JACKSON, Wyo. – An arctic cold front will move through Wyoming on Friday, ushering in the coldest temperatures of the season by far. The frigid airmass will stick around for several days or more with minus 20s possible in the Jackson Hole Valley on the coldest mornings.
Recent Weather
The first seven days of January were active with new snow reported in the Tetons each morning.
The period from January 8-15 was not as active, though we did see an impressive storm on January 11-12, followed by a few snow showers on January 13-14.
Snow totals from the January 11-12 storm included 17 inches at Grand Targhee and 9-14 inches at Jackson Hole Mountain Resort. The town of Jackson only received 2.5 inches of snow and Snow King received 3 inches.
Snowpack has leveled off a bit since last week, and we are now 91% of average in the Upper Snake River Basin compared to 98% of average at this time last week.
Temperatures have been colder over the past week with subzero temperatures recorded in the town of Jackson on three mornings (January 8-10). However, we have not experienced any true cold snaps yet this season.
Halfway through the month of January, temperatures are running 3.4ºF above normal in the town of Jackson.
However, this will soon be changing in a big way…
Upcoming Weather Pattern
The pattern will largely remain dry over the next week with only some light snowfall potential on Friday. The big story will be the arrival of frigid temperatures as arctic air spills southward and overspreads the Continental U.S.
The arctic front will move through Wyoming from north to south during the day on Friday, with snow showers and gusty winds developing.
This system will be moisture-starved with snow amounts ranging from 1 to 3 inches in the Tetons and 0.5 to 1.5 inches in the JH Valley.
Areas east of the Divide in Wyoming will see higher totals with favorable upslope easterly winds developing behind the cold front. This includes the Bighorn Range and the east side of the Wind River Range.
Behind the front, arctic air will work its way into Wyoming with noticeably colder temperatures beginning on Saturday, while temperatures will trend even lower in the Sunday to Tuesday timeframe.
At a larger scale, this will be an impressive arctic blast with subzero cold overspreading significant portions of the Lower 48 by early next week. Wyoming, of course, will see some of the coldest temperatures of all thanks to our high elevation and northerly latitude.
The Jackson Hole Valley will see low temperatures plummeting into the minus teens at least on clear/cold mornings in this pattern, while minus 20s are even possible on the coldest mornings.
The European Ensemble Model (an average of 50 simulations of the European Model) projects a bone-chilling low of -28ºF in Jackson on Monday morning with well below zero temperatures statewide.
Arctic air is very dense and therefore shallow by nature. As a result, arctic air tends to sink to the lower elevation terrain. The most extreme low temperatures during arctic cold snaps typically occur in mountain valleys and basins rather than on the higher peaks.
However, even though low temperatures will not be as extreme in the mountains compared to the valleys, it will still be very cold at all elevations in this pattern. Subzero readings will occur in the mountains including the higher terrain of ski resorts, while highs will struggle to reach the single digits above zero.
If you have skiing or outdoor plans this weekend, be sure to dress in extra layers and wear face coverings (such as a buff) to protect yourself from frostbite.
Other than Friday’s light snow event, snowfall potential is minimal over the next 7 days aside from some occasional flurries.
The Eastern U.S. and even parts of the Southern U.S. will be favored for snowfall this week, with drier conditions for the Western U.S.
Looking further out, temperatures should gradually start to moderate around the middle of next week, at least in the mountains. You may find some relief from the bitter cold as you head up in elevation once this occurs.
However, for as long as the pattern remains dry, an inversion will keep frigid air locked into the Jackson Hole Valley with only modest improvement expected after the coldest days from Sunday to Tuesday.
In terms of snowfall potential, there are some hints of a storm arriving at the end of next week, around January 24-25. However, this is about 10 days away so confidence is low.
Also, it’s unclear at this time whether or not we will head into a more active pattern with higher snowfall potential beyond the 25th, or if we will revert back to a dry pattern with high pressure re-building over the West Coast.
Alan Smith, Meteorologist
