Above 2,500′ moist to dry snow has fallen for two weeks now. We have little information for these upper elevations at this time, but we do know prior to the storm cycle weak faceted snow with crust(s) sat near the ground. Prior to this last warm, wet storm this set-up was very reactive and there were multiple remote triggered avalanches. The slab on top of this weak foundation has now grown to several feet. This presents a deep persistent slab problem and will be guilty until proven innocent. The 1st person on the slope or the 10th might trigger this type of avalanche. It is a total roll of the dice or Russian roulette set-up. Finding the shallow spot could have devastating results. This type of avalanche would be unsurvivable. There may be no obvious clues to indicate instability and digging to find the weak layer could be challenging. We need more time and information to determine the sensitivity and distribution of the deep persistent slab problem. Conservative route-finding will be essential due to the potential for large avalanches.
Below 2500′ where rain fell the snowpack is a mixture of crusts and wet snow. Runnels are present and the facets near the ground are moist to wet and rounding. The cooling trend is locking up the snowpack. Triggering an avalanche is still possible but does not have the same potential for the large destructive deep slabs. Pay attention to your elevation bands today and as always look for signs of instability.
Deep slab avalanches are like messing with a sleeping dragon. You might tiptoe around it but waking the dragon up will be terrible. Avoidance is key!
4-6+ inches of water weight, multiple feet of snow, now rest on top of this snowpack structure observed on December 8th.
In the Alpine there is plenty of new snow to blow around and an additional 2-6″ is forecasted to fall throughout the day. Easterly winds gusting into the 40s will load leeward slopes today and triggering a fresh wind slab will be likely. Look for drifting and cracking and avoid hollow sounding snow. These same slopes may also have a deep slab problem. Triggering an avalanche in the upper snowpack may have the potential step down.
Video from the National Avalanche Center Encyclopedia
Yesterday was overcast with light snow showers on and off throughout the day. Easterly winds were light 5-10 with a few gusts into the teens. Temperatures were in the mid 20Fs to low 30Fs. There was a cooling trend overnight.
Today is forecasted to be mostly cloudy with snow showers during the day with snow likely tonight. 2-6″ of snow expected to fall today and 4-10″ tonight. Temperatures will be in the mid 20Fs to low 30Fs. Winds will be easterly 15-25 gusting into the 40s. Rain/snow line will be approximately 500′ today dropping to sea level tonight.
Tomorrow should see continued snow showers, decreasing winds and cooler temperatures. According to the National Weather Service, “The long term will continue to see rather active weather, though cooler (more seasonable) temperatures should move back in.” #snowtosealevel
* Sunburst weather station is down due to loss of battery power.
** Seattle Ridge anemometer is rimed and not reporting.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||30||0||0||25|
|Summit Lake (1400′)||28||0||0||9|
|Alyeska Mid (1700′)||30||0||0||18|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||**n/a||**n/a||**n/a|
|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: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
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