Human triggered avalanches remain possible today, especially in steep, rocky, wind exposed areas at the middle and upper elevations. Buried crust-facet combinations lurk on NE through E through S slopes, though their strength should improve after today's warm up and refreeze. Moniter the effects of the sun on the snow surface today and minimize exposure time on steep sunlit slopes.
Stubborn wind slabs that are 1-2 feet deep linger in the alpine. Easterly winds on Tuesday helped to form cohesive slabs of snow in unsual locations. Pay attention to signs of instability such as cracking within wind drifted snow.
Avalanches could occur on both the 3/29 and 3/20 interface, but will trend towards unlikely as crust development occurs. The 3/29 interface is 1-2 feet below the surface of the snow and the 3/20 interface is 2-3 feet below the surface of the snow. Both layers are buried within the top meter of the snowpack and are reacting in the medium to hard range in stabily tests, with a mix of propagating vs. non-propagating results.
Snowmobile triggered wind slab avalanche that failed on the 3/29 interface, as viewed from Pyramid. 20230405-SS-AMu-R2-D2-I East facing B-Z Bowl @ 9,200'.
Wet loose avalanches will continue to be a concern at the middle and lower elevations today as the spring warm up continues. Look for signs of instability such as roller balls on sunlit slopes.
Low elevations began showing signs of Wet Loose activity Tuesday afternoon.
Spring warm up continues today, with above freezing temperatures expected from the valley floor to the highest peaks. Clouds could gradually increase throughout the day as a moisture starved short-wave trough begins to impact the area tonight. These clouds could mitigate some wet loose development at the lower elevations but there is some uncertainty surrounding this situation. Wind slabs are prevalent in the alpine and their sensitivity to triggers could increase with solar input.
Recent avalanche activity was observed in Avalanche Canyon yesterday, mostly wind slabs that were size 1.5 or less.
Have left the 3/20 and 3/29 persistent slab problems in place for now, but sensitivity is expected to go down after the peak heating today and subsequent refreeze tonight. Clouds should mitigate some solar impacts tomorrow, and then we are back into full on high pressure with seasonal to above average temperatures. Looking at the long term forecast it's not looking very snowy for April right now, but that could obviously change.
