Douglas Island Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, January 15th, 2024 - 7:00AM
Expires
Tue, January 16th, 2024 - 7:00AM
Forecaster
CAAC Staff
High Avalanche Danger
Travel in avalanche terrain is not recommended. Avoid being on or beneath all steep slopes.
Avalanche risk The Bottom Line

 

 

Avalanche danger isĀ High

Current Conditions: The avalanche danger remains high across the region. The primary concerns are storm and wind slab avalanches. With the recent high winds and heavy snowfall the current conditions are not looking good for those who want to step out into the backcountry. We have received a lot of snow in the past couple of days, as well as sustained high wind speeds with gusts up to 60mph in the past 24 hours. And that’s not all folks, on top of the new snow and heavy winds, there is now a buried freezing rain crust from last night (01/14) that is sure to be a nice surface for new snow to slide on. Also at play here is the thick melt/freeze crust from New Years, which could potentially see some action with enough load placed on it. There has been some faceting noticed around this crust layer which is only being exacerbated by this cold weather cycle right now.

Trend: The trend is expected to remain the same for the next few days. The forecast is calling for more snow and winds.

Outlook: The forecast indicates that the avalanche danger will continue to be influenced by these cold temps, lots of new snow, and high winds. Travelers should stay informed of updated forecasts and be prepared to adjust their plans accordingly.

Mon, January 15th, 2024
Alpine
Above 2,500'
High (4)
Avalanche risk
Treeline
1,000'-2,500'
High (4)
Avalanche risk
Below Treeline
Below 1,000'
Considerable (3)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
High (4)
Treeline
1,000'-2,500'
Avalanche risk
High (4)
Below Treeline
Below 1,000'
Avalanche risk
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Recent Avalanches

The most recent observations of avalanche activity on 01/13 in Dan Moller bowl with widespread activity and easily triggered from above and some were remotely triggered from below on flat terrain.

Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word Size (D scale) Simple Descriptor
Small 1 Unlikely to bury a person
Large 2 Can bury a person
Very Large 3 Can destroy a house
Historic 4 & 5 Can destroy part or all of a village
More info at Avalanche.org

Recent heavy snowfall and winds have come together to give us omnipresent storm slabs!

Storm Slabs develop when fresh snow compacts over a less stable layer or boundary. This weak layer might consist of snow from early in the storm or a poorly adhered interface with the older snow surface. It’s akin to a chain, where the weakest link in a layer of snow formed during a single storm or extended snowy period becomes vulnerable. Storm Slabs often occur when there is minimal or no wind.

Storm Slabs can be challenging to identify because the surface snow often remains soft and powdery. When the new snow has sufficient cohesion, these slabs can trigger shooting cracks and subtle collapses at the junction of the new and old snow layers. Traditional snowpack tests that apply downward pressure (like Compression Tests) are of limited use here, as they often penetrate through both storm slabs and underlying weak layers without effectively pinpointing the issue. Instead, indicators such as tilt tests, ski cuts on small, less consequential slopes, or signs of natural activity on certain slopes offer more reliable clues to the presence of Storm Slabs.

Dealing with and avoiding Storm Slabs is crucial. They pose the greatest risk when they funnel into terrain traps such as forests, gullies, cliffs, or areas where escape routes are limited. Given the soft, low-density nature of these slabs, riders might not immediately recognize when they fail, often underestimating their potential for propagation. Consequently, resulting avalanches can be larger than anticipated. To mitigate the risk, it’s advisable to wait at least a day or two after a storm before venturing into steep avalanche terrain. Typically, Storm Slabs stabilize within a week, so waiting several days after significant snow loading events can significantly reduce exposure to this hazard.

Weather
Mon, January 15th, 2024

Expect to see continued snowfall into Tuesday but tapering off after that. Snowfall is expected to continue around the 22nd. Winds are forecasted to be moderate, which means a lot of snow transport will happen. Expect to see wind slabs on leeward slopes. Temperature is also expected to stay below freezing, which could induce faceting within the snowpack and create surface hoars that could be buried with the next snow event.

 

Key weather links:

Eaglecrest Powder Patch (PPSA2)

Eaglecrest FAA (JECA2)

Mt Roberts Tram (JTMA2)

NWS Juneau, AK Avalanche Weather Guidance

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