Avalanche forecast for Wednesday, January 22nd.This forecast does not apply to operating ski areas.. This forecast will be posted to social media accounts and recorded on the phone hotline at 406-587-6981.
A large ridge of high pressure parked over the Pacific continues to bring strong winds, cold air, and some snow from Canada into the forecast area. Yesterday strong winds gusting 50-60 mph blew generally from the west (some WSW and some WNW).
This morning at 6 a.m. it's snowing with 6 inches near the Ridge at Bridger Bowl, 2-3 inches near Cooke City, and a trace to 1 inch in most other places. Winds eased since yesterday and are blowing from the NW 10-15 mph gusting to 30 mph. Temperatures are in the single digits F.
Today mostly during the morning hours another few inches should fall in the mountains near Bozeman, Big Sky and maybe Cooke City. Snowfall should end mid-morning but clouds will linger over most areas. Winds from the NW should ease by afternoon but continue bringing cold air. High temperatures will only rise a little bit reaching 10 deg or the low teens F at the most.
Wind slab avalanches will be the most likely problem today after yesterday's strong winds as well as strong winds from late last week. You'll surely find them under upper elevation ridgelines and cornices, but look for them at lower elevations where winds cross load gullies, subridges, and other terrain features. Yesterday in Sheep Creek near Cooke City, guides spotted a 200 ft wide wind slab that had released naturally. It may be harder to identify these areas with a few inches of new snow camouflaging the fresh wind slabs.
This wind loading will bump up the possibility of triggering a much larger persistent slab avalanche breaking on old weak layers of facets about 1-2 feet above the ground. These larger avalanches have become much less frequent with three spotted just over a week ago, and snowmobiler triggering deep shooting cracks on Sunday in the southern Madison Range.
Today in the southern Madison and Gallatin Ranges, in the Lionhead area near West Yellowstone, and in the mountains near Cooke City; the avalanche danger is MODERATE.
Wind slab avalanches are the main problem as well in the mountains near Bozeman, Big Sky and Island Park. Dave describes this problem well in his video from yesterday in Hyalite Canyon posted to YouTube. Fresh snow today will make it harder to identify these fresh wind slabs, but use your best judgement to estimate where winds deposited snow yesterday and avoid those slopes.
Persistent slab avalanches are unlikely, and old weak layers have gained strength on most slopes where the snowpack is over about 5 feet deep. Today in the Bridger Range, in the northern Gallatin and Madison Ranges, and the Island Park area, the avalanche danger is MODERATE on wind loaded slopes which are more widespread than not. Slopes sheltered from the wind without any recent wind loading have a LOW danger.
Thank you for sharing observations. Please let us know about avalanches, weather or signs of instability via the form on our website, or you can email us at mtavalanche@gmail.com, or call the office phone at 406-587-6984.