Good Morning. This is Alex Marienthal with the Gallatin National Forest Avalanche Advisory issued on Monday, March 27th at 6:50 a.m. Today’s advisory is sponsored by World Boards and Montana State Parks. This advisory does not apply to operating ski areas.
At 4 a.m. the mountains have 2” of new snow in the southern ranges and 1” in the north. Snotel has not reported data since midnight and snow amounts could be slightly higher in the southern ranges. Temperatures this morning are 20s F and wind overnight was southwest at 10-20 mph with gusts of 30-40 mph. Temperatures today will be high 20s to 30s F with wind at 5-15 mph out of the southwest today and north to northwest tonight. Mostly cloudy skies and light snow showers today precede increased snowfall this evening. The mountains could get 3-6” near Bozeman and Big Sky with 1-2” elsewhere.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
A couple inches of snow overnight with light to moderate wind contributes little to the avalanche hazard today. Freezing overnight and cool daytime temperatures for multiple days have preserved a thick crust below last night’s snow, which creates a generally stable snowpack. Over the weekend, skiers found recent snow bonded well to the old snow surface, which Eric also found in Beehive (video). Fresh wind slabs that formed overnight near ridgelines are small, but can carry a skier or rider and have high consequences over cliffs and steep terrain. Loose snow avalanches are possible to trigger today and can run far on the firm crust below recent snow (photo, photo). Be cautious in or below steep, rocky terrain that could produce natural dry or wet loose avalanches as temperatures warm or if sun shines.
Avalanches deeper than a few inches are unlikely, but not ruled out on shady, high elevation slopes where deeper dry snow exists. On Friday, riders in the Crazy Mountains saw a recent large 3-6 foot deep avalanche on a heavily wind loaded, high north facing slope. Although outside our advisory area, this slide and a couple observed last week in Cooke City (photo) and the Bridger Range (photo) are examples of isolated deeper dry snow instabilities that could be encountered. Wet avalanches deeper than a few inches are unlikely today with forecast cool temperatures and cloud cover.
Today, the avalanche danger is LOW and could increase this afternoon for loose wet snow avalanches if the sun shines more than expected. Be diligent with snowpack assessment and anticipate rapid changes during variable spring weather. Continue to enforce safe group travel habits and clear communication.
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.
Doug 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.