Good morning. This is Eric Knoff with the Gallatin National Forest Avalanche Advisory issued on Monday, March 23, at 7:30 a.m. Gallatin County Search and Rescue in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
At 4 a.m. skies are partly cloudy and mountain temperatures range from the upper 20s to mid-30s F. Winds are blowing 15-25 mph out of the W-SW. Today, an approaching storm will produce mostly cloudy skies by late morning with an increased chance or valley rain and mountain snow this afternoon. There is a chance for an isolated thunderstorm associated with the frontal passage, which should arrive by mid to late afternoon. Winds will increase out of the west as the storm approaches producing gusts over 30 mph. Temperatures will warm into the upper 30s to low 40s F, but will drop sharply once the front passes. By tomorrow morning the mountains will likely receive 2-4 inches of new snow. A more potent storm system is forecasted to impact the area tomorrow into Wednesday.
Bridger Range Madison Range Gallatin Range
Lionhead Area near West Yellowstone Cooke City
Yesterday, warm temps and abundant sunshine softened the snow surface on all aspects but due north. This morning, the snow surface will be frozen and locked up, eliminating the potential for wet snow avalanches. Upper elevation, north facing slopes will still hold some dry snow, which should be well bonded to hard underlying bed surface (video).
Today, increasing clouds, strong winds and cooler temperatures will help keep the wet snow danger at bay. There is the possibility that some low elevation slopes that didn’t receive a hard freeze could still produce some wet snow dribblers, but this is unlikely to produce a significant hazard.
The biggest concern today will be changing weather conditions. If today’s storm arrives with more energy than forecasted, multiple inches of snow could fall in a short period of time. This could produce small but widespread wind slabs in upper elevation, wind loaded terrain. Another concern is rain on snow. This storm could produce rain showers up to 7,000 feet. Fortunately, the lower elevation snowpack (what’s left of it) is well conditioned to free moving water and shouldn’t have much trouble dealing with a little rain. If rain starts to fall about 7,000 ft. it will be worth avoiding steep slopes in these areas.
Today, generally safe avalanche conditions exist and the avalanche danger is rated LOW. If the today’s storm arrives stronger and earlier than expected, the avalanche danger could rise to MODERATE.
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.