After a break in storm systems yesterday, we have another strong Pacific storm over us currently. This system is a bit warmer and bringing varying snowfall amounts around the region. The rain/snow line is hovering around 800′ (good news for keeping the snow at Turnagain Pass, which is at 1,000′). It is also a “Girdwood Special” as far as snowfall totals go: Girdwood Valley has picked up 16″ so far, Turnagain Pass 8″ with Summit Lake only seeing 2-3″. Snowfall will continue through the day with an additional 8-14″ expected.
What this all means for avalanche conditions is another HIGH hazard day in the backcountry. If you are considering heading out keep in mind:
1) Natural wind slab avalanches are likely on slopes being loaded by the winds. These will be 1-3′ thick and have the potential to break into older snow.
2) If slides break into older weak layers, we could see very large avalanches, up to 6′ thick (more on this below).
3) In sheltered areas, out of the wind, slabs up to 2′ thick are still possible due to a layer of surface hoar and near surface facets that sat 10-15″ below the surface yesterday. Very careful snowpack assessment is needed if you are in a sheltered zone – in the Tincan Trees for example.
4) Cornices: With such strong winds and warm snow at the high elevations, we can expect cornices to be forming and breaking off. These ‘backcountry bombs’ are likely triggering avalanches below. Even if the winds subside today, these can still break naturally
There are two older weak layers in the pack we are watching. These can be seen in the photo below. Both layers are composed of a mix of surface hoar and near surface facets. These are persistent grains types that can produce large avalanches during, and after, a ‘rapid loading’ event such as today. If today isn’t enough load, then possibly the next storm cycle coming tomorrow through Wednesday. An avalanche breaking this deep in the pack can be very large, connect across terrain features and run to valley bottoms. We are unsure if this could happen today, but it is definitely on our minds.
Overcast skies, light snowfall and moderate to strong winds covered the region yesterday. Only around 1-2″ of snow accumulated with rain falling below ~600′. Ridgetop winds averaged in the 20’s mph from the East with gusts in the 40’s mph.
Overnight, a strong low pressure system moved into the Gulf and is bringing warm air and moisture with it. See the Satellite image below. Sunburst is averaging Northeast winds in the 60’s this morning with a peak gust of 110mph! The rain snow line has crept up to ~800 feet and models are showing it rising to 1200 feet today. Precipitation amounts vary significantly across the region, see the 24-hour charts below. The storm will begin to move out today but strong Easterly ridgetop winds and lingering snowfall (rain below 1200′) will remain. Ridgetop winds are slated to average in the 30-40’s mph with another 8-14″ of snow above treeline and around 1″ of rain at sea level.
Another warm, wet and windy storm is on tap for Tuesday and Wednesday. We are watching the rain/snow line closely and so far it looks to fluctuate between 500 and 1200′ for this one.
Image below is from the NWS: 5am infrared satellite picture of the strong Pacific storm over us today.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||31||8||0.7||68|
|Summit Lake (1400′)||32||2||0.3||19|
|Alyeska Mid (1700′)||31||16||1.35||57|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||N/A||N/A||N/A|
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|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|
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.