Deep persistent slab avalanches remain the primary concern in the advisory area. We know the snowpack structure above 3000′ is poor, there is a dense hard slab (3-8+ feet thick) sitting on a variety of weak layers in the mid pack (including buried surface hoar) and old November facets near the ground. Triggering a deep slab is becoming more and more difficult, but is still possible. The most likely trigger spots are thin areas in the snow cover, often near rocks, or where the slope rolls over. High peaks, that see wind, can also be thinner and it is more likely to find the trigger point for a deep slab where some of the slab has been stripped away.
Key points that keep in mind about our current snowpack:
– We have a ‘low probability, high consequence’ situation at the upper elevations for deep slab avalanches. If you do trigger an avalanche it could be huge and unsurvivable.
– Obvious signs of instability are not likely to been seen before a deep slab is triggered (such as whumpfing and cracking)
– Remote triggering is possible
– This issue can simply be avoided by sticking to terrain below 3000’ (which is a good portion of terrain at Turnagain) or choosing low-consequence terrain in the Alpine
Snow pit on Sunburst that illustrates the buried weak layers in the snowpack above 3000′.
Avalanche on Magnum that ran during the storm last week. Slopes that did not slide at upper elevations are suspect. Photo: Andy Moderow
The additional snow we picked up over the past two nights, 5-7″ in Girdwood and 1-2″ at Turnagain landed on already loose surface snow. The surface snow has been quick to sluff on steep slopes and the new snow will just add to the volume of the sluffs (loose snow avalanches). As the sluffs grow larger they could definitely catch a person by surprise, especially on steep, committing terrain.
On the flip side if you encounter stiff snow along ridgelines be on the look out for small pockets of wind slab. The wind has been pretty light but loose snow blows around easily. Pay attention to changing conditions.
The loose surface snow, comprised of surface hoar and near surface facets, which is now buried under the new snow. Photo Allen Dahl
Cornices have grown with the last storms; many have fallen, yet many have not. As always, give these features a wide berth and remember they can break further back than expected. A cornice fall at the high elevations could trigger a large avalanche on the slope below.
Yesterday skies were broken with patches of blue and some valley fog rolling in. Temperatures were in the teens to low 20Fs. Winds were light and easterly. Overnight the region picked up 1-2″ of snow.
Today will be mostly to partly cloudy with snow showers in the morning, 1-2″ of snow possible. Temperatures will be in the teens and low 20Fs. Winds will be light and shift to the NW. Winds will pick up overnight and skies will clear. Temperatures are forecasted to start falling overnight.
Wednesday looks to be clear, sunny and cold with highs in the single digits. Outflow winds could increase during the day. Overnight temperatures will drop below 0F. Thursday day may even be a bit colder and then temperatures should rise Thursday night as a low moves into the gulf and brings a chance of snow showers for the weekend.
*Seattle Ridge anemometer is rimed over and not able to collect wind data.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||21||1||0.1||57|
|Summit Lake (1400′)||14||1||0.1||16|
|Alyeska Mid (1700′)||15||2||0.1||47|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||24||*n/a||*n/a||*n/a|
|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: email@example.com
|Area||Status||Weather & Riding Conditions|
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