The lure of sunshine and soft snow today with a lurking buried weak layer (MLK buried surface hoar) is a spooky combination. Before entering avalanche terrain above 2000′ remember the size and consequences of the slides that occurred on Friday on Widowmaker and Jr.’s. Snowpack tests on Saturday in this terrain showed that the layer of surface hoar still has the potential to be triggered. There haven’t been avalanches triggered in other zones but the buried surface hoar has been found throughout the advisory area in snow pits from Crow Creek to Summit Lake. The MLK buried surface hoar is sandwiched between hard layers of snow and in places associated with a melt-freeze crust. In some spots it seems to becoming less reactive in snowpack tests but the fact that the MLK buried surface hoar is so widespread is concerning. Is there a chance of triggering a large unsurvivable avalanche? At this point we are still saying YES. This is the type of weak layer that can’t be underestimated or forgotten.
What to keep in mind as you travel today:
1- The weak layer is around 2-3 feet under your feet or snowmachine.
2- No obvious signs of instability are likely to be seen before a slope releases and it may be the 1st track on the slope or the 20th…
3- If an avalanche is triggered in this deeper weak layer, it can be very large and propagate across the entire slope.
4- There is still a chance of remotely triggering a slab from the ridge, sides or below.
5- Use safe travel protocols: One at a time in avalanche terrain, Stop in safe zones, Watch your partners and Avoid terrain traps!
6- Assess the consequences if the slope slides. The larger the terrain = the larger the potential avalanche!
Crown profile from one of the Widowmaker avalanches that occurred Friday, 2-1-19.
One of the Widowmaker avalanches, 2-1-19. Photo: Jerry Mann
MLK buried surface hoar in a quick pit on Sunburst at 2800′, 2-4-19.
There is obvious wind effect in the Alpine from the winds on Sunday day and Monday night. Lingering wind slabs are still possible today. Look for wind loading patterns and be suspect of loaded slopes. Watch for cracking in the surface snow and stiffer snow over softer snow. Although wind slabs are likely to be shallow, they could be more dangerous if they were to step-down and trigger a large slab that breaks in the buried surface hoar discussed above.
Loose snow avalanches (dry and wet): Watch your sluff in steep terrain on shaded aspects. In steep terrain receiving direct sunshine look for roller balls and small wet loose avalanches.
Cornices: We had a report of a large cornice fall in upper Seattle Creek drainage over the weekend. Give cornices an extra wide berth as they often break farther back than expected.
Glide cracks are opening again. We know of one glide avalanche that has released recently in the Summit zone just north of Manitoba. Look out for glide cracks and limit exposure under them!
Yesterday: Mostly cloudy with light snow showers in the early morning. Winds were easterly 5-15 mph with gusts into the 20s, decreasing to light winds below 5 mph overnight. Temperatures were in the low 20Fs at upper elevations and hovered near 30F at sea level.
Today: Mostly cloudy skies with a slight chance of flurries in the morning becoming mostly sunny by this afternoon. Calm easterly winds throughout the day with gusts up to 5 mph. Temperatures will be in the 20Fs at upper elevations and in the 30Fs at sea level.
Tomorrow: Mostly cloudy skies in the morning, becoming partly sunny in the afternoon. Light westerly winds with temperatures in the 20Fs to low 30Fs. Friday looks to be similar. There is a chance of snow over the weekend and a more active pattern forecast for next week. Stay tuned!
*The Seattle Ridge anemometer (wind sensor) was destroyed. We have a replacement on the way and it should be operational by mid February.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||28||0||0||59|
|Summit Lake (1400′)||27||0||0||27|
|Alyeska Mid (1700′)||27||0||0||53|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||26||*N/A||*N/A||*N/A|