|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 while folks were out and about we saw evidence of a widespread natural cycle from Saturday night’s storm from Girdwood to Seward. Most of this activity failed within the new storm snow, but there were some avalanches that appeared to fail on deeper weak layers in the Girdwood area.
|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
With another day of quiet weather on the way before things pick up again tomorrow, the main avalanche concerns come from layers that are buried in the snowpack. There are two very different kinds of avalanches that should be on your radar today. The first is the lingering chance of triggering an avalanche failing within low-density storm layers from the snow within the past week. While it is unusual for a storm or wind slab problem to remain reactive for much longer than a day or two after a storm, we saw multiple storm events that left very low-density, cold dry snow buried under layers of warmer, wetter snow that will still be a concern today. These storm layers take a little longer to settle out, and can behave like persistent weak layers for several days following a storm. Although we’re not expecting any major weather today, these lingering instabilities will be something to pay attention to while you’re out. They can be assessed using quick travel tests like hand pits and test slopes, as well as formal stability tests. Warning signs like shooting cracks or collapsing are a clear indicator of unstable conditions, but the absence of these signs should not automatically rule out the problem.
The second thing to be aware of is the potential for triggering a much bigger avalanche failing on weak snow buried near the Thanksgiving crust, now 3-5′ deep in most places. We’ve seen problematic structure in almost every part of our advisory area as well as the surrounding zones. We continue to get mixed test results in our snowpits, but we’ve started to see some avalanches failing on this layer over the past two weeks (see our observation from Girdwood yesterday for an example). There is a lot of uncertainty with this layer. It’s a stubborn weak layer that hasn’t yet produced a widespread cycle, but it is the kind of problem that can lie dormant for weeks before it wakes up to make a big avalanche.
Neither of these problems are straightforward, and both will leave a lot of uncertainty even with a thorough snowpack assessment. It’s the kind of setup where most people probably won’t trigger an avalanche today, but if you were the unlucky one to find the slope that is primed to avalanche, you could find yourself in a really bad situation. Keep that combination of high uncertainty and high consequences in mind while you travel today, and consider staying a bit more conservative with terrain choices than usual given the challenging setup.
Yesterday: Skies were partly to mostly cloudy with decreasing cloud cover through the day. Winds were out of the west at 10-15 mph with gusts of 25-35 mph for most of the day before switching to the southeast and slowing to 5-10 mph overnight. High temperatures were in the 20’s F with overnight lows in the teens to low 20’s F. Summit is the coldest this morning with temperatures in the single digits F. No precipitation was recorded.
Today: We should see another day of quiet weather today, with spotty snow showers bringing an inch or two of snow to some areas through the day. Skies should be partly cloudy with light winds out of variable directions. High temperatures will be in the high teens to low 20’s F, with overnight lows in the mid teens F tonight.
Tomorrow: Active weather returns tomorrow, with the chances for snow picking up during the afternoon and into tomorrow night. We could see 2-5” snow during the day tomorrow, with snow lines staying down around 100’. Seward will likely see closer to a foot of snow during the day. Winds will pick up with precipitation, blowing 15-25 mph out of the east with gusts of 20-30 mph. Snowfall will continue into tomorrow night, with another 6-8” possible by Wednesday morning.
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′)
|Grouse Ck – Seward (700′)
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