|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.
As skies cleared this weekend we saw plenty of evidence of big avalanches during last week’s storm. Yesterday skiers in upper Bertha Creek saw the aftermath of the widest propagating avalanches that we’ve gotten photos of for this cycle, and they also noticed an avalanche on Granddaddy that looks like it may have failed close to the ground. All of those look like they failed as the storm was finishing last Thursday. The last known human-triggered avalanche was a small wind-loaded pocket on the south side of Tincan on Saturday.
|Size (D scale)
|Unlikely to bury a person
|Can bury a person
|Can destroy a house
|4 & 5
|Can destroy part or all of a village
After three days in a row of quiet and sunny weather, an approaching low pressure system is bringing easterly to northerly winds with light snowfall today and tomorrow. For now it is looking like most of our forecast area will only get a trace to an inch of snow today, with 3-5″ possible in Portage and Placer. Easterly winds picked up yesterday evening and are expected to continue to blow at 10-20 mph with gusts of 20-30 mph for most of the day today. This will make wind slabs our main concern for the day once again.
Another round of wind slabs has likely formed in the alpine and upper treeline elevation bands, and will be most often found near ridgelines, convex rollovers, and in steep gullies. Be on the lookout for stiffer snow on top of softer snow, and avoid steep slopes with fresh wind slabs on the surface. Testing small but steep pieces of terrain can be a good way to assess this type of problem. If you notice any red flags like shooting cracks or collapsing, you know you have found a dangerous setup. Be careful of how you interpret those red flags- just because you haven’t seen any shooting cracks doesn’t mean the snowpack is good to go, that’s just one piece of information.
This weekend saw a ton of ski and snowmachine traffic at Turnagain Pass, with one small human-triggered avalanche that we know of. This is an encouraging sign. However, we’ve been paying close attention to how the snow is behaving around the Thanksgiving crust (now 2-4′ deep) and we’re starting to see things we don’t like in snowpits. We’ve gotten reports of multiple test pits showing unstable test results on that layer, and suspect it might be headed in the wrong direction stability-wise. For now, it seems it will take more snow or continued faceting at the crust interface to make an avalanche, but it is something we will continue to track closely.
We’re also still paying attention to the layer of facets at the ground in the highest elevations (above around 3500-4000′). This layer is now buried 6-8′ deep in that elevation band, so you’d need to find the perfect thin spot to trigger an avalanche on it. That said, if someone were to trigger an avalanche on the layer it would be huge. The layer seems to be very isolated, but the most problematic terrain will be high elevation, steep, rocky slopes with a thinner overall depth.
Yesterday: Skies were partly sunny with a thin layer of high altitude clouds and some lingering valley fog. Winds were light out of the north before picking up out of the east at around 6 pm at 10-20 mph with gusts of 20-30 mph. High temperatures were in the mid 20’s to low 30’s F with lows in the mid teens to mid 20’s F. No precipitation was recorded.
Today: A weak system moves into the area today, with partly to mostly cloudy skies and some light snowfall possible. Most areas should only see a trace to an inch of snow today, but some places closer to the coast like Portage and Placer should see 3-5” snow with the rain line staying down around 700’. Easterly winds will continue at 10-20 mph for the first part of the day before backing off slightly this afternoon. High temperatures should be in the low 20’s to 30 F, dropping to the upper teens to mid 20’s F tonight.
Tomorrow: Winds should switch to the north tonight, staying light at 5-15 mph with gusts of 10-20 mph through tomorrow. Seward should expect to see slightly stronger winds, especially at higher elevations, with speeds of 15-25 mph and gusts of 20-30 mph. We may see a few more snowflakes tomorrow, with the rain line staying down near sea level. Temperatures will be slightly cooler with highs in the 20’s F and lows in the mid teens to 20 F.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)
|Snow Depth (in)
|Center Ridge (1880′)
|Summit Lake (1400′)
|Alyeska Mid (1700′)
|Bear Valley – Portage (132′)
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)
|Wind Avg (mph)
|Wind Gust (mph)
|Seattle Ridge (2400′)
|Observation: TinCan Backdoor/ Center Ridge
|AAS L1 Turnagain
|Avalanche: Lynx Creek
|Observation: Turnagain, Seattle, Mt Ascension
|Silverton Mountain Guides
|Observation: Tincan Trees
|Dalpes/Thamm/ Schauer Forecaster
|Observation: Seward Highway across from Johnson Pass TH
|Avalanche: Base of Seattle Ridge
|Troy Tempel, Thomas Lees, .Josh Bollaert, Damian Naquin
|Observation: Lynx creek
|Observation: Tincan Trees
|Moderow / Clayton