Snowpack Summary for 3/17/2017
Sponsored byUpdated: Friday, March 17, 2017 8:35 PM · Issued: Friday, March 17, 2017 8:00 PM
Observer: Gabe Coler
Bottom LineExpect a continuation of the recent weather with a mix of snow and rain. When temperatures are well above freezing (especially overnight) or there is significant rain, then the avalanche danger will be higher with our chief problem being Loose Wet avalanches. Similarly if we are lucky enough to get some clearer weather or Sunday, slopes that are in the sun could be melting enough to produce Loose Wet avalanches. When things are below freezing and we're picking up a bit of snow, we may see some shallow wind slab development. With such warm temperatures, rain, and then a little new snow and wind, Cornices are more unpredictable than ever.
Recent ActivityThe last few days have been typified by warmer stormy weather. We've had our most avalanche activity during the days when temperatures have been well above freezing and often rainy. This has resulted in Loose Wet Avalanches and Cornice Failures. Thursday was the exception with a few inches of snow and winds resulting in shallow Wind slabs like Aaron saw on Tumalo as well as cornice growth.
Snowpack DiscussionThe upper snow pack has been effected by the warm temperatures and rain which means it's a mix of melt forms and melt-freeze crusts. Below that the snow is rounding. Observers haven't been finding any significant buried weak layers in the snow pack, which means that all avalanche activity is directly related to the immediate weather at hand. If it's warm or raining and the surface snow is melting more than a few inches deep, there is probably a chance for Loose wet avalanches. If we pick up a few inches of new snow look for signs of shallow Wind Slabs like blown-in snow, variations in new snow depth, and cracking on lee aspects. I expect any Wind Slab problem to be shallow.
DISCLAIMER: This snowpack summary describes general backcountry conditions and local variations always occur.