|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.
Seward Highway: A large natural avalanche put 10-15′ debris on the Seward Highway north of Girdwood early this morning. No people were involved with the incident.
|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
The latest in our parade of storms moved through the area last night, bringing 6-12″ snow to Girdwood and 4-8″ snow to Turnagain Pass and Summit Lake. Easterly winds have been blowing 15-25 mph at ridgetops with gusts of 35-45 mph, making for dangerous avalanche conditions. It is likely a person could trigger an avalanche up to 2′ deep, especially on slopes with fresh wind slabs. Upper-elevation slopes will have the most reactive snow with the potential for the biggest avalanches. Keep in mind, with up to a foot of new snow in the mountains near Girdwood it may also be possible to trigger a storm slab avalanche on sheltered slopes.
Clouds are expected to break up through the day today, with winds already starting to die down this morning. Don’t let the fair weather catch you off guard- new wind slabs will be reactive through the day. If the sun ends up making an appearance, we will likely see some solar-triggered activity. On the small side this could look like rollerballs falling off trees and rocks, but there is also the potential that small wet loose avalanches will trigger bigger slabs. Be careful with your terrain choices, avoiding steep slopes near ridgelines, below convex rolls and in steep gullies, and be aware of the terrain above you. Pay attention to the classic warning signs of dangerous avalanche conditions- shooting cracks, fresh avalanche activity, and collapsing. With one large avalanche putting debris on the highway just north of Girdwood early this morning, we know we are dealing with a dangerous setup.
Loose wet avalanches: Mixed rain and snow up to 1000′ will make loose wet avalanches possible in the lower elevations.
Cornices: With continued snowfall and sustained moderate winds, cornices continue to get bigger and more sensitive. As always, give them plenty of room when traveling above ridgelines, and limit time spent below them.
There are multiple layers of weak faceted snow associated with crusts that formed earlier in the season that are still giving us cause for concern in the areas with a relatively thin snowpack surrounding our forecast zone. We’ve seen poor snowpack structure in the Crow Creek area near Girdwood, the south end of Turnagain Pass towards the Lynx Creek and Silvertip Creek drainages, and throughout the Summit Lake area. This setup produced avalanches during the avalanche work in Summit Lake on Wednesday, and we saw evidence of natural activity in the Summit area as skies cleared for a moment yesterday.
The good news is that this layer does not appear to be a widespread concern for our core advisory area. If you are planning on getting out in the periphery zones, don’t forget about this poor structure. A relatively small avalanche triggered near the surface will have the potential to step down to weak snow buried deeper in the pack, making a large and dangerous avalanche. We have been getting mixed test results in our snowpits on this weak layer, but the recent avalanche activity is all the indication we need to know the snowpack is dangerous and capable of producing large avalanches.
Yesterday: High temperatures were in the upper 20’s to low 30’s F under cloudy skies. Snow started falling in the afternoon, with 6-12″ in Girdwood, and 4-6″ accumulating in Turnagain Pass and Summit Lake overnight. Easterly winds were blowing 10-25 mph, gusting 40-45 mph, with the strongest winds starting around 8 p.m. last night. Rain made it as high as 900-1000′.
Today: The system is passing this morning, and skies are expected to clear during the day. Winds are already calming down and are expected to stay around 5-10 mph, switching westerly during the day. We might see a trace of precip this morning. High temperatures are expected in the mid 20’s to low 30’s F during the day, with lows dropping back down to the low 20’s overnight. We might see some lingering low level clouds before things clear up later in the day.
Tomorrow: It is looking like another day of quiet weather is on tap for tomorrow, with light westerly winds at 5-10 mph and mostly clear skies. High temperatures will be in the 20’s F, and no precipitation is expected.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)
|Snow Depth (in)
|Center Ridge (1880′)
|Summit Lake (1400′)
|Alyeska Mid (1700′)
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