|Travel Advice||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 primary concern today is still the deep slab, which is becoming more stable over time. We haven’t had reports of deep slab avalanches since Monday when the last storm system ended. The snowpack is showing evidence of strengthening, but a number of tests consistently still show a low probability of initiating a large avalanche.
This kind of deep slab problem needs to earn our trust. We have growing confidence, but only to a certain point. The consequences of causing a full depth avalanche still deserve our respect and some alteration in our terrain choices. Areas with thinner snow cover are more suspect, and steep rocky terrain may hold the trigger points that could activate a large avalanche.
Now that the deep weak layer has been dormant for a few days we can expect a low possibility of triggering it. A new significant snow load (which is in the weather forecast for tonight) will increase the chances of deep slab activity as additional stress gets added to the weak foundation (see picture below).
The small amount of snow predicted to fall this afternoon will build wind slabs at higher elevations. Based on the timing of this storm it looks like this problem will be minor today, but may build into a significant problem tomorrow.
A blizzard watch is in effect for Girdwood, Seward, and Whittier starting this evening. It appears that this will not have a major effect on the daylight hours today, but it may cause a bump in the avalanche danger by tomorrow. We can expect increasing wind and up to 5 inches of snow by this evening.
If you are wondering how the mountains are doing for snow this year check out the graph below. Our snow depth is slightly above average, and the Snow Water Content measured at 1880 feet at Turnagain Pass (below) is just barely below average.
|11/27/23||Turnagain||Avalanche: Tincan Ridge||Schauer/ Stiassny Forecaster|
|11/26/23||Turnagain||Observation: Road report: Slide with dirt on Repeat offender||Anonymous|
|11/26/23||Turnagain||Observation: Pete’s North||Ben Sullender|
|11/25/23||Turnagain||Observation: Tincan trees||John Sykes Forecaster|
|11/21/23||Observation: Spokane Creek||John Sykes Forecaster|
|11/19/23||Turnagain||Observation: Magnum – PMS Bowl||Schauer/ Cullen/ Jonas Forecaster|
|11/19/23||Other Regions||Observation: Sunnyside/Penguin||Jose Ramos-Leon|
|11/19/23||Turnagain||Observation: Eddies||Andy Moderow|