Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, March 18th, at 7:30 a.m. Cooke City Bearclaw Bakery and Super 8 in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
It snowed above 7,000 feet last night and rained below. At 6 a.m. the Big Sky area and Bridger Range picked up 5 to 6 inches of wet snow; Cooke City got 2-3 inches and 1-2 inches fell everywhere else. At 9,000 feet temperatures are in the upper 20’s with west winds blowing 15 mph and gusting to 25 mph. Precipitation will taper off this morning after dropping another inch or two, then skies will clear tonight with sunny and warm weather returning Thursday and Friday.
Bridger Range Northern Madison Range Cooke City
The Bridger Range, northern Madison Range and Cooke City picked up .7-.9 inches of snow water equivalency (SWE) in the last 36 hours. The freezing line bumped between 7,000 and 9,000 feet so snowfall amounts varied, but generally five to seven inches of wet, gloppy snow fell.
- One avalanche problem lies with the new storm snow. Yesterday skiers around Cooke City were able to get snow to move on steep slopes because it was not bonding well. It is still snowing and on steep terrain I expect you could trigger avalanches that may not break wide, but will travel far downhill, especially if the bed surface is an ice crust.
- A second avalanche issue is wet avalanches found on low elevation slopes where it rained. I expect you could trigger slides on anything steep (road cuts, creek embankments and other terrain traps).
For today the avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees and MODERATE on all others. Eric made a video of what the snowpack looked like after three days of non-freezing temperatures—wet and weak.
Southern Madison Range Gallatin Range Lionhead Area near West Yellowstone
Only 1-2 inches of snow (.1-.2 inches of SWE) fell in the other ranges. The new snow is not a concern, but the weak, wet, unsupportable snowpack is. Yesterday a few of us slogged into Bacon Rind. We stopped at a meadow near 9,000 feet to dig a snowpit and found our two previous snowpits fully visible (photo): one from January 27 and the other from two weeks ago! It has barely snowed in six weeks and everything looked frozen in time, but nothing was further than the truth. The snowpack was 100% different from our pit two weeks ago. Back then it had weak layers of surface hoar and was dry; now it’s a wet, unsupportable, isothermal snowpack with every grain of snow melted and reshaped. The freezing temperatures last night likely created a crust on some slopes, but it will not be very supportable. The ski down was horrible. I’ve never skied snow that was so bad for so long. Our fat skis would submarine to the dirt, which was the only solid surface we could initiate a turn on. On rollovers we could get the wet snow to break free and slush downhill. For today the avalanche danger is MODERATE on all slopes because the snowpack is wet and has lost a lot of its structural integrity.
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.