Over the last few weeks, we have seen several cold Fall storms that delivered snow to Alberta, British Columbia, and every state in the Western US except for Nevada (we think?). It's exciting to see September snow throughout the region, with some solid accumulations in British Columbia, Colorado, and New Mexico.
One part of this this post will be a discussion on additional snowfall events that are possible in the next few weeks. The second part of the post will get into why as we get further into Fall, we dread significant snowfall in our mountains. There are two storms we are tracking in the next two weeks, and both have the potential to bring accumulating snow to a large swath of the West. We can tell you right now that as much as we love seeing snow, we do NOT want significant accumulations this time of year.
Potential Snowstorms
So we're going to keep this discussion pretty short, and just provide a few details about the upcoming chances for snow. The first system will impact much of the West between Tuesday and Friday. Once again, this system will bring below normal temperatures to the region, as well as significant moisture much of which will fall as snow. We have high confidence in this storm impacting the region, and one of the ways we gain that confidence is by looking at the upper level pattern in the model ensembles. You can see the upper level pattern forecast from the American, European, and Canadien models are quite similar in the gif below. This gives us confidence in the storm and its track.
(Image courtesy of Weatherbell)
The models are consistent in terms of the temperature forecast as well. In the next gif, you can see below normal temps, indicated by the blue/green colors, moving into the Pacific Northwest on Tuesday and then continuing to move inland through the latter half of the week.
(Image courtesy of Weatherbell)
You can also see the most below normal temperatures in the Sierra, and that's where the greatest potential for snow is as well. The coldest temperatures overall, however, will be in Washington and BC. Southwest Montana and Western Wyoming have a decent shot at accumulating snow as well. And here is the American model's ensemble snowfall forecast through the end of the week, showing the greatest potential for snowfall in the Sierra, the Uintas, and the Tetons.
(Image courtesy of Weatherbell)
The second storm on the horizon looks to arrive around Sunday and could last through Wednesday. Once again we will look at the upper level pattern in the ensembles.
(Image courtesy of Weatherbell)
Although each of the ensembles shows a storm moving into the Northwest, the exact location and timing does vary between models. This is expected this far away from the event, but gives us less confidence in the finer details. We expect another storm system, again with cold enough air, and significant enough moisture, for accumulating snow. This storm could also bring widespread low elevation snowfall, but it is too early to get more specific. For now, that's all we'll say about that.
We Don't Want More Snow, Right Now...
While August and September snow is exciting and often scenic, once we get into October we actually hope that the mountains in the Western US and SW Canada do NOT see substantial snowfall. We fear significant snowfall during this time because of the potential snowpack problems that can result from the early season snow. With snowfall events during September, October, and November, there is often a return to warmer Fall like weather, or at least an extended period with out additional snowfall before the winter weather patterns establish themselves. If it snows enough that it doesn't all melt, and there is a long break between storms, the snowpack begins to weaken. This can lead to an unstable snowpack that can persist throughout an entire winter. The dreaded persistent weak layer (pwl). So, as much as we love seeing snow, let's hope the accumulations remain on the lighter side, so that even the upper elevation shaded northerly aspects melt quickly. With the current drought status across the West, we have a competing need for precipitation though. The best solution is for precipitation to fall, but remain in liquid form. As always, we urge everyone recreating in the mountains in the Winter to take an avalanche course, and one great place to do so is with Selkirk Powder.
So let's hope for (not that much) snow from the next couple storms, and instead save it for November through April.
Announcement: Promotion for our concierge program- Anyone that renews or signs up prior to September 30th will receive a bonus forecast at no extra charge prior to December 15th. This is in addition to the normal custom forecasts.
Luke (@lstone84 on Instagram)
