Turnagain Pass

The last known avalanche activity was associated with the warm storm Saturday night that brought 8-12″ of new snow across the region. Widespread storm snow avalanches were seen once the skies cleared on Monday from Girdwood, Turnagain Pass, to Seward.

After light snow fell during the daylight hours yesterday (5 hours and 34 minutes worth of daylight), snowfall rates picked up overnight. Highest amounts were seen in the upper elevations of Girdwood Valley, Portage/Placer, and Seward. Ridgetop winds were easterly with the snowfall, 10-20mph with gusts near 40, but the good news is, those winds died off overnight as most of the snow fell. That said, today will be day to suss out how much new snow is in the area you are traveling and did it get hit by any winds. The primary avalanche issues will be related to those new snow amounts. Here are some snowfall totals-

Snowfall totals from yesterday (estimated at mid elevations):
Girdwood Valley: 8-12″
Turnagain Pass:  4-6″
Summit Lake:  4-6″
Lost Lake/Seward:  8-12″

New Snow Avalanches:  These could be storm slabs, wind slabs, and dry loose snow sluffs. All of them could be found today, especially in areas that saw 10″ or more of new snow such as in Girdwood and Placer Valleys. Storm slabs will be the depth of the new snow (ish) and found in areas that did not see any wind effect. Wind slabs could be up to 2′ deep along ridgelines where any wind did occur. As always, keep a close eye out for Red Flags – Recent Avalanche, Cracking in the snow around you, and whumpfing sounds/collapsing of the snowpack. The good news is, all these new snow avalanche types should be on the smaller side and easy to identify if we are paying attention.

In areas with only 4-6″ of new snow, avalanches in the new snow will be less of a concern except for wind slabs that may have formed in the higher terrain.

Conditions yesterday on Tincan at Turnagain Pass. Light snowfall, temps in 20’sF, and low light/short days. Photo from Hamer/ Asher 12/19/23.

Last night’s snow was not quite enough to put much added weight on the snowpack and the buried weak layer we keep talking about. This is the faceted snow that is forming near the Thanksgiving Crust, now buried around 3-5′ deep. We’ve been tracking this layer for almost a month and so far the layer has been unreactive. There have been two known avalanches failing on this layer since the crust was buried, around a week ago.

This issue is notoriously difficult to deal with. The short story is we don’t want anyone to be caught off guard; even though the snowpack can seem bomber under the new snow, it may not be. The likelihood of triggering an avalanche on this layer is low, but if you were to trigger something it could be very large. All slopes above 1000′ should be considered suspect, since we’ve seen the same suspicious structure in virtually every snowpit that has been dug over the past two weeks.

Snowpack at the lower elevations of Turnagain Pass. Snow pit tests here showed the weak snow was sandwiched in between the Thanksgiving Crust but was not failing in tests (meaning a strong pack unlikely for a person to trigger a big avalanche here). 12/17/23.