|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 last reported avalanches were observed or reported on 11/27-28.
See observations from this week HERE.
Conditions have improved over the past 24 hours thanks to 3-5″ of new snow. Expect a variety of bed surfaces under the new snow to consist of old wind slabs, old firm wind crusts, and low density deteriorating wind slabs at low elevation.
|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
It will be possible to human trigger a persistent slab on all aspects, at mid and upper elevation, on slopes steeper than 30º. Triggering a slab at low elevation is unlikely. Natural avalanches are unlikely.
Yesterday’s 3-5 inches of new snow will not contribute to today’s avalanche problem. The new snow is low density, lacks cohesion, and was deposited without wind. The possibility of triggering a slab up to 3 feet deep still exists in specific locations, most likely upper elevation where weak sugary facets and facet crust layers still exist but are becoming harder to find.
Snowpack depth varies from 1 foot to over 3 feet deep and is generally thicker on northerly aspects where prevailing winds have deposited snow throughout the season. Southerly aspects, where prevailing winds have scoured snow throughout the season, are generally shallower. Shallower areas will be easier to human trigger, and locations with deeper snowpacks will be harder to trigger, but result in larger and more consequential avalanches.
As small incremental storms continue to bury the deeper weaker layers in the snowpack, performing hand shears, probe pole tests, and instability tests will continue to give us valuable information about the potential for propagation. We are trending towards seeing less propagation in our pits.
While this avalanche problem continues to linger, stability also continues to improve. Since the basal facets were buried in early November we have witnessed numerous avalanche cycles with the basal facets responsible as the culprit weak layer. The Thanksgiving warm up provided moisture, warmth, and rain that assisted weak sugary snow to round and increase the stability, especially below 3500 ft. Without any additional significant loading events, expect the stability to continue to strengthen slowly over time.
Avalanche behavior may be difficult to predict. Use safe travel protocols to increase your margin of safety.
3″ of new snow with 0.3″ SWE was reported at 2700′ /Frostbite over the past 24 hours.
5″ new snow with 0.5″SWE was reported at 3550’/IM over the past 24 hours.
NWS AVG Forecast here.
NWS point forecast here.
Marmot Weather Station here.
Independence Mine Snotel here.
Frostbite Bottom Snotel here.
State Parks Snow Report and Motorized Access information here.
XC trail grooming report for Mat-Su, Anchorage, and Kenai here.