Several days ago we received a snow event that distributed an uneven amount of snow over Turnagain Pass. On the Southern end of Turnagain slab depths average 6” with pockets as thick as 10” in wind deposited areas. On the Northern side of the pass, average slab depths are 10” with pockets 15+” in places. This new snow was also accompanied by sustained East winds (20-30’s mph) causing the slab to become denser and more cohesive in areas along ridgetops. This uneven slab distribution is sitting on a widespread unstable weak layer of facets.
We are on the scarier side of the MODERATE scale for the heart of our forecast zone. There’s not quite enough new snow in most of Turnagain Pass bump the entire area to CONSIDERABLE, but it could be challenging to know exactly where this line exists. In places where slab depths are shallower like Tincan and Sunburst isolated avalanches up to 10″ thick are possible in steep terrain. In places like Eddies and along the Northern end of Seattle Ridge where thicker slabs exist it will be more likely to propagate an entire slope.
In Girdwood the problem is a little harder to evaluate with 6” of new snow covering an older windslab (4-8” thick) which also sits on top of old weak faceted snow.
Yesterday avalanche activity was observed along the Northern side of Seattle Ridge. Forecasters triggered a remote avalanche from 300′ away near the Seattle Ridge weather station. A larger natural avalanche was also observed in this area. There was also a few reports of natural activity near the Girdwood Valley and near Seward.
This avalanche occured on a Southern aspect near Main Bowl on Seattle Ridge and was not witnessed. It is likely to have been triggered naturally yesterday.
This avalanche was triggered remotely from 300′ away on Seattle Ridge near the Seattle Ridge Weather Station.
Collapsing sounds will be your first red flag warning sign. If you hear “woomphing” sounds this is a sign that your weight is enough to collapse the weak layer below the slab and reinforces your decision stay off of slopes greater than 35°.
Remote triggered avalanches are a concern for today and it is extra important to be aware of other groups within the same area. If you are traveling along a ridgeline you could remotely trigger an avalanche on an adjacent slope without even realizing it. If you find yourself along a valley floor avoid the run-out zone of large steep slope. Sunburst ridge and Taylor Pass are a good example of places to avoid today.
Careful snowpack evaluation is recomended today. Click HERE for a demonstration on how to perform a hand sheer test to help you understand our current persistent slab problem.
Warmer temps and solar radiation have caused point releases and roller balls on Southern aspects over the last two days. In summit lake yesterday a 6” slab was triggered on Southern aspect during the heat of the day when temperatures were in the mid 30’sF in this area. It is likely that these aspects are developing a crust layer, but if the sun appears today and temperatures creep into the Mid 30’s again, be aware of wet (damp) avalanches on South facing slopes.
Yesterday temperatures reached into the mid 30’s F below 1500′ with light rain in the morning then clearing off in the afternoon. Only a trace of new snow fell above 1500′. The sun came out in the afternoon keeping temperatures warm, with the hottest part of the day around 2pm. Ridgetop temps climbed into the high 20’sF. After sunset skies remained mostly clear and temperatures dropped into the mid 20’sF. Winds were mostly from the East and averaged 5-15mph along ridgetops.
Overnight temperatures stayed in the mid to high 20’sF and a mostly East wind has been light (5-10mph.) No new precipitation was recorded.
Partly sunny skies are anticipated today with a chance of light precipitation in the evening. Temperatures are expected to be in the low to mid 30’sF at sea level and at higher elevations. Winds from the East may pick up into the 20’s along ridgetops.
Right now it looks like our next best chance for snow accumulation will be on Sunday.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||31||1||0.1||36|
|Summit Lake (1400′)||28||0||0||9|
|Alyeska Mid (1700′)||31||0||0.1||24|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||28||Var.||9||25|
|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.