JACKSON, Wyo. — A powerful storm will impact Northwest Wyoming this week, resulting in significant snow accumulations from Monday through Wednesday along with strong winds. Following this storm, an arctic cold front will arrive, ushering in some of the coldest air we’ve seen in the past few years on Thursday and Friday.
Recent Weather Recap
Last week featured a cold and unsettled pattern with light snow accumulating in the Tetons on a frequent basis. Moisture in the atmosphere was primarily confined to mid to upper mountain elevations, and terrain-enhanced lifting of this moisture resulted in several rounds of snowfall.
As of Monday morning, seven-day snow totals have ranged from 6-14 inches in the Tetons and 3-4 inches in the Jackson Hole Valley.
Snow totals for the month of December so far (as of December 19), include 76 inches at Jackson Hole Mountain Resort’s Rendezvous Bowl Plot, 55 inches at JHMR’s Mid-Mountain Plot and 43 inches at Grand Targhee. The Rendezvous Bowl Plot averages 90 inches of snow for the month of December as a whole, so we are on pace for an above-average snowfall month.
Snow totals for the month of December across the lower elevations so far include 28 inches in Moran, 28 inches at the JHMR Base Area, 22 inches at Snow King, and 14 inches in the Town of Jackson. The Town of Jackson averages 18.1 inches of snow for the month of December as a whole.
Temperatures were very cold this past weekend with three days in a row of lows in the teens below zero in Jackson from Friday to Sunday. So far this month, temperatures are running 5.7 degrees below normal in Jackson.
Forecast for Monday (12/19) to Sunday (12/25)
A storm will arrive from the northwest early this week and result in a long-duration snow event from Monday afternoon through Wednesday afternoon. The National Weather Service in Riverton has issued a Winter Storm Warning for all of Teton County from 11 p.m. Monday through 11 p.m. Wednesday.
Light snow during the day on Monday will give way to more widespread snow with increasing snowfall rates on Monday night and Tuesday. Heavy snow can then be expected on Tuesday night and Wednesday and strong winds will also develop ahead of an approaching arctic cold front.
Snowfall will eventually come to an end by early Wednesday evening with blustery winds continuing on the backside of the storm.
Snow totals from Monday through Wednesday evening will range from 10-20 inches in the Tetons and 4-10 inches in the Jackson Hole Valley, as well as Teton Valley.
Travel conditions will gradually deteriorate through the day on Tuesday, then will become very poor on Tuesday night and throughout the day on Wednesday as heavy snowfall rates combined with strong winds will result in blowing snow, drifting snow and near whiteout conditions in open areas. Road closures will be a possibility in the most exposed areas.
Once the snow comes to an end, an arctic cold front will arrive on Wednesday evening. Behind this front, some of the coldest air we’ve seen in quite some time will arrive on Thursday and Friday.
On Thursday, high temperatures will remain below zero at all elevations. On both Thursday and Friday mornings, lows will drop into the minus 20s in the valley.
The last time the temperature dropped to -25ºF at the Jackson Hole Airport was in February 2020. The last time it got colder than that was in January 2017 when it dipped to -29ºF. We will likely see low temperatures right around these values on Thursday and/or Friday mornings.
Heading into Christmas weekend, we will see a gradual warm-up occur. The warm-up will happen first in the mountains as an inversion sets up with warmer air aloft. The warm-up in the valley will be more delayed, though by Christmas Day, we should see more tolerable values as the inversion is expected to weaken.
A couple of minor disturbances will also brush the area between Friday and Sunday, which could result in some occasional light snow showers. Confidence is low, however.
The week between Christmas and New Year’s looks milder in terms of temperature but also more active in terms of snow chances. It looks like the next storm will arrive around December 27-28 with additional storms possible through the end of the year.
Alan Smith, Meteorologist
Town of Jackson Climatology for December 19-25:
Average High: 28
Average Low: 6
Record High: 55 (December 21, 1933)
Record Low: -52 (December 20, 1924)
Precipitation Since Oct 1st: 3.92″ (106% of average)
Town Snowfall Since Oct 1st: 39.6″
Rendezvous Bowl Snowfall Since Oct 1st: 190″
Rendezvous Bowl Snow Depth: 49″