Natural avalanches were again observed yesterday in the advisory area as the second wave of the storm brought another round of strong winds, heavy precipitation and rising temperatures. Rain fell up to approximately 2000′ and saturated the upper layers of the snowpack at lower elevations. In the past 2.5 days Turngagain Pass has received 3 inches of water (SWE) and over 3.5 was recorded in Girdwood. This water weight (either as snow or rain) combined with strong winds overloaded the existing snowpack. Many of the avalanches observed were releasing at the new snow/old snow interface but a few looked to have released farther into the snowpack on the old faceted layers.
It is important to remember that today a variety of avalanche concerns are present and will likely be triggered if you venture into the mountains. Snow is expected to fall today will an additional 5-15″ forecasted as temperatures cool down. Storm slab avalanches at all elevations, wind slabs in leeward terrain, large cornices along ridgelines and wet snow at lower elevations should all be taken into consideration. Natural avalanches are still a possibility today and it’s crucial to understand that human triggered avalanches are likely. Keep slope angles less than 30 degrees and avoid being in avalanche runout zones. Pay close attention to signs of instability: recent avalanches, cracking and collapsing (whumpfing).
Large avalanche on the west face of Pyramid observed yesterday from Tesoro.
Natural avalanches on Seattle Ridge observed from the motorized parking lot yesterday.
Sustained high ENE-SE winds continued to move snow yesterday and obvious cross-loading and scouring was observed. Expect leeward areas to be loaded and sensitive to triggering. Winds are not forecasted to be very strong today but with additional snow in the forecast watch for changing conditions if they do increase and start to move the snow around. Look for cracking and avoid pillowed or drifted areas.
Warm, wet snow and high winds are the perfect cornice building conditions. Steer clear of ridgelines. Cornices may break farther back than expected and poor visibility may make it really hard to judge where they are. If they do fail they could trigger a slab avalanche below.
Wind transporting snow and obvious cross-loading on Seattle Ridge yesterday.
Weak snow (facets and depth hoar) in the lower layers of the snowpack continues to be a concern in our advisory area. Avalanches occurring in the upper layers have the potential to step down and release the entire snowpack in some places. If this does happen the volume will be large and could run long distances. As more and more weight is added to the snowpack this becomes more of a concern. A few of the naturals yesterday looked to have run into older faceted snow. The possibility of these large avalanches is another reason for conservative terrain choices today.
Yesterday was mostly cloudy with a window of clearing in the afternoon. Snow and rain fell throughout most of the day. Rain/snow line was approximately 2000′. Temperatures were in the high 30Fs in the valleys and mid to high 20Fs at upper elevations. ENE-SE winds were gusting up to 100 mph early in the morning. They stayed in the 30s with gusts in the 40-50s for much of the day. Snow and rain showers continued overnight and winds mellowed out early this morning. Temperatures cooled slightly in the last few hours.
Today will be mostly cloudy and another pulse of moisture is expected to bring 5-15″ of snow. Winds are expected to shift to the SW and be 10-20 mph with gusts into the 30s. There is a general cooling trend forecasted throughout the day with cold air moving in from the south (yep sounds odd). From the NWS discussion this morning, “Arctic air has wrapped all the way around from the Bering Sea within the larger scale surface low.” There is another pulse of moisture tonight and a generally unsettled pattern forecasted throughout the week.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||4||1||74|
|Summit Lake (1400′)||35||rain||.2||25|
|Alyeska Mid (1700′)||35||6||1||61|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||26*||SE*||32*||51*|
*Seattle Ridge is recording intermittenly, data from 6am-6am is incomplete.
|11/28/20||Turnagain||Observation: Tincan trees||Bob Lieberman|
|11/28/20||Turnagain||Observation: Tincan Trees||Tully Ward-Hamer|
|11/28/20||Turnagain||Avalanche: Seattle Ridge Flats||W Wagner Forecaster|
|11/28/20||Turnagain||Observation: Tincan Treeline||Eeva Latosuo|
|11/28/20||Turnagain||Observation: Sunny Side||Peter Wadsworth|
|11/27/20||Observation: Sunburst||Andrew Schauer Forecaster|
|11/27/20||Turnagain||Observation: Eddies||Eric Roberts Adam Rothman|
|11/26/20||Observation: Seattle Ridge||Andrew Schauer Forecaster|
|11/26/20||Turnagain||Avalanche: Sunburst||Brooke Edwards / Nick D’Alessio|
|11/26/20||Turnagain||Observation: Tincan Trees||Tony Naciuk|
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.