It's all about timing. The line of severe weather is slowly moving through Montana, and the bulk of the storm could move through the Bismarck-Mandan area during the early morning hours of Wednesday. (6/22)

At publishing time (8:15 p.m.), current radar indicated a severe thunderstorm cell moving northeast from Amidon. The larger system is moving southwest from Montana near Culbertson. This is the larger system, and this is the system that could effect the Bismarck-Mandan area in the early morning hours.

NWS

Areas to the west of Bismarck will feel the effects of this system first. This storm has the potential of producing tornados, strong gusty winds up to 80 mph, dangerous lightning and large hail.

Update- 8:25 p.m.- A severe thunderstorm warning is in effect until 9:15p.m. for Mercer County.

(source)