In the Alpine, sitting anywhere from 1 to 3′ below the snow surface, is a thin layer of weak snow (buried surface hoar/BSH). An observer yesterday found this layer to still be reactive in a snowpit on Sunburst right around 2500′. This buried weak layer remains a concern. At this point obvious signs of instability may not be observed but the possibility of triggering an avalanche cannot be ruled out. As always use safe travel protocol and choose terrain with consequences in mind i.e. where is the avalanche path and where would I end up if the slope slides? The snowpack profile below illustrates the slab sitting over the weak layer.
Snowpit on Sunburst, December 2, 2018. Observer: Chris Robertson
Snow cover looking south on Turnagain Pass, December 2, 2018. Photo: Allen Dahl
Be on the lookout for wind slabs in steep unsupported terrain. Strong easterly winds on Saturday afternoon may have loaded leeward slopes in the Alpine. It may still be possible to trigger a lingering pocket that could be dangerous. Look for stiff, pillowed snow and cracking and listen for hollow, drum-like sounds.
Yesterday: Skies were overcast and there were very light rain/snow showers. Temperatures were in the mid 30Fs to mid 20Fs. Winds were easterly 10-20 mph with gusts into the 30s.
Today: Cloudy skies in the morning becoming partly sunny. Temperatures will be cooling from the 30Fs into the lower 20Fs as skies clear and colder air moves over the region. Winds will be northeasterly 5-15 mph with gusts into the 20s. Expect overnight temperatures in the low 20Fs and high teens. Clouds will move back in overnight.
Tomorrow: Chance of snow showers and increased easterly winds in the afternoon as the next front moves over the area. The pattern remains active through the week. As usual the temperatures and timing are uncertain. Stay tuned!
*Seattle Ridge wind sensor is rimed over.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||33||1||0.1||13|
|Summit Lake (1400′)||29||3||0.3||2|
|Alyeska Mid (1700′)||33||0||0.19||N/A|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||29||*no data||*no data||*no data|