Warming temperatures combine with snow, wind, mixed precipitation, and rain to paint a complex avalanche picture. It could become very dangerous out there. Keep it simple and avoid all avalanche terrain if snow changes to rain, sleet, or freezing rain in your area.
As the storm ramps up, wind slabs will be just another problem to manage. Keep it simple and avoid slopes steeper than 35 degrees where you suspect more than 6" of snow has piled on.
Anticipate where wind slabs are living by looking for where the snow is blowing. Corncies are often great indicators of potentially wind loaded terrain beneath.
Photo: Joe Dellaporta
We're expecting 6-10" of snow before precipitation changes to rain at upper elevations sometime on Friday. Rain on the fresh snow will rapidly destabilize it and creates conditions for wet loose avalanches. . Rain could also saturate colder snow prior to the current storm, resulting in large avalanches. With enough water entering the snowpack, we could see large natural avalanches become likely or human-triggered avalanches becoming very likely. Warming may also occur more significantly at at higher elevations with cold air trapped at lower levels. In this case, freezing rain or sleet mean that rain falls on the slopes that could be not far above you and you risk some exposure to slopes above. Don't wait for the rollerballs. Keep it simple and execute a safe exit route plan as the snow transitions and avoid exposure to open slopes steeper than 35 degrees.
(3/24/2022)
Wet loose avalanches initiating in previously wind loaded terrain. Table Mountain, northwest aspect at ~5000'.
Photo: NWAC Public Obs
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We're putting around 1" of water equivalent on a cold, layered snowpack at lower elevations. The weight may test these layers to increase the likelihood of reaching the tipping point either of two layers of buried surface hoar. You might find the first about 1 ft down (buried 12/18). We have limited information about this interface as it does not appear to be widespread, but we think it may have been preserved in some wind-sheltered areas on N and NE aspects. It shows up in a very pronounced grey stripe in a test pit near Mitchell Creek on 12/20. The older 12/8 buried surface hoar also showed up clearly in the aforementioned test pit from Mitchell creek, reminds us that this widespread layer remains in the upper 2' of the snowpack. This layer has the potential to produce isolated avalanches up to size 2.5. Avalanches triggered on the 12/18 weak interface could step down to this layer to produce avalanches that could ruin your day.
Given the complex and layered nature of the current snowpack, keep your terrain choices simple and avoid larger open slopes steeper than 30 degrees.
(12/20/2022)
12/8 PWL and new layer of buried surface hoar 12/18.
Public Field Report: Mitchell Creek, Mt Hood Meadows
Photo: Dave Watson
Warming trends frequently produce challenging avalanche conditions and this is no exception. Expect avalanche conditions to worsen as the day progresses. Plan safe exit routes. Stick to conservative terrain choices and avoid avalanche terrain altogether if snow transitions to rain or ice.
Share an observation with us if you make it out. Even a fuzzy in picture in the storm is better than nothing.
