Good morning. This is Dave Zinn with the Gallatin National Forest Avalanche Forecast on Thursday, January 20th at 7:00 a.m. Today’s forecast is dedicated to Tyler Stetson. Tyler was killed in an avalanche in Beehive Basin on this day fourteen years ago. This forecast does not apply to operating ski areas.
This morning, mountain temperatures are in the single digits to mid teens F with west to southwest winds averaging around 10 mph with 20 mph in the Bridger Range. Most areas picked up an additional trace to 1” of new snow yesterday morning before the storm passed. Today, temperatures will rise to around 20 F across the advisory area and around 30 F in the Bridger Range. Winds will be 10-20 mph from the west before increasing tonight and snow will begin to fill in during the late morning hours with 4-6” falling by tomorrow.
The snowpack is generally stable other than small, surface-level instabilities created by yesterday’s 1-3” of new snow. Yesterday, skiers noted relatively small and harmless slabs up to 5” deep predictably breaking near ridgelines where winds formed small drifts. Today, these could be a problem in steep or technical terrain where they could knock you off your feet or sled but would be unlikely to bury a skier or rider. The danger associated with these small avalanches will increase if snowfall intensifies this afternoon.
Beyond these superficial instabilities, keep the fundamentals in mind. We have a layered snowpack and as Ian found in the Flanders drainage on Tuesday, there are isolated areas of instability in a sea of overall stability (video). Assess the snowpack with a pit and a quick stability test to make a slope-scale forecast before entering avalanche terrain. If you are surprised by less stable results, dial your objectives back as Ian did in Hyalite.
Finally, we have a new weak layer buried under a few inches of snow in the Southern Madison and Southern Gallatin Ranges and the Lionhead and Cooke City areas that will likely become a problem as it gets buried deeper. Ian found this stripe of feathery surface hoar buried in the Taylor Fork yesterday, Alex and Doug saw it in Cooke City and at Lionhead earlier in the week and skiers and riders have sent in observations confirming that this layer is widespread (Taylor Fork video, Cooke City photo/ video, Lionhead video). Follow along for more information as conditions evolve.
Today, human-triggered avalanches breaking deeper than the thin layer of new snow are unlikely and the danger is rated LOW.
Upcoming Education Opportunities
The West Yellowstone Beacon Park is up and running! Stop by to check it out and practice with your rescue gear.
See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events and opportunities to check out:
BEGINNING TONIGHT! January 20 + Field Day. Our popular Avalanche Fundamentals with Field Course is perfect as a refresher or an introduction to avalanches. We are introducing a new format with four pre-recorded lectures to watch at your convenience, a live question and answer session, and a choice of a snowmobile or ski/ board-based field day occurring the following two weekends.
Every Saturday near Cooke City, 10 a.m.-3 p.m. FREE snowpack update and transceiver/rescue training. Stop by for 20 minutes or more at the Round Lake Warming Hut.
The Bozeman Daily Chronicle ran a story on a-day-in-the-life of an avalanche forecaster that highlighted Dave Zinn.