|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.
The already tenuous snowpack is receiving a significant shock to its system. Rain began falling up to 2,000’ overnight. Snow that has fallen since mid December has formed into slabs up to 3 feet in depth. That slab is now losing strength. As that slab loses strength it becomes much more likely for weak layers near the ground to awaken and release large avalanches. Expect entire slopes to avalanche.
Wet slab and wet loose avalanches are possible up to 3,000′ in elevation today.
Heavy wet snow combined with high winds in the upper elevations will create very unstable conditions within the new snow today. Freshly formed slabs up to 2 feet in depth will likely avalanche on their own. High winds will also help to build slabs in areas that don’t normally see much wind (e.g. below treeline and well below typical starting zones). These slabs have the potential to step down to older weak layers near the ground. Expect avalanches to pull out across large areas and run long distances.
Weak layers that make up the bottom of the snowpack proved to be reactive yesterday. Both natural and remotely triggered avalanches were observed. Even if we took today’s weather out of the equation we would still have dangerous avalanche conditions. Given today’s weather, the likelihood of triggering an avalanche in these deeper weak layers is rapidly on the rise. Warm temperatures and rain up to 2,000 feet will help to activate these layers. Dangerous slabs up to 3 feet in depth are likely to take out large areas today.
Red flags abound in the weather category today.
Center Ridge had a high overnight reading of 40 deg F. This is a 10 degree rise in 12 hours.
It is currently raining at Center Ridge with .4 € of water over the past 8 hours, with slightly higher amounts in the Girdwood Valley (.5″ of H2O). This equates to roughly 5 € of new snow at ridge tops. This by itself is a modest amount of snowfall in starting zones. However, let’s take a look at winds.
Sunburst averaging 62 mph out of the East. Gust to 105 mph.
Seattle averaging 48 mph out of the ESE. Gust to 82 mph.
Precipitation, temperature and winds are currently combining to create very unstable conditions.
Today expect as much as 12 € of new snow, with 2 € of snow water equivalent. Freezing level will climb up to ridge top elevation (3,000′). Ridge top winds will be strong all day, in the 65-70 mph range.
Winds and precipitation should taper off on Saturday. The pattern will remain active (continuation of precip) through the weekend and into the early part of next week.
|Observation: Kickstep NE Bowl
|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