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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, April 10th, 2022 - 7:00AM
Expires
Mon, April 11th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

There is an overall LOW avalanche danger for the Turnagain Pass forecast region. Low danger does not mean no danger and there are a few things to keep a lookout for. First, small slabs might still be triggered on steep upper elevation northerly aspects. Cornices, give these an extra wide berth, they are large, warming up, and could be close to failure. If the sun melts the surface crusts enough, small wet loose avalanches are possible on southerly aspects.

Despite the unlikely nature of triggering an avalanche today, we still need to pay attention to any red flags and remember our safe travel protocol. Good habits keep us safer. Expose one person at a time, have escape routes planned, and watch your partners closely.

Sun, April 10th, 2022
Alpine
Above 2,500'
1 - Low
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
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

There was one report of a shallow slab avalanche on the Seattle Headwall yesterday. It was triggered by a snowboarder, who was able to ride off the slab. It was on a NE aspect around 3,400′ in elevations. It was reported at 8-12″ deep, 70-90′ wide. (Video HERE).

There was also a report of a large cornice fall in Goldpan (upper Bertha Creek drainage). It is unknown when this occurred, but it looked to be in the past couple days.

Snowboarder-triggered slab referred to above on the Seattle Headwall. Photo Graham Predeger, 4.9.22.

 

Large cornice fall in the Goldpan area that lies in upper Bertha Creek. Unknown time of release, but most likely during the past two days. Photo by Nick D’Alessio 4.9.22.

Avalanche Problem 1
  • Normal Caution
    Normal Caution
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.

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

Another brilliant sunny day is on tap with light to moderate northwest ridgetop winds. With several days of generally quiet weather and a generally stable snowpack, we are now in a Normal Caution regime. This doesn’t mean we can turn our brains off though. There are always wintertime avalanche hazards anytime there is snow on the slopes. Bulleted below are the main ways someone could find a mishap.

Shallow slabs on upper elevation northerly aspects:  There could be either some lingering wind slabs or a lingering soft slab sitting on a weak layer in these specific areas (high elevation shaded slopes). The snowboarder triggered slab is a perfect example of a small (ish) avalanche that can occur. Even a small slab can have big consequences if it knocks a person down steep rocky terrain or cliffs, for example. Look for those classic signs of wind loading, smooth rounded pillows, hollow feeling snow, and cracking in the snow around you.

Cornice Falls:  The recent large cornice fall in Goldpan is a good reminder to really be extra cautious when traveling along ridgelines. These can pull back much farther than one might expect and so we really do have to give them a wide berth. It’s also good to remember that warming temperatures in the afternoon can add to the instability.

Wet loose avalanches:  The sun may heat up southerly aspects enough today to melt the top few inches of the surface crusts. It’s that time of year to pay attention to whether or not the surface is becoming wet and saturated. If there are several inches of loose wet snow, it’s time to head to a cooler slope. Wet avalanches are likely to be small today, but could become larger as the week progresses with steadily increasing daytime temperatures.

Glide avalanches:  Watch for glide cracks and limit any time under them. We have seen a few glide cracks release into avalanches in the region. There are several cracks along Seattle Ridge, Tincan, Eddies, and elsewhere.

Weather
Sun, April 10th, 2022

Yesterday:  Sunny skies were over the region yesterday with somewhat cool temperatures. Daytime high’s reached the mid 30’sF at low elevations and 20F along ridgetops. Overnight low’s are in the teens. Ridgetop winds were light, 5-10mph with gusts near 20mph at most from the NW.

Today:  Another sunny day is on tap, with slightly warmer temperatures. Overnight low’s are again in the teens and should climb to 40F in the parking lots and the mid 20’sF along ridgelines. Ridgetop winds will remain NW in the 5-15mph range with stronger gusts.

Tomorrow:  The ridge of high pressure over the area bringing these clear skies should remain through most the work week. Ridgetop winds should remain northwesterly through Monday, then look to be light and variable. Temperatures will be on a steady rise through the week as well.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 26 0 0 113
Summit Lake (1400′) 22 0 0 40
Alyeska Mid (1700′) 25 0 0 N/A

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 15 NW 7 15
Seattle Ridge (2400′) 21 NW 5 11
Observations
Recent Observations for Turnagain Pass
Date Region Location
03/27/24 Turnagain Observation: Tincan Trees
03/26/24 Turnagain Observation: Cornbiscuit
03/25/24 Turnagain Observation: Tincan
03/22/24 Turnagain Avalanche: Magnum Northwest Aspect
03/21/24 Turnagain Observation: Sunburst
03/21/24 Turnagain Observation: Tincan Proper North Aspect
03/20/24 Turnagain Avalanche: Seattle Creek Drainage
03/19/24 Turnagain Observation: Tincan CFR
03/18/24 Turnagain Avalanche: Tincan – Eddies – Seattle Ridge
03/18/24 Turnagain Observation: Tincan
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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.