Sunday, March 27, 2011

Jackson Hole Terrain, Weather, and Climate

JH, 26 March 2011
Being a certified Utah terrain and powder snob, I don't leave the Wasatch very often to ski elsewhere, but crossed the border for a fantastic day of late season skiing at Jackson Hole (JH) on Saturday.  In addition to my son Erik, my partners for the day included two of the best mountain weather meteorologists out there, Jim Woodmency, a Jackson icon who provides forecasts for several of the local radio stations and runs, and Jamie Yount, a Utah Meteorology alum who does avy control on Teton Pass.  Jim and Jamie also offer a winter weather forecasting class through the American Avalanche Institute that I hear is top notch.  Keep an eye out for future offerings.

With a good day of skiing to stimulate the senses, I thought I'd take this opportunity to talk a bit about the weather and climate of JH.  Let's begin by putting the resort into its proper topographic context.

Geographic setting and topography

JH is located on the eastern (lee) side of the Tetons and rises abruptly from the plain of Jackson Hole (see above).  In terms of ski terrain, JH is about as good as it gets and is one of the few mountains that delivers the goods promised by all the marketing.  The most radical skiing is on the upper mountain, but there is great fall-line skiing for essentially the full lift-served vertical.

Although not as radical as the upper mountain, even the lower
slopes of JH offer up a solid pitch.
Much of the terrain at Jackson faces east or even southeast.  This is perhaps an advantage during the heart of the cold Teton winter, but can be a disadvantage during the late season, especially at lower sun-sensitive elevations.  Fortunately, conditions held up well on Saturday.

Long-Term Climate

At JH, Altitude is Everything.  Being a lee-side resort with huge vertical means that there is a massive difference in snowfall between the upper and lower mountain.  Long-term climate statistics from nearby Moose, WY, suggest that the average snowfall at the base is probably a shade under 200 inches.  Long-term snow-safety observations of snowfall at about mid-mountain (8250 feet, source suggest an annual snowfall of about 370 inches, which is pretty good for a North American ski resort, but is lower than the almost 500" that falls at a comparable elevation in Little Cottonwood Canyon.  I don't have long-term climate statistics for the upper mountain, but numbers approaching 500 inches near the summit are likely.  These are solid numbers, although not as strong as Alta-Snowbird.


The large climatological contrast in snowfall between the upper and lower mountain is reflected in the current snow depths measured by automated sensors on the mountain.  There is currently about 40 inches of snow at the base, 115 inches at mid mountain, and 140 inches in Rendezvous Bowl (see grey lines below, note scale change).

Source: Jackson Hole Mountain Resort and MesoWest
It has been a great year for snow at JH, and the resort reported last week that the snow depth in Rendezvous Bowl was a record for that time of year.  This is a non-scientific observation, but an important indicator of a good snow year are partially buried trail signs.

Partially buried signs at the top of the Bridger Gondola
Dendritic Observations

The best snowflake I've observed this year fell not in Utah, but at JH on Saturday.  See for yourself.

Check out that stellar dendrite
When the temperature and relative humidity are right, you can get a stellar dendrite anywhere in the world.  Utah doesn't have the corner on these beauties, and JH gets them in spades too.  

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