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The avalanche danger is MODERATE at all elevations due to Monday’s storm snow combined with moderate to strong winds over the past two days. Human triggered wind slabs 1-2′ thick will be possible. Expect loose snow sluffs in steep protected terrain. Additionally, old weak layers deeper in the pack may be triggered, creating a larger avalanche. Evaluate snow and terrain carefully.
There was a skier trigger avalanche yesterday in Summit Lake. Read the Saturday Summit Summary HERE and current observations HERE.
Lost Lake Trail, Primrose Trail, South Fork Snow River Corridor and 20 Mile are all open for motorized use as of today. At 20 Mile please cross the railroad tracks at the designated spot as you leave the parking area.
If heading to Lost Lake area check out an observation describing a snowmachine triggered avalanche that occured yesterday HERE.
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 |
Yesterday there was evidence of the winds moving Monday’s snow around across the region. Scouring, anti-tracks and drifting were observed, especially along upper elevation ridges. A few small natural winds slabs from right after the storm were observed with the crowns mostly filled in. There were no reports of human triggered winds slab avalanches in the advisory area but there was wind slab triggered in Summit Lake by a party skinning on the Tenderfoot ridge and a snowmachine triggered wind slab in Lost Lake. Northwest winds picked up in the evening and are forecast to remain strong throughout the day today. There is still some snow available for transport. Expect loading and slabs along ridgelines and look for pillowed or drifted snow. Northerly winds can funnel though Turnagain Pass from the South (especially at lower elevations) and there maybe loading on multiple aspects. Watch for shooting cracks and areas with stiffer snow. Steep, unsupported slopes that are loaded will be the most suspect. Slabs may be stiffer and harder to trigger today. They may be initially supportable and then fail above once out onto the slab. Look for blowing snow and pay attention to changing conditions.
Loose snow avalanches (sluffs): On steep slopes protected from the wind expect the new snow to sluff easily. These loose snow avalanches may be fast running and entrain snow quickly.
Sunshine: Remember that it is that time of year when we need to pay attention to the sun. The sun can heat up Southerly aspects, and melt surface snow and cause small point releases in the loose new snow. This will be more of a concern if winds become calm this afternoon. This heating can also cause a slab sitting on a weak layer to become more reactive. Avoid steep solar aspect if you notice the surface snow becoming moist or you see roller balls or point releases under rocks.
Wind effect on Eddies
Skier triggered sluff on Seattle Ridge
Snowmachine triggered wInd slab Lost Lake.
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 |
The overall snowpack structure across the advisory area is poor and it is important to keep in mind that larger slides breaking in persistent weak layers could still occur. The new snow load Monday, combined with the winds over the past two days, has added to the overall weight/stress from the small storms last week. This incremental loading can slowly overload weak layers making them more prone to triggering. Furthermore, avalanches triggered in the upper layers of the snowpack, like a fresh wind slab, have the potential to step down to the buried weak layers. In the upper elevations a layer of buried surface hoar from Jan. 21st continues to show signs of reactivity and in the mid-elevations a layer of facets over a melt-freeze crust is suspect. Observers on Tincan noted finding both layers Monday in their snowpits.
Deep Persistent Slabs: At the high elevations above 3,000′, deeper persistent layers could ‘wake up’ if the wrong spot is found. 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, the Summit Lake area and Crow Pass.
Yesterday was partly cloudy. Temperatures at upper elevations were in the single digits while the valleys were in the teens to low 20Fs. Winds shifted in the morning from SW to NW. Winds were light to moderate during the day and picked up in the evening gusting into the 60s on Seattle Ridge. Skies cleared overnight.
Today will be sunny and temperatures will be in the single digits at upper elevations and 20Fs at lower elevations. Winds will continue from the NW 20-30 mph gusting into the 40s during the day. They are forecast to slowly diminish overnight and into tomorrow.
Sunshine continues Thursday with slightly warmer temperatures and light winds. Clouds move in on Friday and there is a chance of snow over the weekend and into next week. Stay tuned for details!
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
Center Ridge (1880′) | 20 | 0 | 0 | 73 |
Summit Lake (1400′) | 11 | 0 | 0 | 30 |
Alyeska Mid (1700′) | 12 | 0 | 0 | 65 |
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
Sunburst (3812′) | 2 | NW | 9 | 51 |
Seattle Ridge (2400′) | 8 | NW | 25 | 66 |
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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