Turnagain Pass Avalanche Forecast

Despite spring being officially underway, there is a cold(ish) winter storm headed in this morning. A wintery mix is expected below 1,000′ with a couple inches of warm snow accumulating. At the higher elevations, roughly 3-5″ of colder snow is expected. This isn’t too much of re-fresh for powder lovers, but it may improve some riding conditions. This is also not too much to drastically change the avalanche conditions, but it is likely to form some shallow wind slabs and create some sluffs in steep terrain.

Ridgetop winds have just picked up from the east and forecast to remain in the 15-25mph range with stronger gusts. That said, wind slabs are likely to form today. These should be on the shallow side, from 6″ to a foot thick. On northerly aspects they could be sitting on a layer of buried surface hoar. Slopes that do not have a sun crust may have a layer of buried surface hoar around 2-6″ below the surface. This was found on Eddies yesterday and suspect to exist in other areas. Wind slabs that form over the buried surface hoar could be a bit larger and propagate wider than expected. Quick hand pits, looking for small ‘feathers’ and easy shears is a good way to suss this out. Wind slabs on southerly aspects may be touchy as well as they will be sitting on a sun crust.

In short: The big issues to watch for are how much new snow falls and if the strong winds are blowing it (or older loose surface snow) into fresh slabs. Additionally, older small wind slabs formed a day ago could be found, as was seen on Eddies yesterday (photo below).

Dry Loose Snow avalanches:  Sluffs in the drier new snow at the higher elevations will be likely. These should be on the smaller side and composed of the few inches of storm snow.

Cornices:  Cornices should grow a bit today with the sticky new snow and strong winds. As always, give them a wide berth and limit exposure underneath them.

Storm Slabs:  There is not quite enough snow forecast for storm slabs to form. However, if the snowfall intensifies more than predicted and over 6″ fall, watch for storm slabs on all aspects due to rapid loading.

Cracking in the snow due to a small wind slab found on Eddies ridge yesterday. 3.20.20. Photo: Joe Stock

The NW should of Magnum Ridge. This is yesterday’s surface and what any new snow will fall on today. Take a look at more images from Turnagain Pass HERE. 3.20.20. Photo: Heather Thamm

Cloud cover overnight has trapped in the daytime warmth from yesterday. This has kept the snowpack at the lower elevations from completely re-freezing. If temperatures remain above freezing today, triggering a wet loose avalanche on these wet and saturated lower slopes will be possible. Keep this in mind in small creek beds and terrain traps in the trees.

Small wet loose avalanche triggered by a snowmachiner descending a lower elevation slope under Seattle Ridge yesterday. Note the saturated surface snow and large roller balls. 3.20.20.

Triggering a large slab avalanche that breaks in weak old faceted snow deeper in the snowpack remains a concern in areas that have a shallow overall snow depth. These areas are south of Turnagain Pass and include Johnson Pass to Silvertip area, Summit Lake and Palmer Creek. Watch for areas that have a harder wind packed layer of snow over weak sugary snow. Although it has been almost a week since the last known avalanche breaking in these weak layers, this lingering issue remains a concern.