matter of an hour, sometimes less.
While the threat for severe weather is expected to be higher to the east of Sturgis, South Dakota, a feisty afternoon thunderstorm cannot totally be ruled out. With thousands of bikers in the area for the annual motorcycle rally, visitors may want to find a safe place to keep their bike in case rain, hail or wind threaten their vehicles.
Other cities across the Plains at risk for strong wind gusts, hail and localized flash flooding on Saturday include North Platte and Kearney, Neb.; and Pierre, S.D.
Into the evening and overnight hours, the threat is expected to continue eastward. Sioux Falls, S.D.; Omaha, Neb.; and possibly even portions of western Minnesota and Iowa, could be threatened by severe thunderstorms if they can maintain intensity overnight.
The setup for severe weather during the day on Sunday will be somewhat dependent on how the remaining atmospheric energy from Saturday's activity behaves as it tracks eastward through the Midwest. On top of that, there will be another reinforcing disturbance tracking across the Canadian border that could act as another focal point for thunderstorm activity.
As a result, there is an expansive area that could potentially deal with severe weather on Sunday.
Impacts from the expected thunderstorm activity on Sunday will likely be similar in nature to what we expect to occur on Saturday. Damaging wind gusts, isolated reports of large hail and downpours, which could lead to localized reports of flash flooding are all expected to play out within the threat zone.
Cities at risk for severe thunderstorms on Sunday include Eau Claire and La Crosse, Wis.; Minneapolis and Rochester, Minn.; and even cities along the Interstate-29 corridor in the Dakotas.
Conditions will begin to calm down across the Plains and Upper Midwest early next week as an advancing cold front is expected to sweep through the region. In its wake, an area of high pressure is expected to briefly settle in, resulting in quieter conditions.