Good Morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Tuesday, April 3rd at 7:00 a.m. Today’s advisory is sponsored by the Yellowstone Club Community Foundation and Montana Alpine Guides. This advisory does not apply to operating ski areas.
Winter has Spring in a head-lock and won’t let go. Since 5 a.m. yesterday morning 4” fell in the Bridger Range, 8-10” around Big Sky and the southern Madison Range, 4” outside West Yellowstone and 6” outside Cooke City. Temperatures are in the single digits under partly cloudy skies and wind is west to northwest at 20-35 mph in the northern areas and 10-25 mph in the south. Today will remain partly cloudy with mountain temperatures reaching the high 20s. Wind will remain the same speed, but shift southwest. Tonight 1-2” of snow is expected.
The storm has ended and snowfall totals are 12” around Bozeman and 16” around Big Sky and Cooke City. The snow density was near 10% with a measured snow water equivalent of 1.2” to 1.6”. This new snow avalanched easily yesterday, on both wind-loaded and non-wind-loaded slopes as this short video shows. Wind yesterday and last night drifted snow into slabs at least 2’ thick that will be easy to trigger. Although the snowfall has stopped, slopes are still unstable. Fortunately, the older snow is strong and avalanches breaking deep are not expected. Alex was in Cooke City on Friday and Saturday and was able to trigger wind-slabs (video). This new wind-blown snow will react similarly around Bozeman, Big Sky and Cooke City today.
Yesterday, new snow and wind created widespread avalanches. Today requires careful snowpack evaluation since signs of instability are decreasing, such as cracking, collapsing, and natural avalanches. For today, the avalanche danger is rated CONSIDERABLE on all wind-loaded slopes since triggering slides is likely. On slopes without a wind-load, triggering slides is still possible and the danger is rated MODERATE.
The southern Madison and southern Gallatin Ranges recorded a storm total of 9” of snow (.8” SWE) with Lionhead getting 4”. Today’s avalanche concern is with this new snow, especially if it has been blown into wind slabs. Additionally, winds made cornices bigger and easier to trigger (photo). Be extra careful on wind-loaded slopes and be suspect of cornices breaking far back from their edge. In general, older snow is strong, and deeper avalanches are unlikely. For today, the avalanche danger is rated MODERATE on all slopes.
Wet Snow Avalanches
April sunshine, no matter how brief, will begin to melt the snow surface and create wet avalanches. I do not expect this to be widespread, but if you witness pinwheels rolling downhill I would anticipate wet loose avalanches will follow.
If you get out and have any avalanche or snowpack observations to share, drop a line via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).
Info and Announcements
Our last daily advisory will be this Sunday, April 8th. Afterward, we will issue weather and snowpack updates on Monday and Friday mornings for most of April.
Hyalite Canyon road is closed to vehicles and reopens May 16th.
Send us your observations on Instagram! #gnfacobs
Posting your snowpack and avalanche observations on Instagram (#gnfacobs) is a great way to share information with us and everyone else this spring.
