Winter storms, large and powerful, often strike the North of the country throughout Winter. Canada begins to see their first big winter storms during October. However, it’s not very often that the U.S., even in the North, gets a big winter storm at the end of September, however that is what we have to contend with for this weekend.
The forecast:
Conditions are expected to worsen across higher parts of the Northern Rockies, higher parts of Washington state and higher parts of Oregon (above 1,500ft) as early as Saturday. 5-8″ of snow is expected on higher ground here with a mixture of heavy rain and intermediate sleet to lower elevations.
By Sunday, the system will have progressed south, but only at slow rates. It will still be affecting the same areas it was on Saturday, however will have extended snowfall into much of the northern Rockies range, with higher parts of Idaho, Nevada and north west Wyoming. Montana will also continue to be affected, however here things are a little more complicated. For the WESTERN HALF of Montana, on Sunday the precipitation will largely remain as snowfall, especially with altitude. However for the EASTERN HALF, a mixture of sleet is more likely.
However, by later on Sunday and into Monday, the majority of Montana will likely experience snow & sleet, with significant accumulations likely. Some of the worst affected areas could see in excess of 12 inches from this storm. Winds will also be very strong, producing a high risk of drifting snow, especially in high elevation areas where the snow will have a lower moisture content, and be drier as a result. To lower ground, there is a risk of power outages due to wet snow which could accumulate in the order of 6 to 12 inches in places.
Wind chill will also be severe in places. By Tuesday, the system will begin to transfer to the North East of Montana / the northern Rockies, leaving just some residual flurries, however northern Montana could still see moderate snowfall of 1-2 cm (0.5 to 1 inches) per hour. As the storm tracks north east, it will dump 2-3 inches of snow widely for central parts of Canada early next week, however should be fairly swift to exit the U.S. It can’t also be ruled out that on higher elevations in Montana and the Northern Rockies, totals could approach 2 feet (24 inches). Needless to say, this is a VERY early system and has the potential to cause a serious amount of disruption. Stay tuned very closely to local weather updates for any possible changes to the track.
Estimated snowfall accumulation – GFS model (via meteociel.fr).
