A short burst of snowfall yesterday morning added a welcome 5-9″ of very low density snow in the Girdwood Valley and 1-4″ at Turnagain Pass. With the chance for a few more inches of light snow today, this will add to the soft surface conditions, but the avalanche concerns will remain deeper in the pack.
The primary concern continues to be a slab (1 – 3+’ deep) sitting on a layer of intact buried surface hoar. Last week this combination (slab + weak layer) was very touchy causing several large human triggered avalanches including a full burial in Turnagain Pass. As this layer has had time to adjust we have noticed it gaining strength and getting harder to trigger in our test pits. Check out this VIDEO from yesterday. Unfortunately, when it does collapse there is a lot of potential to propagate over an entire slope. In other words, the probability of triggering a large avalanche is decreasing, but due to its thickness and potential to propagate, the consequences are high.
In the right type of terrain you might trigger an avalanche or you might not. Many people could ski the same steep slope before someone hits the right trigger spot. It can be nearly impossible to know the exact location of these areas, but a good rule of thumb is to avoid thin snowpack areas, steep convex rollovers and areas near rocks. If you find yourself creeping into steeper terrain be aware of the consequences below you. It can be easy to assume that just because a slope has been skied it is deemed “safe.”
There is a lot of uncertainty around this avalanche problem. We haven’t received any reports of recent avalanche activity in the last few days. Our observations have been limited to our roadside access on low consequence terrain of Tincan, Sunburst, and Seattle Ridge. We have only been able to investigate this slab plus weak layer combination on slopes below 35° in Turnagain Pass. We don’t know how reactive this weak layer is south of Sunburst or in elevations higher than 3400’. Girdwood received the highest amount of precipitation from the Dec.14-17th storm and this slab layer gets gradually thinner as you head south through Turnagain Arm. We know that the Summit Lake area has the shallowest snowpack, and we suspect it could be easier to trigger a persistent slab in this region.
Yesterday morning Turnagain Pass received 1-4 € of low-density snow and 5-9 € fell in the Girdwood Valley. Winds were light from the East with temperatures in the mid to high 20’s F.
Overnight there has been no new precipitation recorded. Winds were calm and temperatures have increased to 32 °F at sea level and the mid 20’s F on the ridgetops.
There is a chance we could see up to 4-6 € of low density snow at higher elevations today with very light and variable wind. This may be in the form of rain at sea level as temps are supposed to stay in low 30’s F.
Over the next few days, showery conditions are expected in the Western Prince William Sound area and could bring short bursts of snow to Girdwood and Turnagain Arm. Unfortunately, the forecast has a lot uncertainty and these small bands of moisture could miss us. Temperatures are expected to remain in the high 20’s F to low 30’s F at 1,000′ with light and variable ridgetop winds.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||30||2||0.1||28|
|Summit Lake (1400′)||28||0||0||4|
|Alyeska Mid (1700′)||31||4||0.43||21|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||27||]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: email@example.com
|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.