|Travel Advice||Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.||Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.||Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.||Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.||Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.|
|Likelihood of Avalanches||Natural and human-triggered avalanches unlikely.||Natural avalanches unlikely; human-triggered avalanches possible.||Natural avalanches possible; human-triggered avalanches likely.||Natural avalanches likely; human-triggered avalanches very likely.||Natural and human-triggered avalanches certain.|
|Avalanche Size and Distribution||Small avalanches in isolated areas or extreme terrain.||Small avalanches in specific areas; or large avalanches in isolated areas.||Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.||Large avalanches in many areas; or very large avalanches in specific areas.||Very large avalanches in many areas.|
The last known avalanches were small wind slab avalanches that released during the outflow winds 9 days ago.
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
It is looking like we are returning to a more active weather pattern this week, starting with a quick pulse today that will likely bring 1-4″ snow with southerly winds getting up to 10-20 mph in the alpine. While this light system will not be enough to produce a widespread avalanche cycle, it will be possible to trigger an avalanche on wind-loaded slopes in the alpine. After over a week of clear skies, there is faceted snow on the surface on most slopes. As this weak snow gets buried today the chances of triggering an avalanche will increase. These may be getting big enough to bury a person by this afternoon.
If you are planning on getting out today, be sure to pay attention to changing conditions and increasing danger as the weather picks up. The most likely place to run into trouble will be in steep, high elevation terrain just below ridgelines, on convex rolls, or in steep gullies. Take a minute to step off the skin track to see how conditions are changing. If you feel a layer of dense, stiffer snow on the surface sitting on top of softer snow, you’ve found a wind slab. Watch out for warning signs of unstable snow like cracks shooting out from your feet, or collapsing. For elevations at and below treeline, it is unlikely the wind will pick up enough to increase the avalanche danger.
For those of you that have been following along with the advisories this season, those deeper persistent weak layers that we have been talking about for the past few weeks are still present. The good news is that they are gaining strength, and for now, it is unlikely this light load today will add enough stress to the snowpack to impact them.
Dry Loose Avalanches (Sluffs): In areas that have remained protected from recent winds, it will be easy to trigger dry loose avalanches in steep terrain. It is unlikely these avalanches will get big enough to bury a person, but they can become dangerous in high-consequence terrain.
Yesterday’s recycled powder will turn into today’s weak layer. The faceted snow that has been skiing well for the past few days will start getting buried today, making for reactive wind slabs as the weather picks up. Photo from Seattle Ridge, 12.03.2022
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Yesterday: We had a pretty strong temperature inversion yesterday, with temperatures in the single digits to low teens F in the valleys, and reaching the upper 20’s to low 30’s near ridgelines. There were some high altitude clouds and winds were light out of variable directions.
Today: Things should get a little more active today as a weak system moves in. We should see 1-4″ snow for our forecast zone, with Girdwood seeing a little bit more than Turnagain Pass. The rain level will start as high as 1600′, but it is looking to drop quickly as precipitation picks up. Southerly winds will get up to 10-20 mph in the alpine, with temperatures in the upper 20’s to low 30’s F during the day and in the low 20’s overnight.
Tomorrow: A second round of precipitation is on the way for tomorrow, with another 3-5″ expected starting later Tuesday through Tuesday night. Winds should stay around 10-15 mph and switch to a more easterly direction as precipitation picks up. Skies should remain mostly cloudy through tomorrow night. Temperatures should stay in the 20’s F tomorrow, and it is looking like the snow line will drop to sea level.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||24||0||0||23|
|Summit Lake (1400′)||15||0||0||14|
|Alyeska Mid (1700′)||26||0||0||19|
|Bear Valley (132′)||14||0||0||–|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||SW||3||10|
|11/27/23||Turnagain||Avalanche: Tincan Ridge||Schauer/ Stiassny Forecaster|
|11/26/23||Turnagain||Observation: Road report: Slide with dirt on Repeat offender||Anonymous|
|11/26/23||Turnagain||Observation: Pete’s North||Ben Sullender|
|11/25/23||Turnagain||Observation: Tincan trees||John Sykes Forecaster|
|11/21/23||Observation: Spokane Creek||John Sykes Forecaster|
|11/19/23||Turnagain||Observation: Magnum – PMS Bowl||Schauer/ Cullen/ Jonas Forecaster|
|11/19/23||Other Regions||Observation: Sunnyside/Penguin||Jose Ramos-Leon|
|11/19/23||Turnagain||Observation: Eddies||Andy Moderow|