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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, April 28th, 2024 - 7:00AM
Expires
Mon, April 29th, 2024 - 7:00AM
Forecaster
Andrew Schauer
Avalanche risk The Bottom Line

The avalanche danger will start out LOW and rise to CONSIDERABLE as the snowpack heats up and wet snow avalanches become more likely. This includes wet loose, wet slab, and glide avalanches. Be aware of increasing danger as surface crusts break down and the snowpack becomes unsupportable. If you notice wet and sloppy snow on the surface, head to shaded aspects and be aware of the potential for natural avalanches to release above you.

Special Announcements

That’s a wrap! This is our final forecast for the season. Thank you for sticking with us this year as we expanded our operation, and thank you to everyone who supported us through sharing observations, field days, or making donations to the Friends of the Chugach Avalanche Center. We’ll post our springtime tips tomorrow morning, and continue to publish public observations as you submit them through the spring.

Sun, April 28th, 2024
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
Mon, April 29th, 2024
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
Mon, April 29th, 2024
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

We’re continuing to see wet snow avalanches throughout the area. The most notable activity yesterday included a fresh glide avalanche on Pyramid and a large wet slab near Johnson Pass.

Glide avalanche on Pyramid. This released sometime overnight or in the early morning. Photo: Quinn Predeger, 04.27.2024

Very large wet slab in the Johnson Pass area. Photo: Noah Mery, 04.27.2024

Avalanche Problem 1
  • Spring Conditions
    Spring Conditions
  • Aspect/Elevation
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Spring Conditions
Warmth has a tricky effect on snow. On the one hand it speeds up the stabilization of the snowpack (reduces the chance of slab avalanches). But a SUDDEN rise of temperature increases the chance of slab avalanches considerably. When this warm period is followed by cooling down, then the chance of slab avalanches reduces. Even more so: the more often the temperature changes, the more stable the snowpack becomes when looking at slab avalanches. Once the temperature becomes too warm we have to deal with wet snow avalanches.

Aspect/Elevation of the Avalanche Problem
Specialists develop a graphic representation of the potential distribution of a particular avalanche problem across the topography. This aspect/elevation rose is used to indicate where the particular avalanche problem is thought to exist on all elevation aspects. Areas where the avalanche problem is thought to exist are colored grey, and it is less likely to be encountered in areas colored white.

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

We are expecting another day of mostly sunny skies with warm temperatures, and the main avalanche concerns will be all of the varieties of wet snow avalanches, including wet loose, wet slab, and glide avalanches. Despite the above-freezing temperatures we saw at mid- and low elevations overnight, clear skies should have allowed for at least a light refreeze. This should make for generally safe conditions this morning. However, we should expect to see a quick transition to dangerous conditions as surface crusts melt and the snowpack becomes more unstable as temperatures rise.

The first signs of concern should be a shift from supportable surfaces to loose, sloppy snow. You may also start to see wet rollerballs rolling down the slope. Wet loose avalanches will be the most likely type of avalanche we will see, but we may also see some bigger avalanches. Over the past few days we have seen multiple very large wet slab and glide avalanches, which would have been unsurvivable had they involved any people. Pay attention to changing conditions and increasing danger as temperatures heat up today, and be on the lookout for this transition to happen earlier in the day in light of the warmer temperatures last night.

Cornice Fall: With the warmer temperatures, we will continue to see the massive cornices that have been growing all season continue to break off ridgelines and tumble down slopes. These often entrain a large amount of snow as they fall, and they have the potential to trigger bigger slab avalanches. As always, limit any time spent traveling under cornices.

Thank You for another great season! We appreciate all the support we have from our community, and we are looking forward to doing it all over again next season. We have some more changes in the works as we continue to grow, so be sure to stay tuned in to our website and social media channels for updates throughout the spring and summer. We will also continue to publish observations as they are submitted. Let us know if you get out and see something interesting.

 

Weather
Sun, April 28th, 2024

Yesterday: Skies were mostly sunny with high temperatures in the low 40s to mid 50s F and low temperatures in the upper 20s to upper 30s F. Winds were light out of the east at 5 to 10 mph for most of the past 24 hours, but have switched westerly overnight. No precipitation was recorded.

Today: Skies are expected to remain mostly sunny with light westerly winds at around 5 to 10 mph with gusts around 15 mph. High temperatures should be in the low 40s to low 50s F with overnight lows in the low to mid 30s F. No precipitation is expected.

Tomorrow: The weather is looking to remain quiet tomorrow, with mostly sunny to partly cloudy skies and light winds at around 5 to 10 mph with variable direction. High temperatures should be in the upper 30s to low 50s F, with lows in the upper 20s to mid 30s F. No precipitation is expected.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 44 0 0 81
Summit Lake (1400′) 40 0 0 34
Alyeska Mid (1700′) 46 0 0 90
Bear Valley – Portage (132′) 42 0 0
Grouse Ck (700′) 42 0 0 60

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 35 NE-W 8 24
Seattle Ridge (2400′) 41 var 2 6
Observations
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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.