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The avalanche danger remains MODERATE above 1,000′ on all aspects. Human triggered slab avalanches 1-2′ thick, and potentially larger, remain possible. These are either shallow old wind slabs or larger slabs that break in weak layers deeper in the snowpack. Sunshine may warm southerly slopes today and could contribute to instability on these aspects.
The Summit Lake area has seen more avalanche activity over the past week. Take a look at the Summit Summary HERE.
Hatcher Pass users: Dangerous avalanche conditions exist in this area. Several close calls have occurred over the past few days. Please see the Hatcher Pass Avalanche Center forecast before heading that way.
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. |
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.
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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 |
Date | Region | Location | Observer |
---|---|---|---|
04/16/24 | Turnagain | Observation: Cornbiscuit | Krueger / Matthys Forecaster |
04/15/24 | Turnagain | Observation: Taylor Pass | John Sykes Forecaster |
04/15/24 | Turnagain | Observation: Seward Highway – Tern Lake to Portage | Joel Curtis |
04/14/24 | Turnagain | Observation: Sunburst | T. Olsen-Lund, R. Sullivan I. Adams |
04/14/24 | Turnagain | Observation: Turnagain Pass Snomo | K. Gallaher |
04/13/24 | Turnagain | Observation: Spokane Creek | Everet Megli |
04/11/24 | Turnagain | Observation: Tincan | John Sykes Forecaster |
04/10/24 | Turnagain | Avalanche: Seattle Ridge | Schauer/ Keeler Forecaster |
04/10/24 | Turnagain | Observation: Cornbiscuit South Face | Todd Kelsey |
04/10/24 | Turnagain | Avalanche: Tincan | N. Dumont J. Carlberg |
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