These small crowns indicate that new snow may not bond well to the old snow surface. Photo: B. Fredlund
19-20
GNFAC Avalanche Forecast for Thu Nov 28, 2019
Snowpack and Avalanche Discussion
<p>As we feast on turkey today and leftovers tomorrow, Ms. Winter will be hard at work carpeting the mountains with snow. Not to be unthankful on a day of thanks, but it’s about time! The snowpack around Bozeman, Big Sky and Cooke City is mostly strong and stable. Dave and I spent the last 2 days in Cooke City and found good stability in the 2-3 feet of snow (<strong><a href="https://youtu.be/6O2DFTnHPcw">video 1</a></strong>, <strong><a href="https://youtu.be/ngLsPMwRmfQ">video 2</a></strong>, <strong><a href="https://www.mtavalanche.com/images/19/stable-snow-cooke-city">photo</a>…;). This dovetailed with observations from skiers in Hyalite, Bridger Range and around Big Sky.</p>
<p>Avalanche concerns through Saturday will be limited to the new snow. In some areas it is falling onto a crust and may not adhere well. Other areas may have weak surface snow which could slide. Additionally, wind will drift snow into dense slabs which could be easy to trigger. Avalanche activity, no matter how small, is a sign of instability, as are cracks shooting out from your skis or sled. Avoid slopes with similar aspect and elevation if you see these signs.</p>
<p>The snowpack south of Big Sky to West Yellowstone is shallow and weak. Alex and Dave walked and skied into Lionhead a week ago and found 6-18” of snow on the ground, all of it faceted. Faceted snow is unsupportable, feels like sugar in your hand and is very weak, which Alex shows in his <strong><a href="https://youtu.be/i6DWvLU0Eks">video</a></strong>. In Carrot Basin 7” of snow has fallen (.6” SWE) and I expect the rest of these ranges to catch up to these amounts soon. The snowpack will not be able to support the weight of much new snow. <em>The avalanche danger is rising and we are prepared for a possible Avalanche Warning if the weather forecast holds true.</em> A foot or more of snow (1” SWE) would make for very dangerous and widespread avalanche conditions. Traveling in the backcountry during the storm is not recommended. We discuss this situation in <strong><a href="https://youtu.be/VOudepXmDeY">Episode 2</a></strong> of our Dashboard Talks.</p>
We are working hard to get out in the field to collect information about the snowpack and we want you to help us by submitting an observation form. Your observations are critical to us developing a complete picture of what is happening in the mountains. You can also email us (mtavalanche@gmail.com), leave a message on our phone (406-587-6984) or Instagram (#gnfacobs).
Forecast link: GNFAC Avalanche Forecast for Fri Nov 29, 2019
This snowpit was on a NE aspect at 10,000' on Henderson Bench. It was 3 feet deep and stable. Facets (weaker snow) are getting stronger. We will keep an eye on these to make sure the positive trend continues. Our snowpit profile is here. Photo: GNFAC
Forecast link: GNFAC Avalanche Forecast for Thu Nov 28, 2019