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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, March 21st, 2022 - 7:00AM
Expires
Tue, March 22nd, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is MODERATE on all aspects above 1,000′. Triggering a slab avalanche between 1-2′ thick remains possible due to a layer of buried surface hoar. These avalanches are most likely to occur on shaded slopes, but can also be triggered on southerly facing slopes later in the day when sun crusts warm. Wet loose sluffs will again be possible on southerly aspects during the heat of the afternoon/evening. Lastly, watch for lingering wind slabs from Saturday’s winds at the upper elevations along with cornice breaks.

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Mon, March 21st, 2022
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Low (1)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Recent Avalanches

There were several human triggered avalanches yesterday. Two people were caught and carried in two of these with one injury. All these avalanches are suspected to have failed on the layer of buried surface hoar that formed on March 16th.
*We thank all these individuals for taking the time to write in.

Seattle Ridge, Zero Bowl/Hidden Bowl: A skier triggered a 12″ deep and very wide propagating slab avalanche (WNW, 2,800′). This slab caught and carried the skier. The skier was not buried, but did sustain a knee injury. See the report HERE.

Goat Mtn (near Super Couloir):  A snowboarder was caught and carried roughly 1,000′ in a slab avalanche in steep terrain off Goat Mtn (S, 4,800′). The slab was estimated at 8″ deep, 300′ wide and running 1,500′. The rider was not buried and uninjured. Report HERE.

Seattle Ridge, Main Bowl:  Three avalanches reported. One was a skier triggered slab on the looker’s left side of Widowmaker slide path (SW, 2500′). Skier was able to ski off slab. The other two were snowmachine triggered on the shaded westerly side of the bowl, just off Seattle Ridge itself, no one known to have been caught. Report HERE.

Placer Valley:  Snowmachine triggered slab around 18″ deep, 100′ wide, running 150′ (W, 2,500′). No one caught. Report HERE.

 

Hidden Bowl (Zero Bowl) in the Seattle Ck drainage. Skier triggered by first person on slope, skier sustained knee injury. Photo by Nick Langowski, 3.20.22.

 

Goat Mtn slab that was triggered by a snowboarder. Rider was carried around 1,000′ and thankfully was uninjured and not buried. Anonymous photo 3.20.22.

 

Widowmaker slab (looker’s left side). Skier was able to ski off slab and was not caught. Anonymous photo 3.20.22.

Avalanche Problem 1
  • Persistent Slabs
    Persistent Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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

With one more day of quiet and sunny weather bringing in the ‘spring’ season, we can expect very similar avalanche conditions today that we had over the weekend – the possibility of triggering a slab up to 2′ deep. The layer of surface hoar that was buried on March 16th is a problem, as proof by the many recent human triggered avalanches. That said, today our hackles should still be up.

Most of these slabs have been on shaded aspects, mainly because that’s the best snow to ski/ride, and there are not sun crusts tying the slope together. However, southerlies in the heat of the day, when the crusts soften, are suspect for triggering a slab as well. The 3/16 buried surface hoar sits roughly 12″ deep at Turnagain Pass and 18+” deep in Placer Valley and Girdwood. We have seen some of these avalanches propagate very wide, especially the slab triggered in Zero Bowl on the backside of Seattle Ridge. Another photo of that avalanche is below and more can be seen in the report linked above.

Very wide propagation in the Zero Bowl avalanche. Photo by Nick Langowski, 3.20.22.

For folks squeaking out one more sunny day before the weather heads back in, not only is it very important to watch for all the regular red flags (recent avalanches?, shooting cracks?, collapsing/whumpfing in the snowpack?), but knowing there is a weak layer under your feet is key. Digging a quick pit to see if you can find the layer is great, but remember it’s hard to see and doesn’t always give us the right clues. We know it is in many areas, it just may (or may not) be very easy to trigger. We need to be sure to keep with safe travel protocol (expose only one person at a time, have an escape route planned, watch your partners closely). Remember, this type of avalanche can break after several people have been on a slope and/or could be triggered remotely. One can always stick to slopes 30 degrees or less if choosing to avoid the issue all together.

To make matters more confusing there is an older layer of buried surface hoar (18″ – 30″ or so deep) from March 2nd. Although this layer has been showing signs of bonding and we have not seen it produce avalanches recently, we are still keeping track of it.

Red Flags to watch for – note the cracking just above the snowmachine track. 3.20.22.

 

Lingering Wind Slabs:  Gusty east winds on Saturday formed shallow wind slabs in the upper elevations. Watching for wind loaded slopes and cracking in the snow around you will help suss out any lingering slab. It is also good to keep in mind that even a small wind slab avalanche could step down to the buried surface hoar and create a larger slide.

Wet Loose Avalanches:  Another warm sunny afternoon could cause southerly aspects to melt enough that human triggered wet sluffs will be possible. Natural wet sluffs may occur as well.

Cornices:  It’s that time of year when warm days can cause cornices to slowly ooze over and become easier for us to break them off. They deserve an extra wide berth. There was near miss with a snowmachiner who triggered a cornice fall and traveled over 1,000′ with his machine. Thankfully, the rider was ok.

Glide Avalanches:  Glide cracks continue to slowly open across the region. Keep an eye out for these and always limit time, or avoid if possible, being under them. They can release into destructive avalanches at any time.

Glide crack slowly opening on the southerly face of Eddies. Photo by James Howery, 3.20.22.

Weather
Mon, March 21st, 2022

Yesterday:  Sunny skies with warm springlike afternoon temperatures welcomed the spring equinox. Daytime highs were in the low 40’s in areas seeing direct sun, yet have cooled back into the teens and 20’sF overnight. Ridgetop winds have been light and variable.

Today:   Sunny skies are again forecast today with possibly some valley fog along Turnagain Arm. Temperatures should again climb from the teens/20’s to near 40 in valley bottoms and in the direct sun by late this afternoon. Winds will be light and variable along the ridgelines.

Tomorrow:  The next series of weather systems is pushing in late tonight and by tomorrow we should have mostly cloudy skies with a chance for a few snow flurries – to sea level. Ridgetop winds will also be on the rise from the east. Thursday looks like the best chance for several inches of snow.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 29 0 0 94
Summit Lake (1400′) 24 0 0 39
Alyeska Mid (1700′) 30 0 0 108

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) N/A* N/A* N/A* N/A*
Seattle Ridge (2400′) 27 variable 5 12

*The Sunburst weather station is being attended to today – cross your fingers it is back online this evening!

Observations
Recent Observations for Turnagain Pass
Date Region Location
05/17/22 Turnagain Avalanche: Sunburst
05/17/22 Turnagain Observation: Tincan Ridge
05/11/22 Turnagain Avalanche: Cornbiscuit and Magnum west faces
05/07/22 Turnagain Observation: Granddaddy
04/29/22 Turnagain Observation: Sunburst wx station
04/28/22 Turnagain Observation: More Turnagain Pass/Summit Lake wet slab activity
04/27/22 Turnagain Observation: Magnum
04/27/22 Turnagain Observation: Girdwood/Summit/Turnagain Road obs
04/24/22 Turnagain Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path
04/24/22 Turnagain Avalanche: Seattle Ridge uptrack
Riding Areas
Updated Fri, May 13th, 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
Closed as of May 1 per Forest Plan.
Placer River
Closed
Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage
Closed
Closed as of April 1st per Forest Plan.
Turnagain Pass
Open
Open. Extended opening through May 31.
Twentymile
Closed
Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake
Closed
Closed as of May 1 per Forest Plan.
Lost Lake Trail
Closed
Closed as of May 1 per Forest Plan.
Primrose Trail
Closed
Closed as of May 1 per Forest Plan.
Resurrection Pass Trail
Closed
Closed as of May 1 per Forest Plan.
Snug Harbor
Closed
Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor
Closed
Closed as of May 1 per Forest Plan.
Summit Lake
Closed
Closed as of May 1 per Forest Plan.

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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.