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ARCHIVED - Forecasts expire after 24 hours.
Issued
Mon, January 29th, 2024 - 7:00AM
Expires
Tue, January 30th, 2024 - 7:00AM
Forecaster
Andrew Schauer
Avalanche risk The Bottom Line

Snow has returned to the area, and the avalanche danger has increased to CONSIDERABLE. We should see up to a foot of new snow on the ground before the storm breaks up this afternoon, which has fallen on weak older snow. It will be easy to trigger an avalanche today, and increasing winds through the day will increase the chances of natural avalanches. This is the first time the avalanche danger has increased in 10 days so it’s time to change the way we’ve been traveling and approach the mountains with caution.

Special Announcements

CHUGACH STATE PARK: The front range received a foot of snow in the past 24 hours, which is loading a snowpack with some suspect layers. Expect to see very dangerous avalanche conditions in this zone today.

The National Weather Service has issued a Winter Weather Advisory through noon today.

POSTPONED! The Avalanche Rescue Skills Workshop at the Glen Alps trailhead has been rescheduled to February 3. The event is hosted by the Anchorage Nordic Ski Patrol and Friends of Chugach Avy.

SnowBall 2024:  Mark your calendars for Valentine’s Day, Feb 14 (7-11pm @ 49th St Brewing). Details and tickets HERE. The evening promises costumes, finger food, a rocking band, silent auction, and of course plenty of great company. Join us in supporting Chugach Avy as well as our friends at the Alaska Avalanche School.

Mon, January 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
Tue, January 30th, 2024
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
Tue, January 30th, 2024
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
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

Skiers yesterday reported touchy dry loose avalanches (sluffs) as the snow started to fall in the afternoon. The most recent glide avalanche was Friday night on the front side of Seattle Ridge that buried a large section of the main motorized uptrack (more photos here).

Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Aspect/Elevation
  • 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.

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

Snow has returned to our area, and the avalanche danger has increased for the first time in over a week. We’ve seen 4-8″ snow since yesterday afternoon, and we will likely see another 3-6″ this morning before the storm breaks up this afternoon. With around a foot of new snow falling on weak older surfaces, we are expecting to see dangerous conditions. It is looking like we will see a slight uptick in winds this afternoon, which will keep conditions touchy even after the snow finishes.

It’s time to switch our avalanche brains back on after the recent dry spell and generally stable conditions. The new snow has changed the avalanche picture, and we’re adjusting our travel plans accordingly. Approach the mountains with caution today, avoiding steep slopes while this new snow settles. Keep in mind, this storm buried a variety of surfaces that are not expected to bond well. This includes a variety of crusts and facets at higher elevations, and large surface hoar at lower elevations.

For some areas that end up on the low end of the predicted snow totals, new snow avalanches may be relatively small and it might be reasonable to ease out into steeper terrain. If you are considering getting into steep terrain, anticipate touchy and fast-moving dry loose avalanches (sluffs). These may be getting big enough to bury a person today, and even if they are on the smaller side they can have serious consequences if the carry you through terrain traps like rocks, trees, or gullies.

This was the view at Turnagain Pass yesterday afternoon as the storm rolled in. Photo: Michael Kerst, 01.28.2024

Most of the advisory area should see another 3-6″ today before the storm breaks up. We’re getting a much-needed reset, but Valdez is hogging all of the snow! Graphic courtesy of NWS Anchorage, 01.29.2024

Avalanche Problem 2
  • Glide Avalanches
    Glide Avalanches
  • Aspect/Elevation
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
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.

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

The ongoing glide cycle is still a major concern for the entire advisory area. These avalanches can be avoided by steering clear of runout zones below slopes with glide cracks on them. A fresh blanket of snow on the ground will make it more challenging to recognize some of these cracks, since it will bury the ground where cracks have opened up. As the visibility improves later in the day, you can still spot an active glide crack by looking for an unusual cracked or wrinkled surface. If you can’t see overhead slopes, consider an alternate route. When an alternate route is not an option, you can still reduce your exposure by traveling one at a time below steep terrain and moving quickly through runout zones. With up to a foot of new snow on the ground, this will be good practice anyway, but the added threat of an avalanche failing up to 8′ deep at the ground makes this good travel habit even more essential now.

This glide crack in the Tincan Trees has been open for some time now, but it may be trickier to notice with new snow on the ground. This is just one example of the many active glide cracks in popular parts of our advisory area. 01.27.2024

 

Weather
Mon, January 29th, 2024

Yesterday: We saw cloudy skies with light snowfall yesterday and light easterly winds during the day yesterday. Snow picked up overnight and as of 6 AM there is 4-10” new snow on the ground with only 0.3-0.5” snow water equivalent (SWE). Ridgetop winds bumped up to 10-20 mph out of the east with gusts of 15-25 mph since just after sunset yesterday. Temperatures have warmed significantly since yesterday morning when we were seeing temperatures in the single digits above and below 0 F. There is currently a strong inversion with ridgetop temperatures in the mid 20’s F and valleys sticking in the single digits F.

Today: We should see another 3-6” snow in the first half of the day before clouds start breaking up this afternoon. Winds are expected to pick up slightly as the storm passes, blowing 10-20 mph with gusts of 15-25 mph out of the southeast. Some areas like Seward and Summit will likely see winds getting up to 30 mph at ridgetops this evening. Temperatures are expected to stay in the upper teens to low 20s F for most of the day, but we are looking at another stretch of cold weather this week starting with temperatures dropping right back to -5 to -10 F tonight.

Tomorrow: The frigid air returns tonight, and temperatures tomorrow will likely stay around -5 to -10 F, dropping to -10 to -15 F tomorrow night. Winds should be light out of the west at 5-10 mph, and skies are expected to be partly to mostly cloudy. Expect to see cold temperatures for the rest of the week.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) -2 4 0.3 80
Summit Lake (1400′) -2 6 0.4 N/A
Alyeska Mid (1700′) 1 6 0.4 82
Bear Valley – Portage (132′) 6 10 0.79
Grouse Ck – Seward (700′) 3 6 0.4 56

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 17 ENE 11 27
Seattle Ridge (2400′) -1 NNE 2 6
Observations
Recent Observations for Turnagain Pass
Date Region Location
02/24/24 Turnagain Observation: TinCan Backdoor/ Center Ridge
02/22/24 Turnagain Avalanche: Lynx Creek
02/22/24 Turnagain Observation: Turnagain, Seattle, Mt Ascension
02/21/24 Turnagain Observation: Tincan Trees
02/21/24 Turnagain Observation: Sunburst
02/20/24 Turnagain Avalanche: Tincan
02/20/24 Turnagain Observation: Seward Highway across from Johnson Pass TH
02/19/24 Turnagain Avalanche: Base of Seattle Ridge
02/18/24 Turnagain Observation: Lynx creek
02/18/24 Turnagain Observation: Tincan Trees
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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.