Archived Advisories

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Snowpack and Avalanche Discussion	Attached images	Attached Videos
Apr 8, 2013 - Doug Chabot Some avalanche concerns to keep in mind:1. NEW SNOW AND WIND-LOADINGThe 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...
Apr 7, 2013 - Doug Chabot Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityIn the last 48 hours close to an inch of Snow Water Equivalency fell in the Gallatin and southern Madison Ranges and mountains outside Cooke City (about 8-10 inches). The Bridger Range and Big Sky area got half that. A 2-3” frozen ice crust under this new snow can easily support...
Apr 6, 2013 - Doug Chabot Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityYesterday it rained in the valleys and snowed above 8-9,000 feet. The snowfall measured up to15% density and stuck well to the old snow surface, which was beginning to re-freeze. This is very good news because cold temperatures will continue to penetrate and cement the snowpack creating...
Apr 5, 2013 - Doug Chabot Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityMore wet avalanches occurred yesterday with mountain temperatures reaching 50F. Last night was the fourth evening without a freeze. Warm temperatures are infiltrating the snowpack, melting bonds and turning things soggy. Yesterday, a sizeable wet avalanche came down in closed terrain at the...
Apr 4, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityFor the last three days the snowpack has become warmer and wetter each day. Warm skies at night, which prevent radiational cooling, and low temperatures that barely reach 32 F have not been able to refreeze the snowpack enough to stabilize it. Wet avalanches occurred everyday this week at and...
Apr 3, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityMore wet loose and wet slab avalanches occurred yesterday at Big Sky (photo1, photo2) and nearby in Beehive Basin (photo). Watch this video from mid-March to see how quickly wet avalanches can slide and gain volume. Ski patrols at Bridger and Moonlight did not have similar activity but...		North Dakota ECT - March 31, 2013
Apr 2, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityYesterday the Big Sky Ski Patrol reported several large wet loose and wet slab avalanches. Strong sunshine and a lack of cooling winds allowed the snowpack to heat up and become unstable as liquid water percolated through it. Other wet slabs and wet loose avalanches were observed in the...
Apr 1, 2013 - Eric Knoff Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke City Clear skies and below freezing temperatures last night will keep the snowpack locked up and frozen this morning. With the snowpack resembling well cured concrete, there will be minimal avalanche hazard. The one exception will be high, north facing slopes where dry powdery snow can still be found....
Mar 31, 2013 - Eric Knoff Northern Madison Range Northern Gallatin Range Cooke City Yesterday, my partner and I toured into Beehive Basin expecting to find 1-3 inches of new snow. This was accurate up to about 9,000 ft., but above that elevation snow totals were around 4-6 inches. Skiers in Hyalite and the Cooke City area found similar conditions. This amount of snow combined with moderate west to northwest winds formed sensitive...
Mar 30, 2013 - Eric Knoff Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityAbove 8,000 ft. 1-3 inches of snow fell in most locations, below 8000 ft. precipitation fell in the form of rain. Depending on what the weather does today, there will be a few avalanche problems to consider.On lower elevation slopes, wet loose avalanches will be the main problem. Multiple...
Mar 29, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityIdeally during this time of year, the snowpack will experience a solid refreeze every night. In coming weeks, watch for nights when temperatures remain above freezing especially if they do so for multiple nights in a row. The NRCS SNOTEL sites are good sources for such temperature data. Also...
Mar 28, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityThere are two concerns today: wet loose snow avalanches (video) and falling cornices. Fortunately the snow surface refroze well last night and should act predictably today. The snowpack often provides clues that the wet snow avalanche danger is rising. Watch for growing pin wheels rolling...		A crown, some creep and ice.
Mar 27, 2013 - Doug Chabot Wet Snow Avalanche DangerYesterday, temperatures were not warm enough to create many wet avalanches. This will change today. Sunny skies with temperatures reaching the 40s will quickly wet the snow surface. Liquid water breaks bonds in the snowpack and weakens it quickly. Neither wind nor clouds will impede this process. Signs of increasing avalanche danger include sinking past your boot tops in moist snow and...		A crown, some creep and ice.
Mar 26, 2013 - Doug Chabot Wet Snow Avalanche DangerA bit of sunshine and temperatures rising well above freezing will create loose, wet snow avalanches today. Point release slides from cliffs, rock out-croppings or steep, sunny slopes, have the potential to knock a skier down and drag them into terrain traps. Pinwheels of snow, growing as they roll downhill, is a sign that surface snow is wet enough to slide. The wet snow avalanche danger will rise to...		By the time this is a problem, I'll be in the desert
Mar 25, 2013 - Eric Knoff Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CitySome avalanches are predictable and easy to understand, others are not. Yesterday we observed an avalanche north of Ross Peak in the Bridger Range that was a bit of head scratcher. The slide appears to be a natural that propagated hundreds of feet wide and failed on a non-wind loaded slope (...		By the time this is a problem, I'll be in the desert
Mar 24, 2013 - Eric Knoff Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityThe combination of sun, snow and good stability is making for great skiing and riding conditions. Yesterday, my partner and I toured into Frazier Basin the in the northern Bridger Range and observed tracks in steep avalanche terrain (photo). When conditions are stable, there is nothing wrong...
Mar 23, 2013 - Eric Knoff Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityYesterday, Mark rode in the Lionhead area near West Yellowstone and found generally stable conditions. He found recently formed wind drifts to be well bonded to the underlying snow surface. This is consistent with the conditions I found in McAtee Basin on Thursday. ...		Two Avalanche Problems To Consider
Mar 22, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityThe primary avalanche concern today will be wind slabs that formed yesterday from strong W winds. Ski patrollers at Bridger, Big Sky and Moonlight triggered many fresh wind slabs yesterday with explosives and ski cuts. Skiers on Saddle Peak triggered a wind slab near the summit 8-10 inches...		Two Avalanche Problems To Consider
Mar 21, 2013 - Mark Staples Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityNew snow + wind will make fresh wind slabs the primary avalanche problem today. Human triggered avalanches will be likely on steep, wind loaded slopes. On slopes without wind deposited snow, the main avalanche concerns will be layers within snow that has fallen since Saturday. Yesterday in...
Mar 20, 2013 - Doug Chabot Bridger Range Madison Range Gallatin Range Lionhead area near West Yellowstone Cooke CityFrom Saturday night to yesterday morning the mountains have gotten 6-12 inches of snow with strong winds. This snow fell onto a supportable melt-freeze ice crust on most aspects. Ice is a funny thing because we associate it with being slippery, yet that is not how it usually behaves once it’s...