Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 16th, at 7:30 a.m. Cooke City Motorsports and Yamaha in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
This morning mountain temperatures are in the upper 30s to mid-40s F and winds are blowing 15-30 mph out of the W-SW with stronger gusts being recorded in many mountain locations. Great Falls weather station at Big Sky recorded gusts up to 87 mph overnight. Today, Skies will be partly to mostly cloudy and mountain temps will stay in the 40s F. Winds will continue to blow 15-30 mph out W-SW this morning, but will gradually decrease throughout the day. A weak weather disturbance will move over the area tonight and tomorrow producing valley rain and mountain snow. 1-3 inches of snow is possible above 7,000 ft. by tomorrow afternoon.
Bridger Range Madison Range Gallatin Range
Lionhead Area near West Yellowstone Cooke City
It's official - the snowpack is coming unglued. It has been nearly 72 hours without a freeze and the snow is quickly losing cohesion and strength. Yesterday, skiers near Cooke City observed wet loose avalanches on steep, north facing slopes and the Bridger Bowl Ski Patrol kept the Ridge closed all day due to a weakening snowpack.
Today, conditions will continue to deteriorate as free moving water permeates through the snowpack. Wet loose avalanches are the main concern - these will be likely with human triggers on all steep slopes today. Natural wet loose avalanches will also be possible in steep terrain. The snowpack structure is not ideal for wet slab avalanches, but due to the rapid warm-up they can't be ruled out entirely. Steep, rocky terrain where faceted snow might exist will be areas most susceptible to wet slab avalanches.
Another avalanche problem is cornices. Yesterday, a skier north of Cooke City observed natural cornice failures. These overhanging monsters will gradually succumb to gravity as they continue to lose strength. Today, it will be a good idea to avoid slopes below large cornices and them a wide berth along the ridgelines, as they have a tendency to break farther back than one might expect.
Today, a weakening snowpack will make human triggered avalanches likely on slopes steeper than 35 degrees which have a CONSIDERABLE avalanche danger. Less steep slopes have a MODERATE avalanche danger.
Doug will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.