|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|
Persistent Slabs: Despite the mostly quiet weather and lack of people triggering avalanches over the past week, triggering a slab avalanche up to 2′ or more remains our main concern for President’s Day. These slabs are becoming more difficult to trigger with time, but a large and unmanageable slide is still possible. Between 1 and 2′ below the surface is the Jan 21 layer of buried surface hoar with weak facets directly below. This layer continues to show signs of reactivity. Red flags may not be present before a slope releases and snow pits can be misleading. Simply the knowledge there are weak layers below your feet or snowmachine should not be forgotten. Add sunshine and calm winds in the forecast today, and that ‘likelihood of triggering’ could increase slightly – both from increased traffic (triggers) and from sunshine affecting Southerly facing slabs. The most likely place to find these are slopes that have not seen significant traffic this season.
Sunshine: It’s that time of year when we need to pay attention to the sun. On calm days the sun can heat up Southerly aspects enough to melt surface snow. This heating can also cause a slab sitting on a weak layer to become more reactive. Keep this in mind if you are enjoying Southerly aspects later in the day.
Wind Slabs: Watch for old wind slabs that could pop out from you on steep slopes. Steep rocky terrain where the slab is not supported from below are the most suspect. In general, most wind slabs are fairly well locked into place.
Cornices: Don’t forget about giving cornices wide berth at all times. Also, sunshine can be a big factor in de-stabilizing these during the afternoon/evening hours.
Old lingering wind slabs and cornices may become easier to trigger/fail with daytime warming and direct sun. Image from Warm-up Bowl on Seattle Ridge, Saturday, 2/17.
As you plan your day, keep in mind that there are deeper persistent layers that could ‘wake up’ if you find the right spot above 3,000′ in the Alpine. At these high elevations, old weak layers of facets and buried surface hoar sit in the bottom half of the snowpack. This structure is most pronounced in places with a thin overall snow cover, such as the South end of Turnagain Pass and the Summit Lake area.
Overcast skies with light snow flurries were over the region yesterday. Most areas only picked up a trace of new snow, but a couple inches may be found at upper elevations. Ridgetop winds were generally light with moderate gusts from a Southerly direction (5-15mph) during the day and have decreased to light and variable overnight. Temperatures dropped from 30F to the upper teens along ridgetops late in the day yesterday. Valley bottoms have remained warm, in the 20’sF, with cloud cover limiting a nocturnal inversion.
For today, President’s Day, skies should clear this morning and a mostly sunny day is expected. Ridgetop winds look to remain light from the Northwest. Temperatures should warm to the upper 20’sF along ridgetops with daytime heating and valley bottoms to around 30F.
Tomorrow, and through the mid-week, partly cloudy skies are forecast with the possibility for Westerly winds to increase on Wednesday before a chance for snow on Thursday. Stay tuned.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||30||trace||0||63|
|Summit Lake (1400′)||26||trace||0||25|
|Alyeska Mid (1700′)||27||trace||0.01||56|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Sunburst (3812′)||22||variable||5||One gust to 37|
|Seattle Ridge (2400′)||25||ESE||12||27|
|11/30/20||Turnagain||Observation: Tincan- above treeline||Eric Roberts|
|11/29/20||Turnagain||Observation: Sunny Side||Peter Wadsworth|
|11/29/20||Turnagain||Observation: Overflight Recon Turnagain Pass||Silverton Mountain Guides|
|11/29/20||Turnagain||Avalanche: Sunburst||Alexa Dobson|
|11/28/20||Turnagain||Observation: Tincan trees||Bob Lieberman|
|11/28/20||Turnagain||Observation: Tincan Trees||Tully Ward-Hamer|
|11/28/20||Turnagain||Avalanche: Seattle Ridge Flats||W Wagner Forecaster|
|11/28/20||Turnagain||Observation: Tincan Treeline||Eeva Latosuo|
|11/28/20||Turnagain||Observation: Sunny Side||Peter Wadsworth|
|11/27/20||Observation: Sunburst||Andrew Schauer Forecaster|
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: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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.