|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 first avalanche problem that you will encounter from the trailhead is wet snow. The freezing line is reaching up to 2000 feet or higher. Water saturated snow is heavy and weaker than drier snow. This problem will be found below treeline, in terrain often considered “safer” from avalanche danger. Read more about Wet Slab Avalanches here.
Photo from January 21st showing low elevation terrain and several natural avalanches on Seattle ridge. Photo by Katie Johnston.
Above treeline we are accumulating significant snowfall through this warm storm cycle. The weak layers at or near the ground are now buried fairly deep (4-6 feet) and continue to be a problem for large and dangerous avalanches.
While we continue to have warm temperatures and snowfall, any steep terrain that could produce a dry deep slab avalanche should be avoided. We have many reports from the last 2 weeks of remotely triggered and natural avalanches on these old weak layers. The frequency of these events is decreasing, but the size is increasing as the snowpack builds.
Above 2000 feet we will be getting more snow today. The National Weather Service is predicting up to a foot of new snow at higher elevations. With ongoing snowfall we need to wary of unstable storm snow in the top layers of the snowpack. This will be more pronounced in areas of stiff wind slab.
In the last 24 hours we received roughly 0.5 inch SWE (5 inches snow) at Turnagain Pass and over 1.5 inches SWE (15 inches snow estimate) at Alyeska. Wind was strong yesterday morning, with gusts into the 90s mph, but tapered down to the 30s and 40s for much of yesterday. Temperatures are consistently warm, in the 40s F at sea level and only reaching freezing (32 F) near 2500 feet elevation.
Today, we have another pulse of moisture headed our way. Roughly an inch of water is expected today, with another 1/2 inch tonight. Snow line will be near 2000 feet. Wind is from the southeast from 52-65mph.
This pattern is expected to continue the rest of the week until Saturday when the first break in the weather appears in the forecast.
|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|