Good morning. This is Kevin Wright with the Chugach National Forest Avalanche Information Center on Friday, March 16th at 7am. This will serve as 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).
Timing is everything after a big storm event. Steeper South aspects should be avoided today, where the buried sun crust is creating a problem weak layer. Slopes that are more sheltered from the sun will have less avalanche potential, but the storm snow is still settling and bonding after the recent heavy snowfall. Most areas will have a MODERATE avalanche danger, meaning natural avalanches are unlikely but human triggered avalanches are still possible.
Our most recent storm ended a little over 24 hours ago. Yesterday, the Seward Highway avalanche program was busy reducing the hazard along the highway corridor. They got quite a few significant results, triggering large avalanches that slid down to the road level. Check out a video from that work here. This is really good information that is relevant to the backcountry snowpack situation.
Most of the avalanche activity (natural and human triggered) from that storm was on sun affected aspects. We believe that the melt-freeze sun crust from last week was one of the biggest factors contributing to those avalanches. If the sun comes out today, you will be able to see old avalanche crowns and debris on East, South, and West facing slopes. This is significant because the sun crust and associated facet growth is one of our first persistent weak layers of the season.
On Thursday we were seeing very touchy remote triggering on the sun crust during the storm. Yesterday, the sun crust showed only limited reaction in pit tests, but it still displayed a collapsing character. This problem seems to be getting more stable over time, but we can still expect sunny aspects (with the recently buried crust) to be the most likely places to find avalanche problems today.
That last storm dumped quite a bit of snow in the mountains. Breaking trail was quite difficult yesterday in the deep snow. The sheer volume of snow will create CNFAIC Staff avalanche problems on all aspects including – loose sluffing, wind slabs, and unstable cornices. Less than 24 hours ago there were large avalanches being triggered in our region. AnCNFAIC Staff 24 hours of waiting before traveling onto bigger and steeper terrain will increase your odds of staying safe.
The storm that ended Thursday morning dropped 2-3 feet of new snow across Turnagain Pass and Girdwood. Since that time, the weather has calmed down. Partly sunny skies were the norm yesterday with warmer temperatures and light wind.
Today, the weather is expected to be minor. No snow is forecasted under partly cloudy skies with only light and variable wind. Temperatures may reach into the high 20s in the mountains.
CNFAIC Weather Page and the NWS forecast
I will issue the next advisory Saturday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.