Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Sunday, March 26th at 7:00 a.m. Today’s advisory is sponsored by Buck Products and Gallatin County Search and Rescue. This advisory does not apply to operating ski areas.
Since yesterday morning the southern mountains got 1-2” of new snow and the northern mountains did not get any. Temperatures this morning are teens to low 20s F. Wind is 5-10 mph out of the west to southwest and northwest near Cooke City. Today, under partly sunny skies temperatures will be high 20s to low 30s F with west to southwest wind at 5-10 mph. Light snow tonight could produce 1-2” near Big Sky and in the southern ranges with a trace to 1” near Bozeman.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
Freezing overnight temperatures and cool days have maintained a thick, supportable crust at the surface of the snowpack on all except for shady high elevation slopes. The snowpack is generally stable and avalanche concerns are confined to a few inches of recent snow. Eric was in Beehive yesterday and found firm crusts on sunny slopes, and dry snow on shady slopes that was bonded well to the old snow surface (video). Skiers in the northern Bridger Range yesterday observed natural dry loose avalanches that initiated at rock outcrops and ran long distances (photo, photo). Similar dry or wet loose avalanches are possible to trigger today or could run naturally in steep rocky terrain. Be aware of terrain overhead that could produce large loose snow avalanches during increasing temperatures or intermittent sunshine.
The sun is more powerful each day as it gets higher in the sky and the briefest bout of sunshine will make the snow surface moist and wet loose avalanches easier to trigger. Move to shadier slopes if you encounter signs of increasing wet avalanche hazard such as a moist snow surface, roller balls, or sink into wet snow deeper than your boot. Deeper wet slides, similar to a few in Beehive last week (photo, photo), will be possible when the surface crust melts (video). Today, relatively cool temperatures and cloud cover will minimize wet snow avalanche hazard and wet avalanches deeper than a few inches are unlikely.
Dry slab avalanches are unlikely, but may be encountered on shady slopes that do not have a firm refrozen crust below recent snow (photo). Practice safe travel techniques, be diligent with snowpack assessment, and anticipate rapid changes during variable spring weather.
The avalanche danger today is LOW and will rise to MODERATE for wet snow avalanches this afternoon.
CORNICE DANGER
Cornices are extra big this year (photo) and warm temperatures weaken their grip on the ridgelines. They can break far from the edge and can trigger large avalanches on slopes below.
I will issue the next advisory tomorrow morning by 7:30 a.m.
We rely on your field observations. Send us an email with simple weather and snowpack information along the lines of what you might share with your friends: How much new snow? Was the skiing/riding any good? Did you see any avalanches or signs of instability? Was snow blowing at the ridgelines? If you have snowpit or test data we'll take that too, but this core info is super helpful! Email us at mtavalanche@gmail.com or leave a message at 406-587-6984.