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RegisterApr 3rd, 2016–Apr 4th, 2016
Stevens Pass.
Winter will make a brief comeback on Monday! The avalanche hazard should increase in the afternoon as shallow storm slabs become more sensitive and with elevation as fresh wind slabs build on lee aspects.
Winter-like conditions will make a brief comeback on Monday as a front passes through early Monday morning and cool post-frontal showers follow in westerly flow.
A cooling trend during the day Monday should generally help new snow bond to older moist snow and surface crusts. Even with the cooling trend, subtle daytime warming will make shallow storm slabs possible by the afternoon. Also, heavier showers depositing graupel layers may locally make storm slabs more sensitive to human triggering.
Persistent westerly winds will transport new snow onto lee slopes near and above treeline Monday and Monday night. Firm wind transported snow and snowpack cracking can be good signs of wind slab layers. The wind slab problem will be elevated above treeline where more snow and stronger winds will build fresh wind slabs on lee aspects.
Loose wet avalanches will not be listed as a primary avalanche problem Monday. However, small loose wet avalanches involving new storm snow will be possible on any steeper solar slope during prolonged sunbreaks Monday.
The likelihood of cornice failure will lower Monday due to cooler weather. However, cornice releases can be unpredictable during the spring so continue to be aware of the overhead hazard and that cornices can break much further back than expected along ridges.
Although not listed as an avalanche problem, large, powerful glide avalanches can release unexpectedly so avoid areas below steep unsupported slopes or rock faces.
Weather and Snowpack
A large upper ridge has been over the Northwest for several days resulting in warm and dry weather. A spring avalanche cycle occurred in most areas over this stretch, likely peaking Thursday or Friday during the warmest temperatures and lightest winds. After a stormy March, the snowpack has undergone significant settlement over the last week.
Frequent March storms have built unusually large cornices along many ridges.
The mid and lower snowpack along the west slopes should generally be a stable mix of crusts and layers of moist and rounded snow crystals.
Recent Observations
Numerous professional and recreational observations focused on the spring avalanche cycle that occurred over the last several days throughout the west slopes of the Cascades.
On Saturday, a cornice failure and wet snow avalanches were observed above treeline on the Worms Flow route on Mt. St. Helens reported via the NWAC observation page.
The most recent observation comes from Dallas Glass in the Paradise area on Sunday. Dallas observed several small skier triggered loose wet avalanches mid-day on an east aspect above treeline at the 7200' level.