A moisture laden storm is currently moving through the Gulf bringing heavy snowfall to elevations above ~800′ and rain below in the Girdwood Valley and Turnagain Pass zones. Winds have been strong with the snowfall from the East – 30-40mph with gusts in the 70’s mph. Snow totals at the mid-elevations from overnight are:
Girdwood Valley: 8-10+”
Turnagain Pass: 9-11+”
Summit Lake: 2-3″
We are expecting an additional 10-15″ to fall today before the storm slows down tonight. A variety of storm snow avalanches are expected today. These include:
WIND SLABS: With such strong winds associated with the snowfall, much of the avalanche activity is likely to be on wind loaded slopes. These ‘wind slabs’ are expected to be 1-3′ thick and standard storm-induced slabs that are the most unstable during wind loading and directly after, but can stability quickly.
STORM SLABS: In areas sheltered from the wind we may see slabs release from denser storm snow falling over less-dense snow.
LOOSE SNOW: Loose snow avalanches are likely on very steep and rocky terrain.
*In addition to the avalanches expected within the storm snow, there is a possibility that a slide could break into weaker layers that reside 2-3′ deep in the pack. If this is the case, then large avalanches could result. More on this below.
Photo: The approach of the storm. This photo was taken yesterday afternoon by Andy Moderow. A soft, but wind affected, pre-existing surface is now covered with 8-10″ of new snow from overnight with another 10″+ today. The good news is, there are no weak layers on yesterday’s surface and bonding with this new load should occur relatively quickly (in a day or so after the storm).
Around 2-3′ below the snow’s surface sits a layer of weak snow on top of either a hard crust (elevations below 3,000′) or a hard old wind surface (above 3,000′). The weak snow is comprised of facets that are bonding and in some cases surface hoar. In all our pit tests these weak layers are proving to be quite strong and unreactive. However, with a good shock to they system today – around 2″ of water weight rapidly added to the pack – we can’t rule out the potential that these old weak layers may become overloaded and a large avalanche release.
We saw a brief break between storms yesterday as skies broke up and snowfall ceased for the middle part of the day. The Easterly winds, on the other hand, remained strong enough that several folks noted plumes on the peaks during the day.
Overnight, a Pacific storm moved in and has, as of 6am this morning, added up to a foot of new snow at the higher elevations (above the snow stations). See tables below for snowfall and water numbers at the stations. The rain/snow line is hovering right around 800′ currently and expected to remain. Ridgetop winds picked up as well overnight into the 30-40 mph range with gusts in the 70’s. For today, we should see this very stormy weather continue though this evening before the storm starts thinking about moving out.
Tomorrow, we should see instability showers with moderate Easterly ridgetop winds. This means we could see either skies open up a bit or light snow showers. Stay tuned.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||29||9||0.7||55|
|Summit Lake (1400′)||26||2||0.2||19|
|Alyeska Mid (1700′)||31||9||0.66||39|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||N/A||N/A||N/A|
|05/06/20||Turnagain||Avalanche: Pastoral Peak, north face||Andy Duenow|
|04/10/20||Turnagain||Avalanche: Wolverine||Mike Records|
|04/10/20||Turnagain||Observation: Eddies lookers right shoulder||Matt Yoder|
|04/09/20||Turnagain||Observation: Bench Peak||Mike Records|
|04/04/20||Turnagain||Observation: Pete’s North||Anonymous|
|03/26/20||Turnagain||Avalanche: Tincan – Proper (SW facing)||CNFAIC Staff|
|03/26/20||Turnagain||Avalanche: Seattle Ridge||W Wagner Forecaster|
|03/25/20||Turnagain||Avalanche: Sunburst Uptrack @ 2000′||J. Boisvert|
|03/24/20||Turnagain||Observation: 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.