Yesterday afternoon only a trace of new snow fell, but blowing snow was observed most of the day and weather stations in Turnagain Pass reported moderate Easterly winds 15-30mph during most of the day light hours. This was in addition to moderate Easterly winds that coincided with about 10-12” of new snow the day before. Yesterday’s winds were from the SE on Seattle Ridge and NE at Sunburst, which may have caused slightly different loading patterns on each side of the road. In general Western aspects will be more loaded, but cross loading will range from NW to SW slopes where triggering a wind slab 1-2’ thick will be possible today on slopes steeper than 35 degrees. Several inches of low density snow has fallen overnight without much wind and this may make it challenging to see wind loading patterns. As you travel today be on the look out for obvious signs like shooting cracks and be aware of terrain that may have high consiquences. These slabs are likely to be soft and could be lower on slopes where cross loading may have occurred.
Red Flags to look for:
***Loose snow sluffs are also possible on the steeper slopes and these could run further than expected.
Northern aspects remain suspect of deeper instabilities where 1-2’ of new snow is sitting on a shallow snowpack with poor structure. Yesterday an observations confirmed evidence of two natural avalanches (occurring some time between 1/13-1/14) on the North facing slopes of Sunburst. Several snow pits on adjacent NW slopes revealed poor structure with some propagation potential in deeper layers of the snowpack. This structure is more common on the Southern end of Turnagain Pass (Magnum to Johnson Pass) where a much shallower snowpack exists. It will be in these areas where triggering a slab in a deeper layer of the snowpack may be easier and possible on any aspect.
In the lower elevations below 2000’ buried surface hoar is sitting below 8-12” of new snow. Multiple observers yesterday found this layer on Tincan and Eddies. The Alaska Avalanche School found evidence of two small soft slab avalanches on Tincan, possibly remote triggered mid-storm two days ago. These were small, only a foot deep and 20’ wide, but were also on small terrain features. In the lower elevations it may be possible to trigger a soft slab on steep unsupported terrain features or along gully’s. This could be more of a concern below treeline in places like Portage or Placer Valley, where ice climbers and hikers should be aware of the terrain above and avoid being in the run-out of large steep slopes.
A North aspect adjacent to one of two crowns found on the North side of Sunburst. Tests results were mixed, but found propagation potential in a uniform layer of facets sitting between two wind slabs 16″ below the surface.
Two small soft slabs at 1400′ on Tincan that likely released on 1/14 near the end of the storm. Observers dug pits near by and found buried surface hoar to be the weak layer. Prior to this storm buried surface hoar was found below 1500′ in many places throughout Turnagain Pass.
Yes, we are still concerned about glide cracks releasing. Most of the cracks we know about are in areas rarely traveled. The exception is in -1 Bowl (Main Bowl) in the Seattle Creek drainage where glide cracks threaten terrain commonly traveled. Keep an eye out for cracks, which can be difficult with new snow, and limit time underneath them.
Yesterday skies were overcast becoming obscured by mid afternoon. NE ridge top winds averaged 15 with gusts in the 30’s mph mid-day becoming light from the NW by the evening. Temperatures averaged around 15F cooling to 10F by late evening. Yesterday afternoon to this morning 3-4 € of new snow was recorded at Center Ridge and at the mid way station at Alyeska. Other areas of the Pass only received a trace total overnight.
Today an additional 1-3 inches of snow could fall by late morning with scattered snow showers in the afternoon. Winds will remain light from the NW and temperatures will be around 10F dropping near 0F by this evening.
Cold arctic air over mainland Alaska is expected to bring subzero temperatures to Southcentral, Alaska through the remainder of the week. Skies will be clear with a light Northwest winds.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||14||4||.3||45|
|Summit Lake (1400′)||9||1||.2||15|
|Alyeska Mid (1700′)||12||5||.35||43|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||9||SE||12||46|
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|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|
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.