Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Thursday, April 7, at 7:30 a.m. The Pinhead Classic, in cooperation with the Friends of the Avalanche Center, sponsors today’s advisory. This advisory does not apply to operating ski areas.
Like Rocky in the last round of a title fight, old man Winter is off the ropes and punching wildly. At 6 a.m., 10-12 inches of new snow has fallen outside West Yellowstone and 7 inches outside Cooke City. All other weather stations are showing 4 inches with temperatures in the high teens and light west to southwest winds at 10 mph. Winds will pick up to 15-25 mph by tonight and snow will continue to fall into Friday. By morning I expect a foot of snow in the southern mountains and 6-8 inches everywhere else.
The Bridger, Gallatin and Madison Ranges:
The snowpack in the Bridger, Gallatin and Madison Ranges is strong. Our primary avalanche concern is new snow that’s been wind-loaded, the same concern we’ve had for many weeks. The snowpack has been getting loaded with fresh snow almost daily, but the amounts are incremental which does not put undue stress onto the pack. Yesterday, the ski patrols around Big Sky were only able to trigger small pockets of windblown snow. Mark and I toured the northern Gallatin Range and found stable conditions with no evidence of recent avalanche activity, even in the alpine. Last night’s 4 inches coupled with today’s snowfall will keep the possibility of triggering slopes very real today. This morning, given the recent snowfall and light winds, the avalanche danger is rated MODERATE on all wind-loaded slopes and LOW on all other terrain. If snowfall is heavy today I expect the danger will rise to CONSIDERABLE on wind-loaded terrain.
The Lionhead area near West Yellowstone, the mountains around Cooke City and the Washburn Range:
The mountains outside West Yellowstone and Cooke City have been hit with a lot of snow in a short period of time—a reliable recipe for avalanches. In the last three days over 2 inches of snow water equivalency has fallen. Although these mountains have almost 12 feet of strong snow on the ground, I expect to see avalanches breaking directly under this new snow. Slopes that were wind-loaded will be especially sensitive to triggering, but with all this new snow I suspect you could trigger slides on other slopes too. On Tuesday, a natural avalanche outside Cooke City on Scotch Bonnet provided conclusive evidence that instability exists. For today, the avalanche danger is rated CONSIDERABLE on all wind loaded terrain and MODERATE on all others; however, if the forecast is correct and it continues to snow hard, I expect the avalanche danger to rise to CONSIDERABLE on all slopes. A considerable danger means natural avalanches are possible and human triggered slides are likely.
Mark 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.
Last Advisory
The last avalanche advisory of the winter is scheduled for this Sunday, April 10th. A government shutdown may pre-empt that, but we won’t know until midnight Friday.