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RegisterApr 6th, 2017–Apr 7th, 2017
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Very dangerous avalanche conditions will develop in the Mt. Baker area Friday and travel in avalanche terrain is not recommended. There's a lot of new snow above 5500 feet with more on the way, increasing the chances for very large avalanches above treeline and large wet snow avalanches below treeline.
Warm frontal moisture will spread northward and move over the Cascades late Thursday night through early Friday morning with snow levels 5500-6500 ft and increasing E-SE winds affecting the Cascade Passes and higher terrain of the southwest Cascades. After a brief lull in the precipitation Friday morning, showers should begin mid-day and increase in the afternoon, becoming particularly heavy in the Mt. Baker area. S-SW winds will increase and should become strong and gusty by mid-day with snow levels falling to 4000-5000 ft in the afternoon.
Very dangerous avalanche conditions will develop in the Mt. Baker area Friday and travel in avalanche terrain is not recommended. There's a lot of new snow above 5500 feet with more on the way (3.3 inches water equivalent in the last 48 hours!), increasing the chances for very large avalanches above treeline and large wet snow avalanches below treeline.
New wind and storm slab problems will initially be found above treeline, however these problems will creep into the near tree-line elevation band by the end of the day in the northwest Cascades. Southerly winds should primarily load W-N-E aspects, but very strong winds will cross-load slopes and create unusual loading patterns. Deep wind slab should exist above treeline. Unstable storm slabs should develop in wind sheltered areas during periods of intense snowfall accumulation. A mix of wind and storm slab and loose wet concerns should be seen near treeline.
Rainfall at lower elevations should activate loose wet avalanches on steeper slopes. Watch for wet surface snow deeper than a few inches, pinwheels and initial natural releases that indicate an increasing loose wet avalanche danger. Be wary of steep slopes with terrain traps such as cliffs or if heavily treed, where even a small loose wet avalanche could have big consequences.
Other avalanche problems not listed in the problem set:
Potentially large and destructive wet slab avalanches are possible in specific areas in the Mt Baker area near and below treeline on Friday where recent rainfall has regionally been the heaviest. Glide avalanches may also be possible in this area.
Recent cornices are very large and have likely been weakened during this most recent storm cycle. Natural cornice releases and resulting slab avalanches are dangerous and unpredictable. Give cornices a wide berth if traveling along ridge-lines and avoid slopes below large cornices. See a blog post regarding cornices here.
Weather and Snowpack
March was a wet and wild month for weather and avalanches in the Cascades. The last widespread avalanche cycle during this stretch occurred March 28th-29th.
Fair but cool weather was seen in the Cascades Monday and Tuesday. Reports generally indicated strong surface or near surface crust layers and shallow recent snow.
A stalled frontal boundary on Wednesday through the first half of Thursday brought heavy rain and snow to the Mt. Baker area with much lighter precipitation for the central-west and southwest Cascades. Snow levels were generally between 4500-5000 feet in the northwest Cascades and 5000-6000 feet in the central-west and southwest Cascades.
Recent Observations
North
NWAC pro-observer Lee Lazzara was at Little Devil Peak in North Cascades on Monday 4/3. Near and above treeline Lee found about 4 inches of recent storm snow over the most recent crust, and wind slabs averaging about 1 foot on N-E aspects below ridges. Snowpack tests indicated triggering of wind slabs to be stubborn. There was evidence of recent large cornice failures. The recent strong rain crust dominated the snowpack below treeline with shallow wet snow conditions during the afternoon. Shallow cold snow was preserved on steep shaded terrain near and above treeline.
The Mt. Baker pro-patrol reported easily ski triggered loose wet avalanches Thursday morning peeling off the most recent 4-6" inches above 4500 ft and running well. Below 4000 feet, the random snow pillow collapse would trigger natural loose wet avalanches due to above freezing temperatures and continuing rain.
Central
No recent observations.
South
No recent observations.
