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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, April 25th, 2021 - 7:00AM
Expires
Mon, April 26th, 2021 - 7:00AM
Forecaster
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

The avalanche danger is LOW this morning and expected to rise to CONSIDERABLE as direct sunlight and warm temperatures melt surface crusts and destabilize the snowpack. When the surface snow becomes wet and saturated, triggering a wet loose avalanche will be likely on slopes around 35 ° or steeper. Natural wet loose and wet slab avalanches will be possible with the heat of the day as well. These avalanches have the potential to be large and dangerous. Pay close attention to aspect, overhead hazard, and to changing surface conditions. Avoid being under glide cracks and give cornices a wide berth.

CROW PASS, PORTAGE VALLEY: Natural avalanches are possible and could send debris over summer hiking trails and into the valleys during the afternoon and evening hours. Hiking on summer trails that pass through avalanche terrain is not recommended during these times today and into the week.

MONDAY AVALANCHE OUTLOOK: No avalanche forecast will be issued tomorrow. Expect a similar pattern of a surface freeze overnight tonight and another day of warm temperatures, sunshine and rising avalanche as the snow heats up and looses strength.

Special Announcements

We would like to extend a huge thank you to the National Weather Service Anchorage office for their support of avalanche operations in Southcentral this season!

CNFAIC End Of Season Operations:  Daily avalanche forecasts have ended as our forecast season and funding winds down. We will forecast today, Tuesday, and Thursday this week, and put out our springtime tips this coming weekend. We would be grateful for any observations as our field time has wound down as well – thank you!

Sun, April 25th, 2021
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
3 - Considerable
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.
Recent Avalanches

There were no new avalanches reported yesterday. This was the first day in two weeks that we did not hear about natural avalanche activity. However, temperatures did get into the 60°Fs yesterday an we have another hot sunny day on tap today. As noted above expect the avalanche danger to rise as the snow heats up.

Avalanche Problem 1
  • Wet Loose
    Wet Loose
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.
More info at Avalanche.org

Timing and aspect choices are the keys to having a safe and fun day in the mountains this time of year. Instead of thinking about winter avalanche concerns the heat and direct sun are saying —All right! Stop whatcha doin’ Cause I am about to ruin the powder and the riding that ya used to! (RIP Shock G) —it’s time to monitor crusts, snowpack saturation and understand which aspects are heating up first.

After a night of clear skies and radiant cooling creating a surface crust, temperatures are forecast be in the 50°Fs and 60°Fs again today. If you are venturing out to play in the sun, paying attention to surface conditions and overhead hazard will be crucial. Once crusts soften a little riding can be quite fun. However, triggering a wet loose avalanche will be likely on steep slopes with boot-top (or deeper) wet surface snow. If you are sinking in on your skis or trenching on your snowmachine or punching through with your boots it’s a good idea to get off the slope. Triggering roller balls or small push-a-lanches where the surface snow picks up momentum and entrains more surface snow are a good indicators of increasing hazard. Even a small wet loose avalanche can be dangerous if you get caught and they have the potential to gouge down taking the entire snowpack, becoming large and destructive. In addition, it will be possible to trigger a wet slab on slopes seeing significant warming.  Wet slabs avalanches happen when a weak layer or interface becomes moist or wet. The wet snow loses strength and the snow above fails and avalanches. Wet slabs are often triggered by a wet loose avalanche and are most likely to occur in areas with a thinner snowpack, such as Summit Lake.

As you plan your day think about what slopes are heating up. In addition to human triggered avalanches being likely when the surface snow loose strength, natural wet loose and wet slab avalanches will be possible today. Remember north and east aspects warm first, then south, then west, and last north gets the sun again this time of year.  Steep rocky terrain warms up quickly! Natural roller balls are a sign slopes are heating up. Exit routes require thought as well this time of year. Be careful not to traveling across or under suspect slopes on the way back to the car.

Cornices: Warm temperatures and direct sunshine can destabilize this looming hazard. Cornices will become easier and easier to trigger as time goes on. A cornice fall could trigger a wet avalanche on the slope below. Be aware to not accidentally travel onto one and limit any exposure under them.

 

Crust or no crust? That is the question today. Surface crust on Cornbiscuit yesterday, 4.24.21. Photo: Heather Johnson.

A cornice fall today could trigger another large wet loose avalanche on the west face of Pyramid, photo yesterday 4.24.21. 

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

There have been some large glide avalanches over the last 10 days and there are glide cracks littered across the forecast area. Remember glide cracks can release at anytime. Avoid/limit spending time underneath them. Don’t mess with the brown frown!

Glide avalanches and glide cracks near the Seattle Ridge uptrack, 4.24.21.

Cornbiscuit glide avalanche and cracks, 4.24.21.

Weather
Sun, April 25th, 2021

Yesterday: Skies were mostly clear with high temperatures into the 50°Fs and low 60°s and calm winds. Overnight skies were clear and temperatures were in the 30°Fs and 40°Fs and winds remained calm.

Today: Skies will be clear with high temperatures in the 50°Fs and 60°Fs and winds start out calm and then pick up slightly in the afternoon becoming light and easterly. Overnight skies will be clear, temperatures will be in the 30°Fs and winds remain light and easterly.

Tomorrow: Clear skies continue with high temperatures in the 50°Fs and light easterly winds. This pattern looks to continue until mid week when there is a chance of precipitation.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 43 0 0 94
Summit Lake (1400′) 34 0 0 31
Alyeska Mid (1700′) 39 0 0 106

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 41 E 2 9
Seattle Ridge (2400′) 44 NE 2 5
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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.