JACKSON, Wyo. – Snowpack in the Tetons is only about 50% of average for mid-November as recent stronger storms have been missing our area to the north and to the south. Snow is in the forecast on Friday and again on Monday, but a dry spell looms later next week.
Recent Weather
November is off to a chilly start with temperatures running 2.9 degrees below average in Jackson through the first 13 days of the month. We have picked up some snow this month, but this pattern has not translated to heavy or consistent snowfall.
The large-scale pattern has been active for the Western U.S. as a whole with frequent low pressure systems, while the Eastern U.S. has been dominated by high pressure ridging and warmer and drier than normal conditions.
Despite the “storm door being open” in the West, the Tetons have been unlucky when it comes to snowfall…
Storms in the West in recent weeks have typically behaved in one of two ways…
- Strong storms originating in the Gulf of Alaska have produced heavy snow in the Cascades and British Columbia, but winds aloft blowing from the south/southwest have kept most of the moisture and energy from these storms well north of the Tetons.
- Numerous storms have also impacted the Northwest before quickly diving southeast into the Four Corners region, before stalling for multiple days and producing heavy snow in New Mexico and Colorado. We have only been brushed with light snow by most of these storms.
Several storms in the past few weeks have produced snow in the Tetons, and even a little bit in the valleys. But the storm tracks have not been favorable for significant, base-building snow.
Current snow depth around 9,000 feet in the Tetons ranges from 6 to 11 inches at Jackson Hole Mountain Resort and 15-17 inches at Grand Targhee. These values are about 50% of average for November 13. At 8,000 feet, only a few inches of snow are on the ground.
The 11-inch snow depth at Jackson Hole’s Rendezvous Bowl Plot is the lowest for this date since at least 1998 (when daily snow data was first regularly reported in November). At Targhee, this is the shallowest November 13 snowpack since at least 2007, when records began.
In the chart below at Grand Targhee, the green line represents the median (average) snowpack (measured by snow water equivalent) over the course of the season, while the blue line shows the historic maximum snowpack for a date, and the red line the historic minimum snowpack for the date dating back to 2007.
The black line represents the current snowpack, which is right at the historical minimum over the past 18 years.
If you’re a skier or snowboarder, there is no need to panic. It is only November 13 after all, and a deep storm cycle or two later in November or December could quickly turn things around. Of course, persistent weak layers forming in the shallow snowpack could be a concern down the road from an avalanche danger perspective.
Upcoming Weather Pattern
If you like snow, there is good news and bad news in the upcoming weather forecast…
The good news is that two storms are heading our way within the next week.
The first storm will be relatively weak in terms of atmospheric dynamics but will tap into some decent moisture and will have a favorable track from southwest to northeast across the Sierra Nevada Range and into Northwest Wyoming.
This storm will impact the area from Friday night to Saturday afternoon with moderate snowfall totals expected in the Tetons. Light accumulations will also occur in the valley. Saturday morning will be the highest impact travel period with slick and snowpacked roads, though winds are expected to be light which will limit the potential for blowing snow.
The second storm will approach our area from the Pacific Northwest and will impact the Tetons and Jackson Hole sometime in the Sunday night to Monday night timeframe. Cold air will be arriving with this storm and this will likely result in a low-density, powdery snow event.
Moderate snow totals are also anticipated with this second storm, but we’re still far enough out that the storm could trend stronger or weaker for our area. For now, travel impacts look like a good bet during both the Monday morning and Monday evening commutes, with lingering impacts likely on Tuesday morning.
The image below shows projected snowfall over the next 7 days, representing an average of 50 simulations of the European weather model. The storm track will continue to favor the Northwest U.S. and Canada, but the Tetons will pick up some respectable snowfall as well.
Now, for the bad news if you’re a fan of snow…
Confidence is growing that a strong ridge of high pressure will build over the Western U.S. in the wake of Monday’s storm, and this could potentially lead to an extended dry spell.
Temperatures will start out cold at the onset of this pattern next Tuesday-Wednesday (November 19-20), but will trend warmer over time… at least in the mountains. It’s possible that a temperature inversion could keep high temperatures colder in the Jackson Hole Valley compared to the mountains, depending on valley snow cover (more snow cover supports stronger inversions).
Long-range models are projecting this dry spell to persist through at least November 24, and possibly even longer. But forecaster confidence is inherently lower beyond 7-10 days out, so perhaps the dry spell won’t last for as long as feared.
Regardless, low snowpack in November is easier to bounce back from, compared to say, January or February. If a snowy December were to occur, it could quickly set us on the path toward a strong winter.
Seasonal forecasts are fun to look at, but they are not particularly reliable and contain an inherent level of uncertainty. We are heading into a weak La Nina this winter, which as you may have heard, is correlated to above-average snowfall in the Tetons historically.
While that may sound encouraging, there are many other atmospheric and oceanic factors that cannot be predicted far in advance the way La Nina and El Nino can, so it’s always important to take seasonal outlooks with a grain of salt as it can really go either way.
Alan Smith, Meteorologist
