As they say, timing is everything. Yes, it is still March for a couple more days…but the snowpack has been forced into a springtime transition, similar to what is typically seen in late April. Cool mornings with a frozen snow surface below 3,000′ harbors a low avalanche danger. By noon the day is heating up and crusts are softening on East aspects, 1-3pm South aspects and 3-5pm on West aspects. Once the crusts melt away and your boot easily sinks into mushy wet snow, your stay is overdue and it’s time to get onto shaded slopes or off the one you are on and well away from runouts.
Wet loose and even wet slabs are likely to be triggered by people once the snow surface becomes soft and unsupportable. This was seen yesterday on Seattle Ridge. Check out the photos below. These slides can be small and easily escaped. They can also turn into large, destructive and unmanageable avalanches. The larger the terrain the more likely a small wet avalanche can grow into a large and scary one. These types of avalanches can be easily avoided if sticking to slopes that are still cool with a supportable crust or on shaded northerly aspects.
Seattle Ridge Up-Track: Heads up late in the day!
Thank you to Sean Fallon (left photo) and Troy Tempel (right photo) for sending in these images of the Seattle Ridge motorized up-track. This ‘small-ish’ avalanche was triggered yesterday by a snowmachiner while descending through the trees above the uptrack. The rider was able to sidehill off the slab and was not caught. The debris entrained additional snow as it ran downslope, gaining momentum, and crossed the up-track.
In the upper elevations, above 3000’, mostly dry snow exists. Southerly aspects are seeing the effects of the sun and sport a sun crust in the morning that is typically softening later in the day. Under the 5-10 feet of settled storm snow, from the mid-March stormy weather, sits a somewhat questionable old layer of facets/buried surface hoar and crusts. Many avalanches released on this layer during the storms, yet only a few avalanches have been seen since skies cleared – and these have been large. The last slab we know of was in Summit Lake on Butch Mtn. This was most likely triggered naturally, possibly by a cornice fall, we believe on Tuesday night or Wednesday (March 25/26). Although in dry upper elevation snow, the slope was being impacted by direct sunshine and warm temperatures; a contributing factor.
If headed out for a long day in the hills, keep in mind deeper weak layers could be lurking and sunlit slopes are the most suspect. Some good rules of thumb are:
For anyone that missed this photo yesterday. This is the natural slab avalanche on Westerly facing Butch Mt in Summit Lake.
Don’t underestimate the glide avalanche problem! Many glide cracks have avalanched over the last few days. The Southeast face of Seattle Ridge looks like a war zone with several trademark brown streaks left from glide avalanches. Remember, glides are very unpredictable and fail at the ground pulling out the entire season’s snowpack. Many cracks are opening up in popular terrain and avoiding/limiting exposure under these is strongly recommended.
Glide avalanche in Lynx Creek, released yesterday (Mar 28). Note how destructive even a small glide avalanche can be. The initial debris gouged to the ground on the descent, picked up more of snowpack in its the path, and sent the total debris far down the slope into low angle terrain.
Yesterday: Sunny skies were over the area once again. A few convective clouds did develop due to moister air moving through along with the evaporation of the snowpack. Temperatures hit the mid 40’sF at the mid and lower elevations, while slopes above 3,000′ saw temperatures remain just under 30F. Ridgetop winds have been light and variable.
Today: Mostly sunny skies are forecast with a chance for some low clouds this morning before burning off this afternoon. Temperatures should climb from ~30F into the mid 40’sF in the mid and lower elevations with high elevations reaching 30F. A light Northerly breeze is expected along ridgetops (~5mph).
Tomorrow: Sunny skies and warmer air aloft looks to stream in tomorrow, pushing temperatures along 4-5,000′ ridgelines into the low 30’s F. Ridgetop winds are expected to remain light and variable. Weather models are pointing to a breakdown in the ridge of high pressure entrenched over Southcentral Thursday. Until then, sunny skies, warm temps and light winds should persist. Stay tuned!
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||37||0||0||68|
|Summit Lake (1400′)||36||0||0||22|
|Alyeska Mid (1700′)||37||0||0||62|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||33||variable||2||6|