Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, April 23rd, 2022 - 7:00AM
Expires
Sun, April 24th, 2022 - 7:00AM
Forecaster
Andrew Schauer
Avalanche risk The Bottom Line

The avalanche danger is CONSIDERABLE as a warm storm has brought over 2′ of snow to upper elevations and rain on snow to lower elevations, making large human triggered avalanches likely and natural avalanches possible. Two days of above-freezing temperatures will make it likely we could see very large wet slab avalanches failing deeper in the snowpack. Dangerous avalanche conditions will require cautious terrain use today, which means avoiding steep terrain and limiting time spent in runout zones below steeper avalanche paths.

PORTAGE/PLACER VALLEYS: These areas have gotten 2-3′ snow at upper elevations, with 2-3″ rain on snow at lower elevations. This will make it likely to see natural avalanches running long distances into valley bottoms. Very dangerous avalanche conditions exist, and travel in or below avalanche terrain is not recommended.

Special Announcements

End of Season Operations:  Forecasts will be issued on Tuesday, Thursday, Saturday and Sunday through the end of April. If a dramatic change in avalanche conditions occurs on an off day, we will provide a forecast. The final forecast will be on Saturday, April 30th.

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Sat, April 23rd, 2022
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
Considerable (3)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Considerable (3)
Below Treeline
Below 1,000'
Avalanche risk
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wet Slab
    Wet Slab
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Wet Slab
Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

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

Since the snow (and rain) started falling Thursday night, we have received 2-3″ water, which has amounted to 2 feet or more snow in the alpine, and has fallen as almost all rain below 1000′.  This includes 1-1.5″ water in the past 24 hours for Turnagain Pass and Girdwood, and 2.8″ water in Portage. We have seen rain on snow at elevations as high as 1900′, and the old snow did not get a chance to re-freeze ahead of the storm at elevations below around 1800′. With over 48 hours of above freezing temperatures, conditions are primed to see continued very large wet slab avalanche activity similar to the one on Raggedtop Thursday evening.

These large avalanches have the potential to run long distances into valley bottoms, and are nothing to mess with. This means we will need to avoid spending time in avalanche runout zones, as well as on steep avalanche-prone terrain. As Wendy mentioned in yesterday’s advisory, these next few days will most likely mark the start of our springtime shed cycle. We need to navigate the backcountry carefully as things start to fall apart.

Wet Loose Avalanches will be likely at elevations below 1900′, where the storm is finishing as rain on snow. These can be big enough to be dangerous on their own, and they also have the potential to pull out larger wet slabs. Just one more reason to avoid steep slopes today.

Cornices were already massive ahead of this round of stormy weather, and they are being pushed towards their breaking point. As always, be sure to limit time spent traveling under them, and keep plenty of space from the edge if you are traveling along ridgelines.

Glide Avalanches have been releasing across the area, and are expected to continue to release with above-freezing weather. They are large and unpredictable, so be sure to avoid lingering below glide cracks.

The storm from the past two days has put a heavy load on a wet snowpack, with rain on snow up to around 1900′. This will make for dangerous avalanche conditions today. 04.22.2022

Avalanche Problem 2
  • Storm Slabs
    Storm Slabs
  • Almost 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.

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

This storm has brought over 2′ of snow in the upper elevations. Winds have been blowing 20-40 mph out of the east with gusts of 55-65 mph, and are expected to stay strong this morning before slowly calming down later in the day. This is a significant loading event, and will make for continued dangerous avalanche conditions today even as the storm subsides. Human-triggered storm slab avalanches up to 2′ deep or deeper will be likely, with even bigger wind slab avalanches  on upper elevation slopes that have been getting loaded by the strong winds since the storm began.

This storm snow is falling on a mix of weak surfaces. On upper elevation northerly aspects, fresh storm slabs are sitting on dry, faceted snow. The storm buried a crust on all other aspects at elevations above 2000′. On lower elevations, the old snow did not have a chance to refreeze before the storm picked up, which will make for a whole other set of wet avalanche problems (mentioned in problem 1 above).

The avalanche conditions today are very different from what we have been enjoying over the past two weeks. Dangerous conditions will require cautious terrain use. We will need to take a step back and avoid traveling on steep terrain, and limit time spent in avalanche runout zones. If the sun is able to come out for any amount of time this afternoon, be on the lookout for increasing avalanche danger as the new snow heats up.

Yesterday at Tincan was a stark contrast to the conditions we have been enjoying for the past two weeks. 04.22.2022

Click here to view the video from the field yesterday if it doesn’t load in your browser.

Weather
Sat, April 23rd, 2022

Yesterday: Heavy snowfall brought 1-1.5″ water, with rain as high as 1900′. Upper elevations received 1-1.5′ snow since yesterday morning, with over 2′ snow since the storm started Thursday afternoon. High temperatures were in the upper 20’s to upper 30’s F, with overnight lows in the mid 20’s to mid 30’s F. Skies were obscured, with easterly winds of 20-40 mph and gusts of 55-65 mph.

Today: The storm is slowly tapering off, and is expected to bring a trace to 2″ new snow above 1900′. Winds are looking to calm down during the day today, with continued strong easterly winds this morning at 25-30 mph, dropping to around 10 mph this afternoon. Skies will be mostly cloudy, with some brief periods of sun possible in the afternoon. High temperatures will be in the low 30’s to low 40’s F, with lows in the upper 20’s to low 30’s F.

Tomorrow: The weather is looking to quiet down tomorrow, with mostly cloudy skies and high temperatures in the mid to upper 30’s F. Winds will be light and variable, and no precipitation is expected. With continued warm temperatures, we are anticipating very dangerous avalanche conditions next time the sun makes an appearance. Be sure to stay tuned for more.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 34 9 1.5 115
Summit Lake (1400′) 35 0 0.1 34
Alyeska Mid (1700′) 33 2 0.65 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24 ENE 31 65
Seattle Ridge (2400′) 28 SE* 16* 35*

*Seattle Ridge anemometer has been rimed up and not reporting since 4:00 p.m. yesterday.

Observations
Recent Observations for Turnagain Pass
Date Region Location
12/07/22 Turnagain Avalanche: Tincan
12/07/22 Turnagain Observation: Eddies skintrack
12/06/22 Turnagain Observation: Seattle Ridge- Main Bowl
12/04/22 Turnagain Observation: Silvertip
12/04/22 Turnagain Observation: Kickstep Glacier
12/03/22 Turnagain Observation: Seattle Ridge
12/03/22 Turnagain Observation: Seattle Ridge
12/03/22 Turnagain Observation: Superbowl
12/02/22 Turnagain Avalanche: Magnum/Cornbiscuit
11/30/22 Turnagain Observation: Tincan
Riding Areas
Updated Wed, December 07th, 2022

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Placer River
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Skookum Drainage
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Turnagain Pass
Closed
The Forest has issued a closure order for Turnagain Pass due to inadequate snow cover for resource protection. Conditions are being monitored daily. 22” of snow exists at the parking lot. Another storm on Sunday/Monday 12/11 may just do it.
Twentymile
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Seward District
Carter Lake
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Lost Lake Trail
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Primrose Trail
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
South Fork Snow River Corridor
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Summit Lake
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.

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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.