A perfect recipe for dangerous avalanche conditions exist in the 2,000 – 3,000’ elevation band where a uniform weak layer of faceted snow lies in wait 6” to 3+’ below the surface. Level 2 avalanche course students were experiencing large collapses (whumphing up to 100’ radius) on this faceted layer yesterday, proving there is a significant amount of energy within the weak layer. This translates to good potential for an avalanche to propagate across a slope if initiated.
Yesterday’s storm has increased the load overlying this weak layer with wet snow falling above 2,000’ (and rain below). Human triggered avalanches are likely on slopes steeper than 35 degrees. This most recent load may just be enough to initiate a natural avalanche cycle as well, though visibility yesterday was hampered to the point where no natural avalanches were observed.
If you travel in the backcountry today, it’ll be imperative to stick to mellow terrain and avoid steeper connected slopes or runout zones. If you are in a runout zone or on a mellow slope connected to a slope greater than 35 degrees, you’re in avalanche terrain. Remember, you cannot necessarily manage the weather or the snowpack right now but you can always manage your terrain choices to ensure a safe day in the backcountry.
Moderate Easterly winds combined with new snow in the upper elevation start zones have been, and will continue to actively build fresh wind slabs 12 – 24” today on leeward slopes. These could be a problem in and of themselves but also have the potential to step down into deeper weak layers, possibly creating large avalanches.
Below 2,000’ what snow that is on the ground has been well adjusted to the recent rain and warm temperatures. The greatest hazards at these lower elevations come in the form of avalanches initiating in the mid to upper elevations and debris travelling in funneled terrain well below our rain/ snow line.
Moreover as bizarre as it is to say in late-February, early season conditions do exist. Thin snowpack, icy approaches and water crossings are all real hazards right now in the lower elevations.
Yesterday was marked by another warm, wet North Pacific low pressure system that brought steady rain to southcentral Alaska below about 2,000′. Ridgetop temperatures were in the high 20’s with sustained winds in the 20-35mph range from the NE. Girdwood appears to be the precip winner with 1.16″ of water in the past 24 hours as temperatures remained in the high 30’s at sea level throughout the day.
More warm air is on tap across our region though rainfall looks to be more intermittent today than yesterday. Expect temperatures to be in the upper 30’s at 1,000′ with up to a quarter inch of water forecasted. The rain/ snow line again will be somewhere in the 2000 – 2200′ range today with ridgetop winds out of the east in the 15 – 30mph range.
On Monday the weather models hint at (relatively) colder air moving in from the west coupled with continued moist flow though precip amounts are quite nominal at this point.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||35||0||.3||42|
|Summit Lake (1400′)||35||0||.3||7|
|Alyeska Mid (1700′)||35||1/ rain||1.16||25|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||29||n/a||23||58|
|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|
|04/10/21||Turnagain||Observation: north sides||lance breeding|
|04/09/21||Turnagain||Observation: Girdwood to Turnagain Road Observations||W Wagner Forecaster|
|04/05/21||Turnagain||Avalanche: Resort bowl Seattle creek head wall||Clint Kyffin|
|04/04/21||Turnagain||Observation: Center Ridge||Andy Moderow|
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.