In an unusual weather phenomenon, the high-elevation areas of the Montana mountains are bracing for an unexpected bout of wintry conditions just days before the summer solstice. While the Midwest and East Coast are preparing for a potentially historic heat wave, the Western parts of the United States are set to experience colder temperatures and threats of accumulating snow.

A cold upper-level low is making its way through the Pacific Northwest and is expected to move into the Intermountain West early next week. Seattle and Western Washington will be the first to feel the effects of this cool air mass, as thunderstorms and temperatures struggling to reach the 50s are forecasted. Snow levels in the Cascades are predicted to drop to around 3,000-4,500 feet, resulting in wet snow for hikers and potential accumulation on higher peaks.

As the cold air spreads eastward, Frost Advisories have been issued for a substantial portion of Eastern Washington and northern Idaho on Sunday morning. The advisories warn of temperatures dropping into the low to mid-30s, posing a risk of damage to sensitive crops and plants.

The upper-level low is expected to settle into western Montana at the beginning of the workweek, bringing with it the potential for heavy snowfall in the northern Rockies. Winter Storm Watches have been posted for large areas of the Montana mountains from Monday into Tuesday. The forecast predicts 1-3 inches of snow for Lost Trail Pass, 3-6 inches in the Sapphire and Bitterroot ranges, and the possibility of 6-14 inches above 6,000 feet in Glacier National Park. Remarkably, this marks the sixth June since 2005 in which Montana has seen Winter Storm Watches, according to Iowa State University's Iowa Environmental Mesonet.

However, this unseasonable chill is expected to be short-lived, with long-range forecasts indicating a quick return to seasonal averages by the end of the week. Additionally, there is the looming potential for hot weather after the upcoming weekend.

As summer approaches, residents and tourists in the higher elevations of the Montana mountains are advised to prepare for unexpected snowfall and to take necessary precautions while enjoying the great outdoors.