With a few inches of snow overnight, plus the addition of 4-8” at treeline today, the upper elevation slopes could see a total of a foot of new snow by this afternoon. There are two main things that will keep this new snow from bonding quickly: (1) The storm will be “upside-down” – due to a rise in temperature with snowfall. This creates a situation where more dense snow is deposited over less dense snow forming a slab/weak layer combo. And (2), there are several slopes that received enough wind over the past few days to create a hard wind crust/slab that will act as a bed surface for this upside-down storm to fall on. A few of these hard surfaces had a couple inches of weak snow on top that will also help to keep the new snow from bonding right away.
In addition to the Storm Snow concerns we also have Wind Slab avalanches. East winds have ramped up overnight and should continue to be in the moderate to strong range on the ridgelines. Even if snow totals do not amount to much there is still plenty of snow available for transport to form 1-2’ deep wind slabs. These will likely be soft and easy to trigger.
Watching for all the obvious signs of instability will be key today. These are:
Shooting cracks, whoomphing and collapsing in the new snow
Below treeline we will likely see wet snow falling on a crust. Watch for any new snow in these areas to have a hard time sticking to the crust as there will be 2” of weak snow sandwiched in between. This weak snow is the few inches that fell on Wednesday which began to facet with the cold temperatures Thurs/Fri. We may not accumulate enough snow at these elevations for it to become a problem but something keep in mind.
With warmer temperatures, the addition of a foot or so of snow (~1” of water equivalent ) and strong wind there is the possibility of adding enough load on certain slopes to wake up a deep slab here or there. This storm does not look big enough to induce a deep slab avalanche cycle similar to last Sunday/Monday, but we can’t forget the possibility remains that one of these larger slides could occur. The 4-8” of well developed faceted snow near the ground from our early season is still weak enough and present in our start zones to warrant concern.
Cloudy skies gave way to light snowfall yesterday as a low pressure system is pushing a warm front over our region currently. We have seen around 3″ of snow overnight on Turnagain Pass, 4″ at Girdwood Valley mid elevations and 2-3″ down at Summit Lake. Temperatures have warmed to the mid-upper 30’s at sea level, where there is currently rain/snow mix, and mid 20’s F on the ridgelines. Winds have increased from the east averaging 35mph overnight and gusting over 60mph on the peaks.
Today we can expect another 4-8 € of snowfall with the rain/snow line creeping up to 800′. The rise in temperature should allow ridgetops to get as warm as the upper 20’s by this evening. The strong east winds look to slowly taper off and blow around 25-30mph with gusts near 50mph through the day.
Tomorrow we should see a break in the precipitation and wind with another shot for Tuesday.
Fitz will issue the next advisory tomorrow morning, January 21st.
|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: 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.