This avalanche information bulletin is issued on April 7, 2014 and does not expire. The Gallatin National Forest Avalanche Center has stopped issuing avalanche advisories for the season. Traveling in the backcountry requires carefully snowpack evaluation on the slopes you intend to ride or ski. Avalanches don’t end until the snow melts.
Some avalanche concerns to keep in mind:
1. NEW SNOW AND WIND-LOADING
The greatest avalanche concern is new snowfall and wind-loading. The likelihood of triggering avalanches spikes during and immediately after significant snow storms. Wind loaded slopes, usually found near ridgelines, are especially dangerous. Any instability associated with the new and/or windblown snow can easily be found in the upper few feet of the snowpack. Instabilities associated with new snowfall are typically around for only a few days.
2. WET SNOW AVALANCHES
Spring is synonymous with wet avalanches. With the sun higher in the sky and daytime air temperatures above freezing, wet avalanche activity increases. More importantly, above freezing temperatures at night add to the danger and can create unstable conditions. South-facing slopes get the brunt of incoming solar radiation, but warming eventually reaches all aspects as spring progresses. Be aware that sunny aspects may have a wet snow danger while shadier slopes still have a dry snow avalanche danger. Pinwheels and large rollers of snow are signs of increasing avalanche danger. Punching to the ground in wet, unsupportable snow is another bad sign. Wet avalanches, whether loose snow or slab, can be destructive and powerful.
3. CORNICES
Cornices are massive this season. They can break off suddenly and pull back onto the ridge top and catch people by surprise, even on flat ground above the slope. A cornice fall can entrain loose surface snow or trigger deep slab avalanches. Regardless of whether a cornice triggers a larger slide or not, a falling cornice is dangerous to anyone in its path.
4. DISCLAIMER
Yes, there’s always a disclaimer. If snowfall continues there’s a real possibility that new weak layers will be buried, creating lingering, possibly widespread instabilities. Always assess with diligence the slope you’re about to play on. Do not let your guard down. Always travel with a partner, carry rescue gear and only expose one person at a time to avalanche terrain. We live by these rules in winter and spring.
Have a safe and enjoyable spring and summer!
Doug, Mark and Eric