Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, March 31, at 7:30 a.m. Jeff King at Edward Jones, in cooperation with the Friends of the Avalanche Center, sponsors today's advisory. This advisory does not apply to operating ski areas.
The Bridger Range, northern Gallatin Range and mountains around Big Sky got 13-15 inches of creamy snow since yesterday morning. The southern Madison Range picked up another 5-6 inches with Cooke City getting 8 inches more. Winds have been blowing west to southwest and are currently reading 20-30 mph, a bit less than yesterday morning. Mountain temperatures are currently in the low to mid teens under cloudy skies. Today will remain cloudy as westerly winds lessen to 15-20 mph. Cooke City may get 2-3 inches tonight while other mountains should only see a trace to an inch by morning.
The Bridger, Gallatin and Madison Ranges, the Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:
Winter was just granted a stay of execution. Storm totals are 12-15 inches (1.2-1.7 inches of Snow Water Equivalency) from West Yellowstone to the Bridger Range. Cooke City has closer to 2 feet of dense powder (2.2 inches of SWE) which is where Mark and his partner are doing field work. The warm snow stuck to the steepest of faces giving the mountains down there a Himalayan feel. The winds also gusted to 60 mph loading many slopes, but even on sheltered aspects below treeline natural slides were breaking on the new snow one foot deep.
One to two inches of snow water was added to the snowpack quickly. In the Bridger Range this was added to three inches of water weight from last week. That's a lot of stress and the snowpack is more unstable because of it. Facets 2-3 feet under the surface are being heavily taxed, plus there's still snow at the ground level fracturing as a slide on Cedar Mountain on Friday demonstrated (photo). This winter, every time we have gotten a large load on our snowpack we've seen large avalanches. I have no reason to believe today will be any different.
Wind-loaded slopes near ridgelines or above treeline will be especially prone to avalanching. If the clouds lift I expect to see natural slides; most of these will be wind slabs of new snow. But with faceted layers in the snowpack, avalanches that initiate from wind drifts may step down to deeper layers. For today, the avalanche danger is rated HIGH on all wind-loaded slopes. Slopes not affected by the wind will have a CONSIDERABLE danger.
Mark will issue the next advisory tomorrow morning at 7:30 a.m. If you get out in the backcountry let us know what you find. You can reach us at 587-6984 or email us at mtavalanche@gmail.com