|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.|
A snowmachiner triggered a wind slab avalanche side hilling a NW facing slope in Triangle Bowl on the backside of Seattle Ridge yesterday. The crown was a foot deep. The rider wasn’t caught or carried in the avalanche.
|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|
As skies cleared yesterday evidence of Saturday’s storm was easy to spot with a number of wind slab crowns and cornice falls. Observers across the region noted west/northwest winds moving snow throughout the day, wind crusts and a few human triggered wind slabs. The most notable being the one highlighted above. This wind direction gets channeled through Turnagain Pass as southerly winds at mid and lower elevations, is not well captured by the weather stations and is often stronger in Summit Lake. Today be on the lookout for lingering wind slabs, 1-2′ deep, in steep wind-loaded terrain. Remember the loading patterns might be a bit different from what we have been seeing for most of season from the prevailing east winds. With clear skies and easier travel at upper elevations take this into consideration as you choose terrain. Watch for cracks shooting out from your snowmachine or skis, smooth rounded pillows of snow, and ‘punchy’ feeling stiff snow over weaker snow. Even shallow wind slabs can be quite dangerous in high consequence terrain and hard wind slabs may break above you as you travel out onto the slope.
Cornices: The recent strong winds and wet snow have been ideal for building large cornices and causing cornice falls. There were a number of recent cornice falls observed yesterday that failed on Saturday during the storm. As you travel today keep in mind cornices have a bad reputation for breaking much farther back than one would expect. If you find yourself traveling along ridgelines be sure to give them plenty of space.
Glide cracks continue to open and there were recent glide avalanches observed in one of the Eddies south chutes and on the east side of Raggedtop yesterday. As more and more glide cracks appear remember it is important to limit time spent underneath them. Glide avalanches are totally unpredictable, not triggered by people and are the entire snowpack sliding at the ground. This type of avalanche could be large and unsurvivable if you happened to be in wrong place when one releases. If you see recent glide activity please let us know.
Yesterday: Skies were overcast in the morning and became partly cloudy in the afternoon. Ridgetop winds were WNW 10-20 mph with gusts into the 30s. Temperatures were in 20°Fs at upper elevations and 30°Fs at sea level. Skies cleared overnight, temperatures decreased to the teens and mid 20°Fs and winds became light and easterly.
Today: Clear skies, light to calm east winds and temperatures in the teens to mid 20°Fs. Overnight skies remain clear, temperatures will be in the low teens to low 20°Fs and winds remain calm.
Tomorrow: Another day of clear skies, light winds and temperatures in the teens to mid 20°Fs. Clouds start to build on Wednesday in advance of the next storm.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||29*||0||0||133|
|Summit Lake (1400′)||27*||0||0||45|
|Alyeska Mid (1700′)||27||0||0||112|
Both the Center Ridge and Summit Lake SNOTELS stopped reporting data after 7 pm last night.
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||22||W*||2*||15*|
*Seattle Ridge anemometer started reporting again at 2 pm yesterday.
|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|