|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.
Cooler weather and a chance for a few snow flurries above 2,000′ should keep most of the springtime rapid warming at bay this weekend (and possibly into next week). That said, we are still seeing a handful of avalanches each day as the snowpack transitions from dry to wet. Most of these have been relatively small wet loose sluffs and glide releases. The most notable however, is a natural wet slab avalanche that occurred Thursday(ish) in the Girdwood Valley (photo/description below). This slide was on a Northerly aspect around treeline and illustrates how all aspects are suspect currently. During the past 2 days there has been some type of avalanche documented on North, West and South slopes (I’m betting there is an Easterly one out there as well).
The key for a safe day in the mountains is knowing what slopes are wet, saturated and unsupportable (unstable and dangerous) and what slopes are frozen (stable). This is not always as easy at it seems. Carefully monitor surface crusts throughout the day and be aware of steep terrain above you that may be heating up faster than you may expect. Steep rocky terrain baking in the sun can begin to produce wet sluffs, which could in turn trigger a wet slab, and send debris to valley bottoms where the surface is still frozen.
WET SLAB, WET LOOSE and CORNICE FALLS – things to keep in mind if you are headed out:
Recent large slab avalanche on Orca Ridge/Big League, North aspect – released sometime close to Thursday, April 27th. This slide looks to have started as a wet loose avalanche then stepped down to the mid-pack and then again to the ground around 1500′.
Skier triggered wet loose sluffs on the Southwest shoulder of Sunburst from Thursday/Friday (old crown from early April storm cycle in background)
Farthest left natural wet loose avalanche on the West face of Magnum is also from Thursday/Friday (April 27/28), many older dark and melted out loose snow avalanches from earlier in the week on the right of the face
Glide cracks are also opening up and releasing on many slopes in the region with the springtime melt-down. At times it can be difficult to tell the difference between glides and wet slab avalanches. But that is beside the point – both are dangerous. The way to manage glide avalanches is to stay out from under any slopes harboring glide cracks! Check out the photo below from the motorized up-track. This slope is notorious for producing glide avalanches. Additional glide avalanche activity is expected today and through the week.
Note the opening glide cracks lower on Eddies West facing slopes?
Recent large glide avalanche on the lower Southwest facing Tincan terrain – in this area several glide cracks have released while several cracks and hanging in the balance.
There are several buried persistent weak layers in the snowpack; ranging from buried surface hoar 2-6′ deep, mid-pack facets and facets near the ground. Shallow snowpack zones such as the Summit Lake area harbor depth hoar near the ground. On upper elevation North, West and Easterly aspects these weak layers could re-activate when the snowpack melts, becomes saturated and loses strength. If significant warming/melting occurs this weekend or into the workweek, keep in mind large slab avalanches are possible – both triggered by a person as well as naturally.
Partly cloudy skies with patches of sun filled the region yesterday before clouds moved in overnight with light precipitation; rain showers up to 1,500′ and some wet flurries above this. Up to .1″ of measureable precipitation fell in certain areas. Ridgetop winds have been moderate from the East, 10-20mph averages and stronger gusts. Temperatures have been cooler with ridgetops in the upper 20’sF and parking lot temperatures around 1,000′ in the low 40’sF during the day.
For today and Sunday: As we remain in between large scale weather patterns we can expect partly cloudy skies with intermittent showers. This should give the area a chance for rain up to 1,500′-2,000′ and snow above – intermixed with patches of sunshine. Ridgetop winds are expected to be light in the 5-10 mph range from the East. Temperatures will continue to be cool with ridgelines in the 20’sF and at 1,000′ in the low 40’sF.
Monday and early next week: A cool low-pressure storm system will move in bringing rain to 1,000′-2,000′ and wet snow above this. Easterly ridgetop winds will increase into the 20’s and 30’s mph. Keep tabs on the recent weather on our weather page along with the NWS forecast discussion!
|Temp Avg (F)
|Snow Depth (in)
|Center Ridge (1880′)
|Summit Lake (1400′)
|Alyeska Mid (1700′)
|Temp Avg (F)
|Wind Avg (mph)
|Wind Gust (mph)
|Seattle Ridge (2400′)
|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