The Flathead and Mission valleys are expected to see thunderstorms Saturday that could produce golf-ball sized hail, heavy rain and damaging wind gusts.

According to the National Weather Service, a line of storms was expected to track eastward across Western Montana beginning Friday night into Saturday morning. The storms have the potential to bring wind speeds greater than 60 mph, large hail, lightning and brief heavy rain.

“Our confidence is low in the chance for these kinds of impacts occurring, however with the potential very much in the picture, it cannot be ignored,” the Weather Service warned in its Friday forecast discussion.

Storms will become more widespread and ease in strength and intensity by Saturday morning as more steady-state rainfall begins to fill in across the region.

A cold front moves in after the weekend, with snow possible in some locations on Monday.

“The chance for snow accumulations down to 4,500-5,000 feet is a real concern during this time,” the Weather Service states.

People headed outdoors should be prepared for “raw, cold and wet conditions.” High temperatures in the valley on Monday will struggle to get out of the 50s.

Given that Glacier National Park opens on the west side on June 8, those who plan to go into the Park should plan ahead for unseasonably cold temperatures (on the order of 15 to 20 degrees colder than normal for this time of year), along with brief snow accumulations in the higher elevations of the Going-to-the-Sun Road,” the Weather Service continued.