Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Forecast issued on Friday, April 5th at 6:45 a.m. Today's forecast is sponsored by Yellowstone Ski Tours and Map Brewing. This forecast does not apply to operating ski areas.
Since yesterday morning the mountains around West Yellowstone and Cooke City picked up a few inches of snow at upper elevations and rain down low. The rest of the forecast area saw a trace of snow above 8,000 ft. and light rain at lower elevations. This morning, temps range from the upper 20s to low 30s F under partly to mostly cloudy skies. Winds are blowing 5-20 mph out of the west-southwest. Today, temps warm into the 40s and winds remain light to moderate out of the west-southwest. Increasing precipitation this afternoon will deliver light rain below 8,000 ft. and 1-2” of snow up high. Warm and wet conditions continue through tomorrow.
Yesterday, temperatures in the 40’s did not produce widespread wet snow avalanches. A few small wet loose slides were observed north of Bridger Bowl, but in general avalanche activity was minimal. At this point, the snowpack has been through multiple freeze-thaw cycles which has conditioned the snowpack to free moving water. All but high north facing slopes have well developed drainage channels which helps reduce wet snow avalanches as temps climb above freezing.
Overnight, most areas saw a very light refreeze or no freeze at all. Today, the upper layers of the snowpack will soften quickly as temperatures warm. In addition to above freezing temps, light rain is forecasted to arrive by early afternoon. Rain on snow not only makes miserable riding conditions but it quickly destabilizes the snowpack (photo). Today, above freezing temps and the likelihood of rain makes the movies or house projects a good alternative to the backcountry. If you do head out, assess snow conditions carefully and avoid steep terrain if you observe wet roller balls or sink into soft slushy snow above your boots.
Although wet snow avalanches are the main concern, a skier or rider could still trigger an isolated wind slab on upper elevation slopes facing north through east (photo). Cornices are also a growing concern. These massive overhanging chunks of snow are losing strength quickly as temperatures warm (photo). Be extra cautious when traveling on slopes below cornices and give them a wide berth along the ridgelines.
Today, wet and dry snow avalanches are possible and the avalanche danger is rated MODERATE.
The Hyalite road is closed to motorized travel until May 16th. Bike and foot traffic is allowed.