|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
Triggering a large and unmanageable slab avalanche 2-4′ thick remains our primary concern. Evidence of natural avalanches were seen yesterday near Silvertip and in Summit Lake. These avalanches likely occurred during a storm that ended Friday with strong winds and 2-4 feet of new snow across our region. On Saturday, a snowmachiner remotely triggered two slabs on Seattle Ridge from a meadow below the slope, and a skier triggered a slab in Girdwood in the Notch Mtn area. These human triggered avalanches were in the mid elevation bands and on small steep terrain features. Due to poor visibility this weekend little information exists from the Alpine. What we do know is various layers of old faceted snow and buried surface hoar sit under 2-4 feet of storm snow from Friday. These persistent weak layers have been well documented and are wide spread across our region.
Much uncertainty exists as to how our snowpack is adjusting to its new load, and today’s moderate winds will be transporting 3-4 inches of loose surface snow. This is not quite enough wind to anticipate natural activity, but just enough to be adding additional stress to the snowpack where a human could tip the balance.
If you are headed out into the backcountry today things to keep in mind are:
Recent natural avalanche activity on a heavily cross-loaded SE aspect between Silvertip and Moose Mountain. Be aware that the Southern end of Turnagain Pass and Summit Lake have a thinner and weaker snowpack.
Stability tests yesterday in the mid elevation zone of Corn Biscuit showed propagation potential on a layer of buried surface hoar mixed with facets.
A Skier triggered avalanche from Saturday (lookers right side) at 2000’ on a NW aspect of Notch Mountain in Girdwood. No one was caught and the party reported that the slide on lookers left was there before they skied the slope and may have occurred naturally or was triggered remotely from above.
Wind slabs: Shallow wind slabs may be forming on leeward features today due to moderate Easterly winds in the Alpine. Triggering a wind slab will likely be shallow, but could step down to a deeper layer of the snowpack and create a much larger and more dangerous avalanche.
Cornices: Cornices have grown and are suspect for breaking while traveling along ridgelines. Give these an extra wide berth and minimize any time below them. Cornice falls can trigger avalanches on slopes below.
Loose snow: Several inches of low-density snow fell this weekend, and moderate winds along ridges could initiate some loose-dry point releases (sluffs.) Radiation from the sun is not expected to be a factor today, but should we experience a period of clearing skies, small wet-loose sluffs are possible on Southerly aspects in steep rocky terrain.
Yesterday was overcast becoming obscured in the afternoon by snow showers that dumped 4 € of low density snow in Turnagain Pass and Girdwood. Light Northwest ridge top winds (5-15mph) increased overnight to 15-30mph from the Southeast. Temperatures ranged from the upper teens (F) to mid-20F’s.
Ridgetop winds will remain moderate (10-30mph) from the East throughout the day and decreasing to Light by the evening. Scattered snow showers may bring an inch of new snow, but not a lot of accumulation. Skies are expected to be overcast, but patches of clearing skies may occur later in the day and overnight. Daily temperatures may swing from the low-20F’s into the low-30F’s by mid-day.
A showery and active pattern is expected to continue throughout the week with periods of snow flurries, but not much accumulation. Wednesday looks like the first chance for a partial clearing, but lots of uncertainty remains in our daily forecast on timing of several Lows passing through our region. Daily temperatures swings are expected to be in the low-20F’s to mid-30F’s and winds may range from Light to Moderate throughout the week.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||27||4||.2||93|
|Summit Lake (1400′)||23||2||.1||35|
|Alyeska Mid (1700′)||22||4||.2||83|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||22||n/a||n/a||n/a|
|01/20/21||Turnagain||Observation: Sunburst||Johnston-Bloom / Roberts Forecaster|
|01/19/21||Turnagain||Avalanche: Cornbiscuit||Schauer/ Johnston-Bloom Forecaster|
|01/19/21||Turnagain||Avalanche: Sunburst and Tincan||CNFAIC Staff|
|01/19/21||Turnagain||Avalanche: Seattle Ridge||CNFAIC Staff|
|01/19/21||Turnagain||Avalanche: Tincan 2900′ SW aspect below Hippy Bowl.||Kris Marshall|
|01/18/21||Turnagain||Observation: Turnagain Pass Road Obs.||A Schauer Forecaster|
|01/16/21||Turnagain||Avalanche: Tincan Trees||A Schauer Forecaster|
|01/15/21||Turnagain||Observation: Sunburst||Schauer/ Wunnicke Forecaster|
|01/13/21||Turnagain||Observation: Tincan||Johnston-Bloom / Moderow Forecaster|
|01/13/21||Turnagain||Observation: Center Ridge Meadows||Alaska Avalanche School Rec Level 1 Roberts|
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|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.