It has been 4 days since a very warm storm slammed into our area dropping inches of rain up to 2,500′-3,000′ and several feet of snow above this. Since then, cold temperatures have cemented the wet snow into place and locked up any slab avalanche problem below 2,500′ and 3,000′ in areas. Therefore, our main concern lies at elevations above this where a ‘deep persistent slab’ problem exists. On these upper elevation slopes, a dense hard slab is sitting on a variety of weak layers in the mid pack (buried surface hoar) and old November facets near the ground. Triggering a deep slab will be more and more difficult as the days pass, but still possible. The most likely spots to trigger them are thin areas in the snow cover, often near rocks, or where the slope rolls over. High peaks, that see a lot of wind, can also be thinner and more likely to find a deep slab.
If you are headed out today, and the skies stay clear enough for easy travel above treeline, keep these points in mind:
– This is ‘low probability, high consequence’ situation – often refered to a ‘Scary Moderate’ avalanche danger
– Several tracks may be on a slope before someone finds a trigger spot
– Obvious signs of instability are not likely to been seen (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.
Photo: Old cornice fall and avalanche from 1/16 near the Seattle Headwall region at 3,300′. Steep upper elevation slopes that have not slid are the ones most suspect for triggering a large slab avalanche.
Loose snow sluffs are rocketing down steep slopes as this cold weather continues to loosen and facet the surface snow. If choosing large steep terrain, watch your sluff. At mid elevations where 4-8″ of loose snow sits over a hard crust, sluffs are still likely and although not deep, will run quite far.
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.
Mostly sunny skies with thick mid-elevation and valley fog filled the area yesterday. Temperatures were chilly, generally in the teens at all elevations. Overnight temperatures have dropped into the single digits in many valley bottoms and mid-elevation locations. Winds over the past 24-hours have been light and variable.
Today, we should see a slow climb in temperatures as light Easterly flow brings clouds and a chance for snowfall. By late today, an inch of snow is possible at all elevations (including sea level). Overnight, another 2-4″ is possible, again at all elevations. Temperatures are slated to climb into the upper teens at most locations. Winds are expected to be 5-10mph from the Northeast.
Tomorrow, Monday, light snowfall is possible, but little accumulation is expected. Skies also may clear a bit. Winds look to remain light and temperatures will be on a downward trend.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||12||0||0||54|
|Summit Lake (1400′)||10||0||0||15|
|Alyeska Mid (1700′)||15||0||0||43|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||10||N||calm||16|
|12/10/19||Turnagain||Avalanche: Tincan and Sunburst from the air||CNFAIC Staff|
|12/10/19||Turnagain||Observation: Tincan||Nancy Pfeiffer|
|12/08/19||Turnagain||Avalanche: Tincan||Ryan Van Luit Forecaster|
|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|
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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