Today is a transition day. We have had mostly cold, clear weather this week. Snow is forecasted to start falling this morning and winds are increasing, gusting into the 30s. The new snow will be falling on very weak surface snow. There is widespread surface hoar, with near-surface facets below. In the terrain around 2000′ and below, this weak snow is more developed and is sitting on the New Year’s melt-freeze crust. This has the potential to act as a bed surface. As the weather comes in today it will be important to pay attention to changing conditions. Slabs may form quickly, especially in leeward terrain. Quick hand pits or riding small terrain features can help check whether or not the new snow is sticking to the old snow surfaces. In steep terrain the weak surface snow can also act as a few inches of fast moving loose surface snow “sluff” that could catch you by surprise if you’re not expecting it.
Surface hoar in the sunshine on Tuesday at 1700′ on Sunburst, photo: Ray Koleser.
As we anticipate the weak snow on the surface getting buried today don’t forget the old buried weak layers. The chances of triggering a persistent slab avalanche have been decreasing. However, it is not something that should totally be ruled out yet. We know that the snow from the New Year’s storm snow is sitting on either buried surface hoar, buried near-surface facets or in thin snowpack areas, facets near the ground. This means there is poor snowpack structure and a persistent slab set-up above 2500′. Snowpack tests over the past few days have shown variable results but point to the continued potential for triggering an avalanche.
For those riders and skiers headed out today:
Watch Wendy’s Extended Column Test from yesterday, January 10th, on Seattle Ridge. It took some harder hits but still propagated (failed across the weak layer). This layer could still produce an avalanche.
Wendy’s pit yesterday was near her pit location on Sunday. She had very similar results. The slab yesterday was a little deeper.
A poor snowpack structure still exists at high elevations above 3,000’, human triggered large and dangerous, deep slab persistent avalanches are still possible. Weak sugary snow (basal facets) near the ground is creating a low probability/high consequence avalanche problem. Likely trigger spots will be in thinner areas of the snowpack that are connected to large, loaded slopes. Signs of instability will not likely be present and there may be tracks on the slope. The possibility of a deep slab avalanche should still be part of your decision-making before committing to big terrain in the Alpine.
Yesterday was a mixture of obscured to overcast to broken skies. Winds were in easterly 10-20 mph, gusting to 30. There were scattered, very light snow showers in the morning. Temperatures were in the teens to low 20s. Overnight temperatures rose as warm air moved into the area.
Today will be mostly cloudy with snow, 4-9″ forecasted. Winds will be easterly 20-30 mph gusting into the 40s. Temperatures will be in the high 20s. Snow will continue overnight into Friday.
Friday afternoon the temperatures are forecasted to rise and Saturday looks like a shift to liquid precipitation at lower elevations. The pattern of the warm southerly flow combined with a series of low pressure systems could persist into next week.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||26||0||0||42|
|Summit Lake (1400′)||15||0||0||14|
|Alyeska Mid (1700′)||22||0||0||34|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||17||SE||16||31|
|12/06/19||Turnagain||Avalanche: Sunburst||Billy Finley|
|12/04/19||Turnagain||Observation: Sunburst||A.Johnston-Bloom/ W.Wagner/ R.Van Luit Forecaster|
|12/03/19||Turnagain||Observation: Hippy Bowl||Nick Langowski|
|12/01/19||Turnagain||Observation: Tincan, All elevations||Eric Roberts|
|12/01/19||Turnagain||Observation: Tincan||Andy Moderow|
|11/30/19||Turnagain||Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge||Eric Roberts|
|11/29/19||Turnagain||Observation: Sunburst Ob #2||Aleph Johnston-Bloom Forecaster|
|11/29/19||Turnagain||Observation: Sunburst Ob #1||Aleph Johnston-Bloom Forecaster|
|11/27/19||Turnagain||Observation: Tincan||Aleph Johnston-Bloom Forecaster|
|11/25/19||Turnagain||Observation: Sunnyside||Graham Predeger Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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