A low pressure system in the Gulf of Alaska is poised to settle in over the next few days. Common to what has been recently observed, pieces of energy will break off of this parent disturbance in the Gulf of Alaska and move eastward.
As they move eastward, a ridge of high pressure extending from the Southwest into Canada will force the pieces of energy northward over the high pressure system. As the disturbances move south again after moving over the ridge, they will move south as the high pressure system's influences end.
The jet stream will help to force these pieces of energy south into the Northern Plains and Upper Midwest, where showers and storms may be initiated in the mentioned regions, similar to what is ongoing today (August 4) and what has happened in the past couple of weeks.
Long range forecasts have this low pressure system in the Gulf of Alaska breaking down, but long range forecasts are notorious for being a long ways off of what happens, so take that for what it's worth.