Several storms this week brought 3-6+’ of snow to the upper elevations and ended on Wednesday. This last storm caused a widespread avalanche cycle including: a very large D3 avalanche on the SW face of Sunburst, and dozens of large wet avalanches in the mid elevations. Above freezing temps were noted in the alpine during this cycle and rain may have reached ~3000’ at some point, but this has not been confirmed with field data. What we do know is this wet snow has frozen into a solid stable crust below 2500’, but in the alpine this moist snow layer gradually goes away and is not obvious due to new snow covering it up. Basically there is an invisible gray line between Treeline and the Alpine where we go from a stable snowpack to a Deep Persistent Slab problem, where several weak layers (buried surface hoar and facets) are sitting below 3-8+ feet of snow. This avalanche problem comes with a lot of uncertainty due to how deeply buried these layers are. It will be impossible to know where the thinner areas of the snowpack are – likely trigger spots. A snowmachine or a person may get away with riding on steeper slopes, but if a thinner area is found, the consequences could be unsurvivable if caught. This is no beast to mess around with. Keeping your terrain choices conservative in the Alpine will be key. This means choosing low consequence terrain and avoiding large steep slopes.
Keep in mind:
Yesterday we investigated the avalanche on Sunburst and found the New Year’s buried surface hoar to be the most likely culprit. This avalanche wraps around the West Ridge near the skin track all the way to the gully below the weather station (~3/4 mile) and filled Taylor Creek up with debris.
Debris in Taylor Creek
Snow pit at 3300′ just above the crown on a W aspect of Sunburst.
Triggering a storm slab in the top 1-3’ of snow is becoming less likely as we move away from the storm that ended Wednesday. Cold temps and benign weather is helping stabilize any mid-storm weaknesses within the new snow. Storm slabs may be lingering in the alpine, above 2500’, on steep to very steep terrain. This is an additional reason to avoid larger terrain and stay off of slopes steeper than 35 degrees.
Cornices have been growing over the last week and could be easy to trigger. Give these features a lot of space and remember they can break further back from a ridge than expected. A cornice fall also has the potential to trigger a very large avalanche on the slope below.
Yesterday skies were clear becoming partly cloudy in the afternoon. Temperatures were between 20-25F and winds were calm. No precipitation was recorded.
Today skies will be overcast and valley fog and low lying clouds are also possible. Temperatures will be in the mid to low 20F’s and may drop into the teens overnight. Ridge top winds are expected to remain light and variable.
Benign weather is expected tomorrow through the weekend with mostly overcast skies and a possibility of snow flurries. Temperatures will be in the teens to low 20F’s and winds are expected to remain light through the weekend.
**Seattle Ridge weather station stopped recording wind data 1/17/18 rime covering the anemometer.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||23||0||0||56|
|Summit Lake (1400′)||17||0||0||15|
|Alyeska Mid (1700′)||26||0||0||43|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||23||*n/a||*n/a||*n/a|
|12/04/19||Turnagain||Observation: Sunburst||A.Johnston-Bloom W.Wagner/ R.Van Luit Forecaster|
|12/03/19||Turnagain||Observation: HIppy Bowl||Nick Langowski|
|12/01/19||Turnagain||Observation: Tincan, All elevations||Eric Roberts|
|12/01/19||Turnagain||Observation: Tincan||Andy Moderow|
|11/30/19||Turnagain||Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge||Eric Roberts|
|11/29/19||Turnagain||Observation: Sunburst Ob #2||Aleph Johnston-Bloom Forecaster|
|11/29/19||Turnagain||Observation: Sunburst Ob #1||Aleph Johnston-Bloom Forecaster|
|11/27/19||Turnagain||Observation: Tincan||Aleph Johnston-Bloom Forecaster|
|11/25/19||Turnagain||Observation: Sunnyside||Graham Predeger Forecaster|
|11/18/19||Turnagain||Observation: Turnagain Pass – Road obs||Aleph Johnston-Bloom Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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