Winter in August: Montana, Wyoming Brace for Snow, Cold
While much of the U.S. will swelter in heat and humidity this weekend, it will feel more like fall, or even winter, for much of Montana and Wyoming.
An unseasonably cold low pressure system is expected to bring below-average temperatures to the northern Rockies through early next week. Temperatures will be up to 35 degrees below average in some locations this weekend. Glacier National Park may not even reach 50 degrees for a high on Saturday.
In fact, low temperatures will drop below freezing in the higher elevations, leading to the chance for the first snow of the season to fall. In West Glacier, Montana, the average date for the first temperature below 32 degrees is Sept. 13, so the cold conditions are about three weeks ahead of schedule.
There is abundant moisture with this system that will bring rain to the region with snow possible in the higher elevations. There will be gusty winds as well. The cold rain will be heavy at times and enhanced by deepening upslope flow on the eastern side of the Rocky Mountains.
Snow accumulations will generally be a few inches or less, and the snow is expected to melt quickly. Up to 5 inches of snow is possible at the highest elevations through Sunday.
Snow levels will lower to near 6,500 feet in Glacier National Park, with light accumulations possible at Logan Pass. The higher peaks of the Big Horn Mountains in Wyoming could see about 3 inches of snow by Sunday.
Snow has occurred in Glacier National Park in August before. The National Park Service says that in 1992 a foot of snow fell in the northeastern section of the park. Snow has fallen even in lower elevations in August. During the 1992 storm Great Falls, Montana, reported 8.3″ of snow, and the coldest high temperature for the month of August was set at 38 degrees on Aug. 22.
This past June a snowstorm delayed the opening of Going-to-the-Sun Road, a main road in Glacier National Park.
Anyone with outdoor or travel plans this weekend in western Montana and Wyoming should be prepared for rapidly changing and winterlike conditions.
There is another chance of snow Monday and Tuesday as another disturbance moves through the region. Cold mornings will continue through Wednesday with frost likely as well. However, temperatures will moderate by late week and drier weather will return.