Field Report (November 22, 2017)

It’s important to know the history of the layered mountain snowpack if we want to understand the avalanche problems that threaten us and recognize the ever changing danger we face travelling in the backcountry. I’d like to be out on the snow, in the area I plan to ski, on a regular basis from the first snows of Fall until late in the Spring. That isn’t always possible; you may not be able to get into the backcountry often enough to observe every storm cycle. You may want to travel to a destination with a very different snowpack than your home range.

I’m writing this report from my annual November getaway spot on the Mexican Riviera. We’re getting ready to celebrate Thanksgiving with tacos and Corona beer. Fortunately I can maintain some connection to the changing snow back in Colorado’s Front Range Zone using SnoTel. The USDA created the SnoTel automatic monitoring network to measure weather and moisture accumulation in the western mountains. The information was collected for the benefit of water planners and highway safety but we can also use the same data to keep a watch over snowpack remotely.

The chart  shows the snow accumulation from November 1, 2017 through November 23, 2017 at the Bear Lake trailhead in Rocky Mountain National Park (SnoTel site 322). We can see that at the start of the month snow from October had melted out completely. A big storm came through on November 7 and deposited nearly two feet of light new snow. Winds after the storm created slabs thick enough to bury a skier (see 20171111 Field Report). For ten days after the storm the Front Range was enjoying mild temperatures and the snow & wind slabs from 11/7 settled down.

This past Friday & Saturday a small storm brought an additional 4 inches of snow to the Bear Lake area. In the days after the storm the winds in RMNP have been severe to extreme according to guides in the field. It’s reasonable to expect that any snow available for transport from westerly slopes has been moved onto east facing zones creating a second layer of wind slabs on those slopes.It looks like the warm and dry  days will be coming to an end after Thanksgiving. Hopefully there will be some new snow in the forecast.

This alternating pattern of snow followed by extremes of wind and warm is a characteristic of the Front Range zone and much of Colorado. Last season was an unusual year for us in Colorado with only a single avalanche fatality. This year is shaping up to be much more dangerous.

CMS Guide: Thomas White