Updated: Jun 25, 2019
A large area of High pressure denoted by the large "H" above will control the overall pattern across the Northern Plains and Prairie Provinces during the upcoming week. This should keep mostly fair weather throughout the week for the Prairies. The map above depicts a possible solution for Saturday June 29th 2019, with an occluded front and Low pressure near the Alberta/Saskatchewan border and associated severe weather risk.
However, over the weekend, the High pressure will translate east and allow a Low pressure (denoted by an "L") to develop somewhere along the Laramie Mountain Range (Montana/Wyoming region) as shown below. The upper level trough (black L) depicted below will eject onto the North American continent and allow warm Gulf of Mexico air to return to the Prairie Provinces.
Where the surface Low develops and moves will depict which areas will see severe weather. The warm/moist air will bring plenty of instability to Manitoba this weekend (if this scenario verifies), well into the 3000-4000J/kg, which is plenty for severe thunderstorms.
The weekend will need to be monitored closely, if the Low deepens more than forecast and resulting strong forcing can be realized, then some pretty robust supercells could occur in the Northern Plains // Manitoba // Saskatchewan region.