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ARCHIVED - Forecasts expire after 24 hours.
Issued
Tue, January 9th, 2024 - 7:00AM
Expires
Wed, January 10th, 2024 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger remains CONSIDERABLE above 1,000′. Triggering a large avalanche 2-4′ deep is the main concern. This type of avalanche was triggered yesterday from a ridge and that danger remains again today. The recent storm snow is still bonding to the old surfaces and a cautious mindset is recommended. Additionally, gusty northwest winds today may be enough to create fresh wind slabs along ridgelines.

SEWARD/LOST LAKE:  Strong northerly outflow winds are forecast for this region. Watch for blowing snow and winds loading slopes. Natural wind slab avalanches may occur.

Tue, January 9th, 2024
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
Wed, January 10th, 2024
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
Wed, January 10th, 2024
Alpine
Above 2,500'
2 - Moderate
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

Skies cleared yesterday for not only a decent look around, but the chance for folks to get back into the mountains and along ridgelines. There were several natural avalanches seen from Sunday’s storm (1.5-2.5′ of new snow). These avalanches were both storm snow slabs and loose snow sluffs. Most noteworthy however were a couple human triggered slab avalanches yesterday, the first day after the storm.

Remote triggered slab on Seattle Ridge:  A group of snowmachiners riding on Seattle Ridge remotely triggered a large slab in Main Bowl, photo below. It is unclear if the weak layer was simply the storm snow that had yet to bond, or possibly a layer of old weak snow that sits under the past two storms (around 4 feet deep). Andrew is headed out today to take a look at this avalanche.

Tincan smaller slab:  Skiers along the Tincan ridge were able to trigger a soft wind slab around 18″ deep and 30-40′ wide.

 

Remotely triggered slab avalanche off Seattle Ridge and into Main Bowl. Reported by the group that triggered it and also by another rider in the area who snapped this photo, J Ohms 1.8.24. 

 

Natural slab avalanche seen yesterday in Todd’s Bowl, released tail end of the storm the day before, 1/7. This is the bowl on the north side of Tincan. Thanks to Taz Feldis for the photo. 1.8.24.

 

Natural slab avalanche on the SW face of Max’s Mtn, seen from our FS office in Girdwood yesterday. 1.8.24.

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

It is the second day after Sunday’s storm brought 1.5-2.5′ of new snow to the region. Before this, another storm on Wednesday brought 1-3′ of new snow. All this new snow is excellent news for great riding conditions, but it does come with avalanche concerns. That new snow from Wednesday fell on an older weak surface (near surface facets and some patchy surface hoar). The jury is still out whether that older snow (4 feet or so deep) is capable of producing avalanches. Was it the culprit in the Main Bowl avalanche yesterday? Hopefully we will find out today. But the main story is, two big storms just loaded the snowpack and tip-toeing a bit in case more large slabs are hanging in the balance is a good call. 

Looking for red flags, cracking in the snow or whumpfing in the snowpack, is always important, but the lack of red flags doesn’t mean we are in the clear. Anytime a slab is triggered remotely (meaning from the top/side/bottom of a slope) it tells us there is some kind of weak layer lurking, which can lead to more human triggered avalanches down the road. If choosing to get into bigger terrain, be sure to know your safe zones, watch your partners, and understand there is a lot of uncertainty. Sticking to the smaller terrain features and lower angle slopes to let the pack adjust another day is a great way to avoid an avalanche.

 

Photo taken by the group that believed they triggered this slab. They did not see it in motion, but they did not notice it before, then saw it when they looked back. 1.8.24.

 

Fresh Wind Slab Avalanches:  Watch for the northwest winds to blow hard enough to move snow into fresh wind slabs. Areas that often see the strongest winds with this flow direction are Crow Pass in the Girdwood Valley, Summit Lake, and Seward. Luckily, Turnagain Pass can often be sheltered. That said, Turnagain is interesting because the east side of the Pass (non-moto side) often sees southerly winds due to terrain channeling; so don’t be surprised if you are on Tincan and the wind is from the south.

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

Glide avalanches continue to occur in the region. The photo below is the newest known glide release, seen yesterday on Pete’s South ridge (southern end of Turnagain Pass). It is prudent to keep a close eye for any signs of glide cracks and avoid being under them. If choosing to scoot underneath these, be sure and watch the slope and move as fast as possible, having an exit plan in case the crack happens to release into an avalanche. These are full-depth avalanches and very destructive. They are highly unpredictable and not triggered by people.

New glide avalanche on Pete’s S ridge (SW face). Thanks to Kellie Okonek for the arial photo, 1.8.24. 

 

Weather
Tue, January 9th, 2024

Yesterday:  Partly cloudy skies were over the region yesterday after Sunday’s storm moved out. Ridgetop winds were light (5-10mph) from the east with gusts near 20mph. Temperatures were in the 20’s F in the mid and upper elevations and near 32F at sea level.

Today:  Mostly clear skies and patchy valley fog is forecast today as a ridge of high pressure is building over Southcentral. Moderate northwesterly winds (10-20mph) are expected along ridgetops with some areas seeing stronger gusts. Temperatures are falling in valley bottoms (teens) but look to remain in the 20’sF otherwise.

Tomorrow:  Mostly clear skies and light variable winds are forecast for Wednesday. Some high cloudy may stream in through the the day. Temperatures look to remain in the 20’s F except for in valley bottoms where they should drop into the single digits. Unsettled weather returns later this week and into the weekend.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 22 2 0 95
Summit Lake (1400′) 16 0 0 N/A
Alyeska Mid (1700′) 26 0 0 89
Bear Valley – Portage (132′) 35 0 0
Grouse Ck – Seward (700′) 26 0 0 52

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 18 NE 6 19
Seattle Ridge (2400′) 21 SE 3 8
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.