|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.|
Yesterday was a day for natural avalanche observations. A natural avalanche was observed in Crow Creek just after 2 pm. Details are unknown but the photo of the power cloud in action is concerning. A very large avalanche that was thought to have been naturally triggered sometime in the last couple days above Luebner Lake was observed from the air. This was the largest avalanche we know of recently. In addition, a few natural avalanches were observed in motion out of the forecast area near Moose Pass and Cooper Landing. Over the past few days we know of 6 skier and/or snowmachine triggered slab avalanches from Girdwood, Turnagain Pass and Summit Lake. No one has been caught to date and several have been triggered remotely. All of these avalanches are failing on weak faceted snow 2-3′ below the surface. Many are being triggered in the mid-elevation band around 2,000′ and outside of wind effect. All of this data is pointing to a dangerous snowpack! Heads up!!!!
|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|
Triggering a large dangerous avalanche on buried weak snow remains a concern today. You might be starting feel like the forecast is a broken record because we keep saying this and the danger is still CONSIDERABLE. Unfortunately signs continue to point to large avalanches being a very real and scary possibility and cautious travel has to be the prudent advice. Wind loading in some terrain over the past week and warm temperatures have made the slab over the weak snow (facets and surface hoar) more connected. Often warm temperatures are associated with healing in the snowpack but this time it is actually making things worse. The slab is more cohesive and it’s increasing the potential size of the avalanche (example being the Luebner avalanche) and the likelihood of triggering an avalanche remotely (from the side, below or above a slope). There have been multiple human triggered avalanches reported this week and some concerning natural avalanches. There is snow and wind in the forecast today and tomorrow. These will add more slab and stress to the snowpack. The message today is again… Weak snow that formed in January is lurking 2-3′ below the surface. Please don’t be the trigger!
Some things to remember with this kind of avalanche problem:
Wind slabs: To add insult to injury… While you are trying to avoid large persistent slab avalanches also be on the lookout for fresh wind slabs in leeward terrain.
Video link HERE.
Yesterday: Mostly clear skies in the morning and then clouds building in the afternoon. Temperatures were in the 20Fs at upper elevations and the low 30Fs at lower elevations during the day and overnight. Winds were westerly 5-15 mph gusting into the 20s. Wind shifted to the east and increased overnight to 10-20 mph gusting into the 40s.
Today: Skies will be cloudy with snow likely and 3-6″ forecast. Below 1000′ may see mixed precipitation. Winds will be easterly 15-25 mph gusting into the 40s. Temperatures will be in the mid 20Fs to low 30Fs. Snow showers will continues overnight with another 3-6″ possible.
Tomorrow: Snow likely with rain at sea level. Temperatures in the mid 20Fs to mid 40Fs depending on elevation. Easterly winds through Turnagain arm could gust into the 60s. Temperatures cool slightly in the evening promoting more snow than rain showers and winds should decrease. There is overall cooling trend starting Sunday evening into next week.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||28||1||0.1||54|
|Summit Lake (1400′)||23||0||0||20|
|Alyeska Mid (1700′)||27||1||0.02||55|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||23||E*||7*||24*|
*Big thanks to the Alaska Avalanche School motorized Level 1 class for cleaning off the Seattle Ridge anemometer (wind sensor) around noon yesterday! Wind data is from after that.
|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|