JACKSON, Wyo. – After a warm and dry November and early December, it’s finally starting to look and feel more like winter as we head into mid-December. In fact, the pattern between now and Christmas is looking active with consistent snowfall expected.
The National Weather Service in Riverton has issued a Winter Weather Advisory for all of Teton County from 11 p.m. Monday through 11 a.m. Wednesday.
Setting the Stage after missing out on the “big storms”
The pattern began to shift last week as a trough of low pressure took hold over the Western U.S., opening up the “storm door” from the Pacific. So far, we have been on the fringe of the favored storm track and have actually been one of the lesser snowy areas in the Western U.S.
For example, a strong storm last week brought heavy snow to Utah and Colorado, but missed the Tetons to the south. Over the past several days, we have been getting more snow, but not nearly as much compared to the Cascades and Sierra who have or are currently receiving multiple feet of snow.
Even Sun Valley is getting slammed with heavy snow early this week, while the Tetons are seeing more modest amounts in comparison.
Still, we have managed to chip away at our snowfall deficit in the Tetons over the past several days and the upcoming week is looking more promising for snowfall as well.
As of Monday evening, a band of heavy snow was moving through Teton County, including over the Town of Jackson.
Off-and-on snow showers will continue through Monday night with generally light accumulations expected in both the valley and the mountains. Then we will see two more significant storms in the days to follow.
In fact, the National Weather Service in Riverton has issued a Winter Weather Advisory for all of Teton County
Tuesday – Tuesday Night Storm
A large storm will move across the Intermountain West on Tuesday and Tuesday night, and although we’ll be on the northern fringe, we will still see significant impacts as a strong cold front approaches.
Strong south/southwest flow with ample Pacific moisture will develop ahead of the cold front with scattered snow showers in the morning becoming more numerous heading into Tuesday afternoon.
We could see some accumulations in the valley early, but then temperatures will warm up into the upper 30s to low 40s in the valley on Tuesday afternoon with rain potentially mixing in with snow.
The highest impact portion of this storm will occur early on Tuesday evening as the cold front moves through, with a few hours of intense snowfall rates and strong winds expected. Temperatures will also quickly fall to freezing on the valley floor behind the front.
At this time, the cold front is projected to move through between 5-8 p.m. on Tuesday with the potential for whiteout conditions and dangerous travel impacts during the evening commute over Teton Pass as the front moves through.
After a warm day, flash freezing is also possible on valley roadways on Tuesday night as temperatures drop behind the front and black ice could be an issue on Wednesday morning.
Snow amounts from Tuesday through Tuesday night will range from 4-8 inches in the Tetons and 1-3 inches in the valley. On Wednesday morning, backside snow showers will result in an additional 1-3 inches in the Tetons with a dusting to a half-inch in the valley.
A break in the pattern will then occur on Wednesday afternoon and into Wednesday night.
Thursday – Thursday Night Storm
The next storm will arrive from the west on Thursday with snow arriving on Thursday morning and continuing into Thursday night.
This storm will be colder with lower density snow expected as a result. At this time, we should expect around 5-10 inches of new snow in the Tetons and 2-4 inches in the valley with the most significant travel impacts over the pass expected on Thursday evening.
However, snowfall rates and winds will not be as intense during Thursday evening’s commute compared to Tuesday evening.
We will see another break later on Friday aside from some possible lingering snow showers early in the day. The next storm is then expected over the weekend (Saturday night-Sunday), but looks to be on the weaker side at this time.
Looking farther out, we’ll be on the outer fringe of the storm track again early next week with light snow possible, but then we could potentially see a more active storm track over the Northern and Central Rockies in the days leading up to Christmas with better snow potential for Jackson Hole and the Tetons.
Alan Smith, Meteorologist