Turnagain Pass

We saw too many avalanches yesterday to record them all here. I have focused on the largest and most significant avalanches that have been observed in the past 24 hours and will link to relevant observations for those who want to dig into the details. (Turnagain road obs, Summit road obs, Magnum, Manitoba)

• Kern – Multiple large avalanches came down onto the railroad tracks during avalanche mitigation work yesterday morning.

Avalanche debris crossing the railroad tracks near Kern Creek after the avalanche mitigation work. Photo 3.25.22

• Pyramid – Large debris piles at the base of E and N face of Pyramid visible during brief clearing yesterday.

Large debris piles at the base of N face of Pyramid, the crown is not visible due to clouds at upper elevations. Photo 3.25.22

• Eddies – Multiple large avalanches in N bowl of Eddies with wide propagation on all features steep enough to avalanche. We also saw several avalanches on the W face of Eddies with one very large avalanche on the lookers lower right side of the W face.

Wide propagating and large avalanches on N bowl of Eddies at 2000-2500′, there were also some smaller avalanches in the steep gullies on the N face. Photo 3.25.22

W face of Eddies with a small crown in the foreground and very large crown along the skyline in the photo which encompassed the entire lookers lower right face of Eddies. Photo 3.25.22

• Magnum – We never got good enough light to get an accurate sense of the size of the avalanche on W face of Magnum, but based on the debris it is possible that a large avalanche propagated across most of the W face with debris running midway into the alder covered runout zone below. (see photo Magnum)
• Lipps – This is the largest avalanche we saw, propagating across the entire W face of Lipps around the corner onto the S face. The avalanche took out the normal skin track and we estimated the width at 1500-2000′ with a crown depth of 3-6′. Unfortunately the light was not great so the photos do not do the avalanche justice. Hopefully we get some decent visibility so someone can get a better photo of the avalanche before the next storm comes in and buries the crown. (additional photo Turnagain road obs)

Part of the crown on W face of Lipps, which came down around the low angle terrain in the middle right of this photo and then back up and around the corner onto the S face. Photo 3.25.22

• Pete’s South – It appears that the entire S face of Pete’s south avalanched, with debris across the face down to 1000-1500′. We could see the crown along the upper ridgeline during a breif clearing but it was already mostly filled in with wind loaded snow. A group travelling up Johnson Pass sent in this photo from the debris at the base of Pete’s South.

Debris from part of the Pete’s S avalanche that ran to the creek bottom and reportedly had large trees within the debris. Photo from Anonymous 3.25.22

The March madness continues with another 1.4″ of SWE at Turnagain Pass which should translate to 12-18″ of new snow in the past 24 hours at upper elevations. Girdwood is showing slightly less SWE at comparable elevation, but the upper elevation weather station at Alyeska is reporting 1.8″ of SWE which should be 15-18″ of new snow at upper elevations. The storm total snowfall estimates at 2,500′ beginning Wednesday to 6am Saturday are:

Girdwood Valley:   40-60″ snow, 4.7″ water equivalent
Turnagain Pass:   40-66″ snow,  5.0″ water equivalent
Summit lake:    15-20″ snow, 1.5″ water equivalent*

*SNOTEL seems to be under reporting, these estimated totals for Summit are based on this observation

All this new snow is accompanied by strong winds at upper elevations with averages of 15-40 mph and gusts up to 70 mph, which are actively transporting snow. Overall, the message is clear; avoid all avalanche terrain and give the snowpack time to adjust to this large new load. That includes runout zones from overhead avalanche paths. Yesterday was the first time I have ever decided not to get out of the car and ski Tincan trees because of the potential for avalanches. I know this terrain seems benign, and 99% of the time it is, but with the amount of new snow we have received and the potential for wide propagation, remote triggering, and avalanches on low angle slopes due to the layers of buried surface hoar there are real hazards in this type of terrain right now. Even small terrain features could produce avalanches large enough to bury a person right now especially if there is any kind of terrain trap below.

The message is simple right now, do not enter avalanche terrain or areas exposed to the runout zone of avalanche terrain. It is not worth the risk of being involved an avalanche of the size we have observed across the forecast area in the past 24 hours. Driving through Turnagain Pass yesterday we saw very large avalanches with wide propagation on relatively low angle terrain in many locations. It is a pretty safe guess that one of the three layers of buried surface hoar currently residing in our snowpack are the culprit for most of these avalanches. The potential for triggering very large avalanches still exists today and due to the persistent nature of these weak layers it will take time for them to adapt to the new snow load before it becomes safe to travel in the mountains again. Unfortunately, it looks like another storm is coming on Sunday afternoon which will create dangerous avalanche conditions again. Please be patient and give the mountains time to settle down before venturing out.

A layer of buried surface hoar in a snowpit from the Summit Lake area. Photo Andy Moderow 3.25.22