It may only be Tuesday, but the National Weather Service in Great Falls has already issued a pre-emptive Winter Storm Watch for areas along the northern Rocky Mountain Front this weekend.
The Watch will go into effect at 6 p.m. on Friday, September 27, and runs through 6 p.m. on Sunday, September 29.
The affected areas include Glacier, Toole, Pondera, Teton, and northern Lewis & Clark Counties; the NWS says that the Watch will likely be expanded further east and south with future forecast to include more of the North Central Montana plains.
The Winter Storm Watch states: "Blizzard conditions possible. Total snow accumulations of 18 to 36 inches, with locally higher amounts in the mountains. Record or near-record temperatures in the teens and 20s with wind chills zero to 15 above zero. North to northeast winds 15 to 25 mph with gusts as high as 40 mph."
Impacts: Extreme impacts possible, including to power infrastructure including power lines resulting in widespread power outages, agricultural interests; outdoor recreational interests including camping and hunting activities; and travel. Widespread significant tree damage is possible with heavy wet snow and strong winds impacting trees with foliage. * additional details.
This early-season winter storm and/or blizzard has the potential to set a new benchmark for snow accumulations, cold temperatures, and resulting impacts for parts of the Northern Rockies and the Rocky Mountain Front. A similar storm in 1934 produced prolific amounts of snow in late September over north-central Montana. An extension and/or expansion of winter storm watches are likely.
The NWS says that confidence is high on possible accumulations, winds, and expected impacts. There is low to moderate confidence on the timing of onset and end of this winter storm event.