Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, February 15th, 2022 - 7:00AM
Expires
Wed, February 16th, 2022 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is MODERATE at all elevations and on all aspects. Fresh new wind slabs up to a foot deep could be triggered on wind loaded slopes in the Alpine (above 2,500′) and possibly in exposed areas below this in the trees. Additionally, wet or moist snow sluffs may occur today in the new snow with warming temperatures at the lower elevations and on southerly aspects.

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Tue, February 15th, 2022
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
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
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Recent Avalanches

There were no known avalanches yesterday. The last avalanches were small wind slabs triggered on Saturday.

Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

A quick hitting storm moved up Cook Inlet yesterday evening hitting Anchorage and Hatcher Pass, but just skirting our forecast region. From Girdwood through Turnagain Pass and into the interior Kenai snowfall totals look to be in the 3-6″ range with some upper elevation zones possibly seeing up to 8″. Ridgetop winds were generally easterly with the snowfall in the 20-25mph range with gusts in the 40’s. As of early this morning, the snowfall and winds have tapered off. A break in storms today may allow the sun to make a brief appearance before the next round of snow hits early tomorrow morning.

The main avalanche concern for today will be fresh new wind slabs that formed last night along ridgelines, on the steep portions of mid-slope rollovers and in cross-loaded gullies. These will most likely be in the Alpine where the winds were the strongest, but could also be found in exposed areas in the trees. Wind slabs should be generally easy to see, soft and on the smaller side due to the meager new snow amounts. The larger ones could be a foot or two deep where the winds were strongest at the high elevations. Watch for the usual signs: surface clues (smooth rounded areas where winds have deposited snow), feeling for stiffer snow over softer snow, and watching for cracks that shoot out from you.

On slopes out of the wind at the mid and upper elevations, watch for easy to trigger dry snow sluffs. Additionally, temperatures should be warming today along with a chance the sun could poke through. On southerly aspects and at the lower elevations, we could see roller balls and possibly some shallow wet/moist sluffs. These could occur both naturally as well as be triggered by people.

 

Additional Concern
  • Persistent Slabs
    Persistent Slabs
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.
More info at Avalanche.org

We are continuing to track the snowpack as a whole and the various layers of buried crusts that, in places, have weak snow associated with them. As we’ve been mentioning, shallow snowpack zones are the most concerning and where we are finding these weak layers. These areas are on the far north and south of our forecast zone and extend into the interior Kenai. This includes the Summit Lake area (just to the south of our forecast zone) where both natural and human-triggered avalanches failed on old buried weak layers during the strong winds during the middle of last week.

The photo below is of a snowpit on the south end of our forecast zone near Johnson Pass. We are hunting down where the snowpack goes from fairly stable (thicker pack) to unstable (thinner pack). This pit was more indicative of Turnagain Pass with a thicker snow depth and we could not get any layers to fail. However, at the higher elevations where the winds have stripped the snow over the season, thin unstable slopes could exist. Keep this distribution in mind, especially if you are planning on getting out in the zones that have a thinner snow pack. These layers could be quite stubborn to trigger, but the potential is still there for a large avalanche.

Snowpack on the south end of our forecast zone near Johnson Pass at 2,300′. 

Weather
Tue, February 15th, 2022

Yesterday:  A quick moving storm moved through the region yesterday beginning around 2pm and ending around midnight last night. Snow fell to sea level with 3-6″ across most of the area, including the interior Kenai. Ridgetop easterly winds peaked in the evening averaging 20-25mph with gusts in the 40’s. Winds have quieted overnight to 5-10mph.

Today:  Mostly cloudy skies are expected today with a short break between storms. There is a chance the sun could poke through here and there. Ridgetop winds are forecast to be 5-15mph from the south and west. Temperatures should warm to the upper 20’s at the mid elevations with lower elevations seeing mid 30’sF. The next system looks to move in after midnight tonight.

Tomorrow:  Snowfall and increasing easterly winds should begin in the early hours on Wednesday. By noon, weather models are showing 4-8″ new snow with a rain/snow line close to 500′. A brief break looks to happen Wednesday evening, which will be followed by yet another pulse of moisture on Thursday. This active pattern looks to persist through the week.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 26 3 0.2 91
Summit Lake (1400′) 22 4 0.3 40
Alyeska Mid (1700′) 26 4 0.3 91

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 18 E 14 43
Seattle Ridge (2400′) 20 SE 10 28
Observations
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Riding Areas
Updated Sun, November 27th, 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
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Placer River
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Skookum Drainage
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Turnagain Pass
Closed
The Forest has issued a closure order for Turnagain Pass due to inadequate snow cover for resource protection. Conditions will be monitored daily. Between 16-20” of snow exists at the parking lot. The scheduled opening would have been the Wednesday before Thanksgiving per Forest Plan.
Twentymile
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Seward District
Carter Lake
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Lost Lake Trail
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Primrose Trail
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
South Fork Snow River Corridor
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.
Summit Lake
Closed
Scheduled opening Dec 1st per Forest Plan, contingent upon adequate snow depth for forest resource protection.

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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.