JACKSON, Wyo. – November has been very mild across the region so far, but a storm arriving from the north will bring winter conditions to the entire state of Wyoming just in time for Thanksgiving.
Jackson Hole and the Tetons
A cold front approaching from the north will slow down as it encounters the mountain ranges around Yellowstone. A band of snow developing ahead of this front will move into the Tetons and Jackson Hole on Wednesday night and Thursday morning with accumulating snow for both the higher terrain and the valley.
Periods of snow will continue into Thursday afternoon as the cold front moves through before tapering off to flurries on Thursday evening.
Snowfall from this storm will range from 3-8 inches in the Tetons and 1-3 inches in the valley, but confidence in the snow forecast is lower than usual.
The wind direction will primarily be out of the east/northeast which is typically not favorable for the Tetons, but converging winds near and along the cold front and support from the jet stream will help to counteract this at least somewhat.
Winter driving conditions can be expected over Teton Pass from Thursday morning through Friday morning. Thursday PM will feature strong winds and the potential for blowing snow, while Friday AM will likely feature slick roads as temperatures will be colder and any wet spots on the roads will turn to ice.
Statewide
The storm will impact the entire state of Wyoming as it moves from north to south over the course of the day on Thanksgiving. Lingering snow will also persist across Southern Wyoming and along the I-80 corridor into Friday.
Easterly winds will favor areas along and east of the Continental Divide with the heaviest snow during this storm. This includes the Absaroka, Wind River, Bighorn, and Laramie Ranges, and lower elevations throughout Central and Eastern Wyoming will see accumulating snow as well.
Winds will also be strong during this event with significant travel impacts expected for central and eastern portions of the state on both Thursday and Friday. Travel across the state is not recommended on either day.
Here is a snowfall projection for the Rockies from Wednesday night through Saturday. This model picks up on moderate snowfall for the Tetons and Jackson Hole, with heavier snow across Central and Eastern Wyoming.
After the Storm
Dry conditions will resume behind this storm heading into the weekend. However, the noticeable change is that much colder air will filter in behind this storm with consistent winter temperatures taking hold.
November has been warmer than average so far, but starting this Friday and continuing through the end of the month, temperatures are expected to be below average.
What this means is that high temperatures will generally be in the teens to 20s depending on elevation with overnight low temperatures falling to near zero in the valleys.
It’s also possible that temperature inversions will persist into the afternoon hours if we manage to see some snow cover in the valley, in which case high temperatures may end up colder (teens to low 20s) in the valley than in the mountains.
Temperature inversions occur when the atmosphere is stable, skies are clear, and winds are light. This allows cold, dense air to sink to the lower elevations overnight, and in early to mid-winter when daylight is limited, inversions often persist through the afternoon hours in Jackson Hole. This is especially true once there is snow cover in the valley, as snow cover reflects solar radiation back into the atmosphere.
What about snow potential? Unfortunately for skiers, the pattern is going to dry out again through at least the end of November. There are some hints that we may start to transition into a more active pattern in early December, but confidence is low as this is more than 10 days out.
Hope everyone has a Happy Thanksgiving and stay safe out there on the roads!
Alan Smith, Meteorologist
