Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, March 14th at 6:45 a.m. Today’s advisory is sponsored by Buck Products and Wisetail. This advisory does not apply to operating ski areas.
Cooke City received an inch of snow overnight. At 6 a.m. it is drizzling in the valleys since the freezing line is at 9,000 feet. Winds are west to southwest at 15-20 mph with gusts in the thirties. Today will be cloudy with scattered rain this morning, and snow at the higher elevations. Accumulations will only amount to an inch of snow or .1” of precipitation. Mountain temperatures will rise to near 40F today and likely not freeze tonight under mostly cloudy skies.
RAIN
With rain comes avalanches. A drizzle will not affect the stability, but a hard rain would quickly weaken the snow and trigger avalanches. Heavy rain is not forecasted, but forecasts can be wrong. Rain is the starting pistol to get out of avalanche terrain; think, “Run, Forrest, run!” And really, who wants to be out in the rain anyway.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone Cooke City
There are two independent avalanche concerns today, rain and cornices. The first is easy: rain means you should pack up and go home because rain can trigger wet avalanches. The second are cornices which have grown larger than we’ve seen in years. Above freezing temperatures make them weak and easy to break. At the ridge they can be triggered without any effort by a passing skier or snowmobiler. Many people have been injured or killed when a cornice tumbled downhill with them on it. Cornice chunks also trigger avalanches which recently occurred outside Cooke City, at Lionhead (video), and near Big Sky (Fan Mtn). Skiers had a close call with a cornice up Hyalite and monster overhangs of snow in the Bridger Range are ripe to break.
Strong west to southwest winds loaded slopes in the last week that could be triggered, either by cornices or by a skier or snowmobiler. These wind slabs are a few feet thick around Cooke City and Lionhead, and a few inches thick elsewhere. Alex and his partner skied Saddle Peak in the Bridger Range on Sunday and steered clear of wind-loaded terrain since it was still possible to trigger an avalanche. His snowpit revealed good stability on all other slopes.
For today, the avalanche danger is rated MODERATE on all wind-loaded terrain and LOW on all others. If it rains, the danger will spike rapidly to Considerable or High.
Check out our Photo page for many recent pictures of cornice triggered avalanches and slides in wind-loaded terrain.
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.