Turnagain Pass Avalanche Forecast
The avalanche danger is CONSIDERABLE above 2500′ today. Lingering wind slabs up to 2′ deep that formed yesterday are likely for a person to trigger at higher elevations and in steeper terrain. Another storm is approaching this afternoon which will bring 6-12″ of snowfall to the forecast area and will increase avalanche danger this evening and overnight. Below 2500′ the avalanche danger is MODERATE. Wind slabs are possible for a person to trigger in exposed terrain. Loose snow avalanches in steeper terrain are likely and could include loose wet avalanches below 1000′.
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
We will have a brief break between storms this morning before the next one arrives around 3 pm today, bringing another 6-12″ of new snow to the area overnight tonight. Slightly higher snowfall totals are expected for Girdwood, Portage, and Placer compared to Turnagain Pass. The heaviest snowfall with this storm will again be in Hatcher Pass, where another 18-24″ of snow is forecast.
We expect that the 4-10″ of new snow from yesterday will bond well to the old surface and slab avalanches in areas sheltered from the wind today are unlikely. The main avalanche problem before the next storm arrives will be wind slabs at higher elevations that were created yesterday, with winds averaging in the teens and gusting up to 40 mph at ridgetops. Wind slabs could be up to 2′ deep and will be likely for a person to trigger at upper elevations. Especially along ridgelines, in cross loaded gullies, and convex terrain features. Watch for shooting cracks, fresh wind drifts, and hollow feeling snow to identify wind loaded terrain features. Testing how reactive wind slabs are on small terrain features is a great way to evaluate the potential size of wind slabs before entering more consequential terrain.
Cornices: Added snowfall and wind will have built cornices a little larger yesterday, so be aware that they could be more reactive to human triggers today.
Loose Snow Avalanches: Dry loose avalanches (sluffs) are also likely at upper elevations in the new snow on steeper terrain features today. At lower elevations, wet loose avalanches are possible as well due to the warm temperatures towards the end of yesterday’s storm.
Expected snowfall totals from the next storm system. Hatcher Pass is still favored by the flow direction of this storm, and we expect slightly higher snowfall in Girdwood, Portage, and Placer compared to Turnagain. Graphic courtesy of NWS Anchorage 2.16.22
In areas of the forecast zone with a shallow overall snowpack we are still dealing with weak layers that were buried in November and continue to be reactive in snow pits and produce both natural and human triggered avalanches. This widespread weak snowpack structure is concerning because of the potential to create large and wide propagating avalanches. For most of our core forecast area the snowpack is deep enough that these weak layers are not a huge concern, but on the margins of our forecast area and other regions that harbor a thin snowpack (e.g. Summit Lake) these layers should be evaluated carefully before entering avalanche terrain. Avalanche mitigation along the Seward Highway near Summit Lake yesterday produced several avalanches, including two with wide propagation and a long runout (see photo) that likely failed on a layer of buried facets from November.
Glide: In the past 10 days or so we have witnessed glide cracks opening up again in Turnagain Pass, most notably on Repeat Offender above the Seattle Ridge uptrack. Glide avalanches are very unpredictable and warrant avoiding spending time in their potential runout zone.
Results of avalanche mitigation work along Seward Highway yesterday. Multiple avalanches appeared to release on older buried weak layers and produce wide propagation. Photo 2.16.22
Example of a thin snowpack from a wind swept area in Turnagain Pass which is harboring a concerning weak layer of facets about 1.5′ deep. Photo Andy Moderow 2.15.22
Yesterday: Snowfall throughout the day mixed with rain near sea level in some locations. Storm totals since 1 am Wednesday were 4-6″ of snow at Center Ridge and 6-10″ at Alyeska mid. Winds were averaging 10-20 mph with gusts up to 40 mph on Sunburst until 5 pm yesterday, then dropped off to single digits overnight. Temperatures cooled slightly overnight but are still hovering around freezing at 2000′.
Today: A brief pause in snowfall during the morning today before another wave starts around 3 pm, with 6-12″ of snowfall expected by Friday morning. Snow line should stay around 500′ during this storm. Winds will increase as the snowfall intensifies with averages of 15-25 mph and gusts into the 40s during the peak of the precipitation around midnight.
Tomorrow: Snowfall should stop early tomorrow morning and winds will switch to west during the day tomorrow at 10-20 mph. Cloud cover should thin on Friday but lingering low clouds could still cause poor visibility. Temperatures will gradually drop throughout the day into the teens at ridgetops and 20s at trailhead elevations for the weekend. Conditions look largely similar for Saturday and Sunday with patchy low clouds, light winds, cool temperatures, and no significant precipitation expected until early next week.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||31||3||0.3||93|
|Summit Lake (1400′)||29||2||0.2||42|
|Alyeska Mid (1700′)||30||4||0.4||NA|
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||25||E||5||20|
|05/22/23||Turnagain||Avalanche: Tincan||Nick D'Alessio|
|05/12/23||Turnagain||Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit||Heather Thamm|
|05/07/23||Turnagain||Observation: Tincan – Bear Tracks||CNFAIC Staff|
|05/05/23||Turnagain||Observation: Seattle Ridge||AS/ WW Forecaster|
|05/02/23||Turnagain||Observation: Cornbiscuit||Schauer/ Sturgess Forecaster|
|05/02/23||Turnagain||Observation: Seward Hwy Turnagain Pass||Joel Curtis|
|04/30/23||Turnagain||Observation: Magnum||Ayla, Kit Crosby, Barton|
|04/29/23||Turnagain||Observation: Tincan||John Sykes|
|04/28/23||Turnagain||Avalanche: Taylor Pass/Pastoral||Schauer/ Creighton Forecaster|
|04/28/23||Turnagain||Avalanche: Tincan||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: email@example.com
|Area||Status||Weather & Riding Conditions|
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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.