Building storm snow, combined with wind today will add a new slab on top of an already loose and weak surface. We can expect tender soft slabs from wind buildup today to travel far and fast, but initially low volume. We have a couple questions to answer while in the backcountry today.
1. How much snow is building from today’s storm?
2. How is the new snow bonding to the old snow?
If the answer is “lots of new snow” and “poor bonding”, then the danger rating will be bumping into CONSIDERABLE by the afternoon today.
Yesterday we saw medium size natural and skier triggered sluffs, with a few small slabs from wind (see picture below from Pete’s South). With new snow expected today, we can expect a similar avalanche character but on a larger scale. Loose snow sluffs are likely, and soft wind slabs 1-2 feet deep are possible by this afternoon.
I was almost ready to drop the discussion about persistent weak layers, then Wendy and Sean found a great example of this problem lingering in Turnagain Pass yesterday. We still consider this problem to be isolated, but the red flags and pit results indicate that those isolated areas may still be triggerable by a person. This problem is from the late January crust that produced a weak layer between 1900 and 3000 feet and has been responsible for a handful of human triggered avalanches. Be aware of this problem at mid-elevations and especially in areas with a thinner snowpack where the weight of a person could collapse the problem weak layer.
Yesterday was sunny, with a little wind up high. The sun from the last 2 days has just barely added a crust to direct south facing aspects, thin enough that it’s not a big issue for skiing quality. Wind had enough force to build and trigger some very shallow slabs in steep terrain.
Today, a blizzard warning is in effect until 4pm. 5-10 inches of snow are predicted for the mountains of Turnagain Arm, with east wind 35-45mph. Temperatures should remain cold enough for snow to sea level. The front responsible for today’s blizzard will pass by this evening, but snow showers remain in the forecast for tonight and the next several days.
Wendy will issue the next advisory tomorrow morning, February 24th.
|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|
|01/12/21||Turnagain||Avalanche: Seattle Ridge/Center Ridge||A Schauer Forecaster|
|01/11/21||Turnagain||Observation: Tincan Trees||Schauer/ Roberts Forecaster|
|01/10/21||Turnagain||Observation: Center Ridge Meadows||Alaska Avalanche School Pro 1 Course Latosuo|
|01/10/21||Turnagain||Avalanche: Tincan trees||Anonymous|
|01/09/21||Turnagain||Observation: Johnson Pass||Anonymous|
|01/08/21||Turnagain||Observation: Sunburst meadow between Hemlocks||Anonymous|
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.