|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.|
|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|
Remember LOW danger doesn’t mean NO danger! In the periphery of the forecast zone, there are areas that saw up to a foot of snow last week; the majority of the mountains only saw 2-6″ of snow. This snow fell on weak near surface facets and buried surface hoar. There has been one known human triggered avalanche that failed in the facets below the new snow, which was last Thursday in the Placer Valley. As folks head out to enjoy the good weather above the fog and into the further reaches of the mountains, finding another slab that is reactive isn’t out of the question. These would most likely be around a foot thick, pockety and on the smaller side. Wind loaded steep slopes are the most suspect. Otherwise, the calm and cold weather pattern has moved us into the “normal caution” phase of avalanche concerns. These include:
*We can’t be lured into forgetting to look for signs of instability and using good travel techniques. Good habits keep us coming home at the end of the day.
South of Turnagain – Johnson Pass/Summit Lake zone: A very poor snowpack structure exists in these areas. Multiple mid-pack weak layers of facets and buried surface hoar have been found as well as a facet/crust combination in the bottom of the snowpack. No recent avalanche activity and calm weather has allowed the pack to slowly adjust. However, little is know of the high elevation at this point and it will be important to evaluate the terrain and snowpack as you travel.
Sluffs and even small slabs are still possible in steep committing terrain. This is the ‘normal caution’ regime.
Thank you to Brent Byrne for capturing the blue skies above the dense valley fog on Seattle Ridge. Also seen here is the crusty surface conditions with a new batch of surface hoar on top. A bad set up for the future and a new load of snow.
Glide cracks are still slowly opening. Although we have not heard/seen one of these release for over a week, limiting exposure under them remains wise. Known areas with cracks are Eddies, Tincan, Sunburst, Magnum, Cornbiscuit, Lipps, Seattle Ridge, Johnson Pass, Lynx Creek, Summit Lake, Petersen Creek, and Girdwood. This avalanche hazard is unpredictable and cracks can release without warning.
Glide cracks on the SW face of Magnum. The photo on the left with the skin track has the crack that seems to be the most active along this ridge.
Yesterday: Clear skies sat above dense valley fog up to 2,000′. Winds have been light from the west along ridgetops (5-10mph). Temperatures have been continuing to cool yesterday and overnight, valley bottoms have dropped to the single digits and ridgelines are in the low teens.
Today: What looks to be one last clear sky day is on tap. Thick valley fog is expected to remain up to 1,500′ or 2,000′. Ridgetop winds will remain light (5-10mph) but switch to a more easterly direction. Temperatures should remain in the single digits in valley bottoms and in the teens F at the upper elevations.
Tomorrow: Clouds, warming temperatures and a chance for snow showers move in on Monday. The rain/snow line looks to stay near sea level through tomorrow and only a trace to a few inches of snow is expected. Another larger system pushes in Wednesday, bringing warmer weather and more precipitation, stay tuned!
*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||8||0||0||50|
|Summit Lake (1400′)||2||0||0||20|
|Alyeska Mid (1700′)||12||0||0||38|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||17||*N/A||*N/A||*N/A|
|12/06/23||Turnagain||Observation: Eddies||N Dumont|
|12/05/23||Turnagain||Observation: Sunburst||Kakiko Ramos-Leon|
|12/04/23||Turnagain||Observation: Lynx Creek||Schauer / Keeler/ Predeger Forecaster|
|12/04/23||Turnagain||Observation: Sunburst, 2400′ – 3100′ NW ridge common uptrack.||Arnav Verma|
|12/03/23||Turnagain||Observation: Center Ridge||Amy Holman|
|12/03/23||Turnagain||Observation: Magnum||Tony Naciuk|
|12/03/23||Turnagain||Observation: West ridge of Tincan Peak and Peak 4400||Kelli Spencer|
|12/03/23||Turnagain||Observation: Lipps||Paul Schauer|
|12/02/23||Turnagain||Observation: Seattle Ridge||Schauer / Keeler Forecaster|
|12/02/23||Turnagain||Observation: Tincan South Side||Anonymous|