The summer solstice happened on Friday, June 20th, but apparently the Northern Rockies missed the memo. A cold (relatively) area of low pressure is dropping through the Northwest, creating rain, thunderstorms, and even heavy mountain snow. A winter storm warning is in effect for Glacier National Park above 6,000 feet where 6-12 inches could accumulate in those higher elevation areas. Snow levels could drop as low as 3,000-4,000 ft Sunday morning, causing travel issues on mountain passes over that elevation.
Our in-house model (Baron) shows over a foo of snow in the Lewis Range, which encompasses Glacier National Park in NW Montana, and pockets of 6"+ in SW Montana in the Gallatin Range and the Absaroka Range, in Yellowstone National Park.
Light snow was observed in a few locations Saturday morning, but the bulk of the snow is expected to fall from Saturday night into Sunday morning. A few areas of snow could develop again in the higher elevations late Sunday night.