A storm that deposited 2 feet of snow in the higher elevations 2 days ago has left slabs that are generally well bonded to underlying surfaces. While this bonding has been good in recent tests, we saw natural slab activity after the storm had subsided. Yesterday this occurred mainly on steep slopes that were receiving direct sun. More of the same can be anticipated today. Factors that will increase the likelihood of triggering will be slopes over 35º and approaching 40º, heating from direct sunlight and large triggers such as groups.
We have limited data from North facing terrain. As such it will be important keep slope angles 35 or lower if you find yourself on terrain facing the North half of the compass.
Natural slab activity on Seattle Ridge on steep sunlit slopes observed yesterday, April 10th.
2′ Slab with a close up of the crown. Starting zone ~2,300′ SE aspect
A view of the debris of the avalanche pictured above. Avalanche ran ~1,000′ vertical.
Both wet loose and wet slab activity can be expected on steep sunlit slopes. In the higher elevations, sun will impact slopes and “grease” the interfaces between the slab and bed surfaces. Those bed surfaces are crusts on East, South and West aspects.
In the lower elevations, a warm and weak snowpack will allow for the chance of medium to high volume wet loose avalanches during the heat of the day. Volume will be dictated by terrain; more sustained steep slopes will produce more debris.
Pay attention to the temps and sun today. Dial back your slope angles if and when you notice rollerballs, wet loose avalanches or the snow surface becomes damp and sloppy…
…or when you sink into your waist after stepping out of your skis or board:
Weak layers of faceted snow buried as deep as 5’ sit on some slopes on North facing terrain in the Alpine. This set up will not be found everywhere. Because of this variability, it is especially important to treat this terrain with suspicion. Assessment of this issue is very difficult. The best strategy for “managing” this problem is to avoid this terrain for the time being and give those underlying weak layers ample time to adjust to the large loads (3’+ snow/3”+ H20 over the last week) that have been placed on them. This is a low likelihood/high consequence scenario that requires patience and time.
The last 24 hours has seen the beginning of a slow and gradual exit of a large low pressure system from our area. That system is in fact still circulating around the Gulf of Alaska. Precipitation, winds, and temps have all diminished. Just a trace of snow fell in the morning hours yesterday. Winds have slowed and temps have cooled slightly overnight.
Today expect showery conditions, with occasional clouds and mostly sunny skies as that system continues to weaken and spin slowly around the Gulf. Temperatures at 1,000′ will climb into the mid 30s F. Winds will be calm and just a trace of precipitation will fall. Snow showers could produce greater amounts in some areas.
The extended outlook is showing a continuation of this pattern over the next several days, as we remain under the influence of broad and weak circulation around the Gulf.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||30||trace||.1||72|
|Summit Lake (1400′)||29||0||0||12|
|Alyeska Mid (1700′)||32||trace||0||42|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||26||sensor||is||rimed|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo Forecaster|
|04/10/21||Turnagain||Observation: north sides||lance breeding|
|04/09/21||Turnagain||Observation: Girdwood to Turnagain Road Observations||W Wagner 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|
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.