JACKSON, Wyo. – Despite having a wet October, consistent above-average warmth this fall and a dry start to November have resulted in a meager early season snowpack in the Tetons. The snow depth at Jackson Hole’s upper mountain on November 11 is tied with 2011 for the lowest on this date in the last 25 years.
Recent Weather
The past week has featured abundant sunshine, dry conditions, and above-average temperatures across Western Wyoming and Eastern Idaho.
A high pressure ridge over the Interior Western U.S. has been the culprit of this pattern, while the storm track has been centered to our northwest over Washington and British Columbia (more rain than snow for these areas due to mild temperatures).
High temperatures have been in the 50s in the valleys over the past seven days, and even hit 60ºF in town on Sunday and Monday, while lows have been in the low 20s.
So far during the month of November, temperatures are running 6.6ºF above average in the town of Jackson, when factoring in both high and low temperatures.
Here is the 7-day weather summary for the town of Jackson:
For perspective, the average high and low temperatures in Jackson on November 11 are 43º and 20º.
While we have yet to see our first accumulating snow event in the valley, snow coverage is also sparse in the Tetons until you get above 10,000 feet.
Between 9,000 and 10,000 feet, snow coverage exists in north-facing terrain and in shaded areas, while sun-exposed areas below 10,000 feet have little to no snow coverage.
The current snow depth in the sheltered Rendezvous Bowl Plot at 9,580 feet at Jackson Hole Mountain Resort is 6 inches. This is tied with 2011 for the lowest snow depth at this location on November 11 in the last 25 years. The average snow depth for the date is 21 inches.
Early season snowpack data is limited prior to 2000, but based on snow water equivalent data from the Phillips Bench and Togwotee Pass Snotels, the last time we had a lighter snowpack than this in the Tetons was most likely in November 1999, when these locations both had zero snowpack on this date.
We are also still waiting for the first accumulating snowfall of the season in the town of Jackson. The average first snowfall date in Jackson is October 16, so we’re on track to be at least a month behind schedule.
Long-term data (prior to about 2010) has lots of gaps in the town of Jackson, but based on the data that is available, the latest first snow in Jackson occurred on December 3, 2007. Interestingly enough, 2007-2008 turned out to be a huge winter – the snowiest on record for Jackson Hole Mountain Resort’s upper mountain with over 600 inches recorded at the Raymer Plot.
Can we blame the unusually slow start to this year’s snow season on El Nino?
Not necessarily. The other two low early/mid November snow years mentioned (1999 and 2011) were both La Nina years.
Eventually the snow will come, but we’re certainly off to a slow start this year.
Upcoming Weather Pattern
Over the next 7 days, we have two chances for mountain snow, but they will most likely be light events. We may also have to wait at least another 6-7 days before the first snow of the season in the Jackson Hole Valley and the town of Jackson.
Thursday and Friday will be the last two unseasonably warm days with highs in the upper 50s in the valleys.
The first weak storm will then move through on Saturday, bringing light rain showers to the valley and light snow showers to the mountains. Snow levels will generally range from 7,000 to 8,000 feet and high temperatures in the valley will be in the 40s.
Conditions will dry out again on Sunday and Monday, but we should hang onto some partial cloud cover and temperatures will also be a little cooler compared to this week with highs in the upper 40s to low 50s.
The next storm is projected for Tuesday to Tuesday night, but the center of the storm will track well south of our area, so this is also trending toward a lighter event.
A cold front is expected to arrive at some point on Tuesday PM, and as temperatures drop behind the front, there is a chance that we could get our first accumulating snow of the season in the valley.
But it’s not a great chance, as the precipitation event looks light and we may also see a drying trend once the colder air arrives. Still, we’re close to a week away so there is some uncertainty in these details.
The 7-day snowfall projection below represents the average of 50 simulations of the European Model.
The signal is for light snow in the Tetons over the next 7 days, while California and the Sierra Nevada Range will see the most favored storm track where heavy snow is expected.
Utah and Southwest Colorado will also pick up more snow with this southerly storm track, and the Eastern U.S. mountains will also see their first widespread snow of the season.
Looking further out, there are some signs that we could see another storm around November 19-20 with cold enough air in place for snow levels to be on the valley floor. This is probably our best chance over the next 10-14 days of getting our first snow in the valley.
Whether or not this potential November 19-20 storm brings significant snow to the Tetons is highly uncertain this far out.
NOAA’s 8-14 day outlook indicates near-normal temperatures for November 19-25. Near-normal temperatures in late November are going to feel significantly colder than what we’ve experienced in recent weeks.
NOAA also has a slight signal for above-average precipitation in our area, which likely stems from the early portion of this period with greater uncertainty later in this period heading toward Thanksgiving.
Alan Smith, Meteorologist
