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ARCHIVED - Forecasts expire after 24 hours.
Issued
Thu, March 7th, 2024 - 7:00AM
Expires
Fri, March 8th, 2024 - 7:00AM
Forecaster
John Sykes
Avalanche risk The Bottom Line

The avalanche danger is MODERATE at all elevations. Human triggered and natural avalanches 1-2′ deep in areas with active wind loading at upper elevations are the biggest concern. It is also still possible to trigger an avalanche about 1′ deep at the interface with the new snow from Wednesday night in sheltered areas. If the sun comes out today small wet avalanches on solar aspects are likely. We recommend evaluating how well the new snow from Wednesday night is bonding to the old snow surface before committing to steep terrain.

SUMMIT/JOHNSON PASS: The snowpack in the central Kenai is weaker and more concerning than the rest of our forecast zones. There is still a good chance a person could trigger a bigger avalanche on weak snow buried in the upper 2 feet of the snowpack, and a more cautious mindset is recommended in these areas.

Special Announcements

Turnagain Takeover Avalanche Awareness Day – Mark your calendars for our annual Turnagain Takeover day on Saturday March 23, 2024. Come grab a hot dog or burger and chat with the forecast team about current conditions. Local dealers will have demo sleds available and there will be stations to practice your avalanche rescue skills.

Thu, March 7th, 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
Fri, March 8th, 2024
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
Fri, March 8th, 2024
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.
Recent Avalanches

A handful of natural and human triggered avalanches were reported yesterday. In Turnagain there were multiple natural avalanches near Tincan Common that likely released due to a combination of new snowfall and wind loading (see obs here, here, here). Skiers also reported touchy conditions at the interface between the new snow and old snow surface. As far as we know there were no avalanches in deeper layers yesterday, everything reported with within the new snow. The combination of sun and warm temperatures was also causing wet loose avalanches on steep solar aspects and cornice failures along upper elevations ridgelines.

Natural avalanche in Tincan Common. Photo from Anonymous 3.6.24

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

Reports from folks out in the mountains yesterday verified that the overnight storm on Wednesday quickly dropped significant snowfall, with 8-12″ in Turnagain Pass and 12-18″ in Portage/Placer. All the avalanche activity we heard about yesterday was within the new snow, with both natural and skier triggered avalanches occurring approximately 1-2′ deep. Today it will still be possible to trigger an avalanche at the interface between the new snow and old snow surface. At upper elevations winds are expected to pick up in the afternoon to averages of 10-20 mph out of the east, which could form a fresh batch of wind slabs at upper elevations. Keep an eye out for active wind transport, shooting cracks, and small avalanches on test slopes to identify areas with fresh wind slabs.

Since we are now 24 hours away from the end of the storm, the likelihood of human triggered storm slab avalanches in wind sheltered areas should decrease today. However, we recommend evaluating how well the new snow is bonding to the old snow surface before committing to consequential terrain. Below approximately 2000′ there was an icy crust just below the surface prior to the Wednesday night storm, which could cause poor bonding between the new snow and the old snow surface and lead to avalanches in uncommon locations at lower elevations.

Dry loose avalanches (aka sluffs) are likely in steep terrain sheltered from the wind.

Unstable test result, with full propagation in an extended column test (ECT P 7), at the interface of the new snow and old snow surface about 1′ deep from 3200′ on Tincan. Photo from Jonathan Janis 3.6.24

Larger natural avalanche in Todd’s Bowl on Tincan with debris running down to low angle terrain about 1000′ below. Photo from Anonymous 3.6.24

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

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

If the sun comes out again today wet loose avalanches and cornice fall caused by warming in the sun will be an concern. These problems will be most prominent on steep southerly aspects with rocks or vegetation poking through the snow surface. Wet loose avalanches start out small, but can entrain a lot of snow on bigger terrain features as they run down slope. If cloud cover persists today these wet snow problems could be a non-issue, but we have reached the time of year when the sun can rapidly change snow surface conditions on solar aspects. To identify these problems stay aware of how the sun in affecting the snow surface on southern aspects and try to avoid spending time underneath cornices that are receiving direct sunshine.

Wet loose and cornice triggered loose snow avalanches in Hippie Bowl on Tincan at about 3500′. Photo from Anonymous 3.6.24

Weather
Thu, March 7th, 2024

Yesterday: Snowfall stopped yesterday morning and mid and low elevation cloud layer lingered throughout the day with good visibility at higher elevations. Temperatures climbed up to highs in the low 30s F at lower elevations and stayed in the low to mid 20s F at upper elevations. Winds backed off around 11 am yesterday, with averages of 0-10 mph from variable directions for the rest of the day.

Today: No new snowfall is expected today. Cloud cover looks like it will start out mostly cloudy in the morning and might trend towards partly sunny skies in the afternoon. Winds should remain light out of the east averaging 5-10 mph in the morning and increase slightly to averages of 10-20 mph out of the east in the afternoon. Temperatures should start out in the low to mid 20s F and rise to the high 20s to low 30s F.

Tomorrow: Overnight on Thursday into Friday the winds look to switch to westerly and average 10-15 mph with gusts to 20-25 mph. During the day on Friday winds should calm back down to averages of 0-10 mph. No new snowfall is expected. A mix of low elevation and high elevation cloud cover make it very uncertain what visibility will look like, but hopefully there will be enough breaks in cloud cover for decent visibility. Temperatures are expected to cool off slightly on Friday, with high in the mid to upper 20s F at low elevations and low 20s F at upper elevations.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 26 1 0.1 94
Summit Lake (1400′) 24 1 0.1 45
Alyeska Mid (1700′) NA NA NA NA
Bear Valley – Portage (132′) 28 0 0
Grouse Ck (700′) 28 0 0 65

* Alyeska mid weather station not reporting as of 7 am on March 6th, 2024.

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 21 ENE 6 25
Seattle Ridge (2400′) 26 SE 2 10
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.