JACKSON, Wyo. – Thanks to a multi-week dry spell along with above-average early winter temperatures, early January snow coverage in the Tetons and Jackson Hole Valley is among the lowest on record during the past 50 years.
However, a more active pattern is set to take hold through the first couple of weeks of January with frequent snow chances expected.
December Dry Spell
During the first 10 days of December, an active pattern took hold with 50-65 inches of snow falling across the higher elevations of the Tetons. Then the pattern shut off completely after that.
During the final three weeks of December, snow totals ranged from only a trace to 6 inches in the Tetons above 8,000 feet. The dry spell has continued into the first few days of January as well.
December and January are the two snowiest months of the year in our area, and to go 3 to 4 weeks with almost no snowfall is highly unusual.
Season-to-date snowfall at Jackson Hole Mountain Resort’s Rendezvous Bowl Plot (9,580 feet) as of January 3 is 128 inches, which is the lowest for this date since 2012 and the second lowest in the past 20 years. By comparison, this location had already received 245 inches of season-to-date snowfall by January 3 of last year.
Jackson Hole’s mid-mountain plot has only received 77 inches of snow so far this season, which is the lowest for this date since 1977.
The town of Jackson received 8.4 inches of snow in December (Cocorahs WY-TT-40), compared to a historical average of 18.1 inches. Season-to-date snowfall in town is only 11.6 inches. By comparison, at this time last season, we had already received 49.2 inches of snow in town!
Temperatures were also mild during the month of December, ranging from 3.2ºF above normal at Jackson Lake to 5.8ºF above normal in the town of Jackson.
Jackson did not experience its first subzero temperature of the season until Christmas morning, with a total of four subzero days during the final week of December. Last year, Jackson had 20 days of subzero temperatures prior to Christmas!
On December 30, unseasonably warmth reached the Teton Range and Teton Valley as a ridge of high pressure strengthened over the Intermountain West. The Driggs Airport recorded a high temperature of 49ºF, which broke a daily record that stood for over 100 years.
However, temperatures were much colder in the Jackson Hole Valley with a high of 35ºF in the town of Jackson and a high of 30ºF at the Jackson Hole Airport.
The reason for the discrepancy is that a temperature inversion was in place over the east side of the Tetons, in which cold/dense air (relatively speaking) had settled into the valley with warmer air aloft, and this inversion did not “mix out” during the afternoon due to stable air, light winds, and a low December sun angle.
Early January Snowpack Update
The prolonged dry spell has taken its toll on our snowpack relative to average. Remember, snowpack is a measure of the amount of snow on the ground at a given time (measured in terms of height/depth of the snow on the ground, or liquid content of the snow), which is not the same thing as snowfall.
As of January 3, the snow depth at Jackson Hole’s Rendezvous Bowl Plot is 36 inches, which is the lowest value since 1980 and the third lowest on record dating back to 1975 (50 years of records). Average snow depth on January 3 is 59 inches.
Snow depth at Jackson Hole’s Mid-Mountain is 24 inches, which is the lowest on record for this date (since 1975). Average snow depth on January 3 is 51 inches.
Snow depth at Jackson Hole’s Base Area is 5 inches, which is the lowest on record for this date (since 1975). Average snow depth on January 3 is 22 inches.
Grand Targhee has a current snow depth of 47 inches at its Snotel site at 9,260 feet. Records at this location only go back to 2008, but this is the lowest value on record for January 3.
In terms of snow water equivalent (the amount of water contained in the snowpack), the situation doesn’t appear quite as dire (but still pretty bad) with the Snake River Basin which includes the Tetons reporting 63% of average snowpack.
Nearly the entire Western U.S. is facing a similar snowpack deficit as of early January.
Snowier Pattern Ahead
The dry spell that has taken hold across our area for the better part of a month is finally about to end as high pressure breaks down across the Western U.S.
Over the next couple of weeks, storms will track across the Western U.S. with more regularity, and cold air will also arrive from the north with below-normal temperatures expected through mid-month. Storms will be on the weaker side initially but are expected to trend stronger over time.
The first weak storm will bring snow showers to the area on Thursday and Friday. Snow showers will be terrain-driven (also known as orographic) in nature and will favor the west side and upper east side of the Tetons with only minor accumulations in the Jackson Hole Valley.
Another storm will pass south of our area on Saturday and Sunday, and we will likely only see some light snow showers on the northern fringe of this storm.
Next week, a stronger storm is possible around January 9-10 (depending on the exact storm track) with the potential for more widespread snow.
Here is a snowfall projection over the next seven days, which represents the average of 50 simulations of the European weather model.
Cold air is also going to arrive from the northwest in this pattern, and this will result in dry and powdery snow quality, unlike some of the storms we saw early this season that were warm and wet.
High temperatures during the next week will generally be in the 20s in the valleys and teens in the mountains (~9,000 feet) with lows in the single digits, and possibly subzero during clear periods in between storms.
Looking further out, the door will remain open to additional storms heading into mid-January as the dominant storm track is expected to shift northward into the Northern Rockies.
Alan Smith, Meteorologist
