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ARCHIVED - Forecasts expire after 24 hours.
Issued
Fri, January 22nd, 2021 - 7:00AM
Expires
Sat, January 23rd, 2021 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is MODERATE today above 1,000′. Human triggered wind slab avalanches, 1-2′ thick, are possible on wind loaded slopes 35 degrees and steeper due an increase in east winds last night. Watch for slopes with recent wind deposited snow and those that may see active wind loading today. Human triggered cornice falls are also a concern. The danger is LOW below 1,000′ where a thick melt-freeze crust exists.

The avalanche danger is expected to rise to CONSIDERABLE tonight into tomorrow as another storm approaches.

SUMMIT LAKE: In addition to the wind slab avalanche concern, Summit Lake and the interior Kenai Mtns have a thinner snowpack with buried weak layers. Extra caution is warranted for the added potential of an avalanche breaking deeper in the snowpack.

SNUG/LOST LAKE/SEWARD: A snowmachiner was caught and carried in an avalanche just south of Cooper Landing Wednesday out of the Snug Harbor area, near V-Max hill. The rider was not buried and is OK. Please see their story along with videos HERE; we send them a big thank you for being willing to share their experience with us. This area is out of our forecast zone and we have limited information on the snowpack.

Fri, January 22nd, 2021
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
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.
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

Light snow showers are over most of the forecast area this morning, however they should only account for a few inches before tapering off midday. It will again be the winds that are the main driver for avalanche issues. Easterly ridgetop winds climbed last night into the 30-35mph range for averages and a peak gust at Sunburst weather station of 57mph. They have quieted down somewhat this morning, but should continue to average near 20-30mph before ramping up again tonight as the next system heads in. With a few inches of new snow possible today and any existing snow available to move around, we can expect fresh wind slabs in addition to any lingering slabs from the past couple days.

Wind Slabs: If you’re headed out in hopes the skies break enough for travel above the trees, keep a lookout for any recent (or current) wind loading. Feel for hollow drum-like snow, stiff snow over softer snow and cracks that shoot out from your machine, board or skis. Wind slabs are likely to be near ridgelines, on steep rollovers and in cross-loaded gullies. They could be anywhere from a few inches to a couple feet thick pending on the slope you are on and how much wind it has seen.

Cornices: Be extra cautious of where you are in relation to cornices. This photo below (from Tuesday 1.19) shows the top of the Seattle Ridge motorized up-track with a huge cornice. It’s easy to ride or hike up familiar slopes and forget how close we might actually be to a cornice’s edge that has grown during this month’s stormy weather. Cornices like this exist all over the ridgelines right now and giving them more space than one might think is prudent.

Large cornice along Zero Bowl (Mamma’s Bowl) on Seattle Ridge. Photo taken a few days ago on Tuesday 1.19.21. Beau Gehler.

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Say it isn’t so… Glide avalanches have arrived for the 2021 season. The good news, we are only seeing them in areas not likely to be traveled, but that can all change in a heartbeat, as we know from years past. The photo below shows the glide cracks on the southeast shoulder of Goat Mtn that were releasing yesterday. Cracks also have been seen on the southern lower face of Raggedtop (Girdwood Valley), on the southern slope of Gilpatrick and south of Devil’s Pass trail (Summit Lake area on the Kenai).

Keep an eye out for these ‘brown frowns’, avoid travel under them, and please let us know if you see any!

Glide cracks and release on the shoulder of Goat Mtn seen from Girdwood. The crack to the right of the release avalanched shortly after this photo was taken yesterday afternoon. 1.21.21.

Weather
Fri, January 22nd, 2021

Yesterday: Overcast skies were over the region yesterday with a few flurries here and there. Ridgetop winds were east in the 10-15mph range during the day before increasing overnight to the 30-35mph range with gusts in the 50’s. Temperatures hovered in the mid 20’sF along ridgelines and the low-mid 30’sF at 1,000′.

Today: Skies are cloudy this morning and light snow showers are expected before skies try and break up later today (1-4″ accumulation above 500′, rain below). East ridgetop winds decreased early this morning and are forecast to average between 20-30mph with stronger gusts during the daytime hours. Temperatures are warm and could reach 40F today at sea level but should remain in the mid 20’sF along ridgelines. Tonight, another warm storm moves in with heavy snowfall (above 500′) and strong east wind (35-45mph).

Tomorrow: Heavy snowfall will continue on Saturday with rain creeping up to ~1,000′ midday as warmer air streams in. Strong east winds (35-45mph averages) will also continue with the system. The storm is expected to head out late Saturday night with around a foot of storm total and Sunday is still looking like a possible clearing day.

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 33 tr tr 131
Summit Lake (1400′) 29 tr tr 45
Alyeska Mid (1700′) 32 3 0.3 116

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 23 NE 22 57
Seattle Ridge (2400′) 26 SE 19 32
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.
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