Turnagain Pass Avalanche Forecast
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The avalanche danger is CONSIDERABLE for all elevations. After a week of snow resulting in 6-10′ at mid and upper elevations, a rain/snow mix below 1100′ and sustained ridgetop winds, the mountains need time to adjust to the load. Today large, human triggered storm slab avalanches are likely on slopes over 30° and natural avalanches are possible. Cautious route-finding and conservative decision-making are essential. Give cornices a wide berth and look for signs of instability.
Snug Harbor/Lost Lake/ Seward: These areas are out of our forecast zone but have also received large amounts of snow and caution is advised.
Forecaster chat #3– Saturday, Jan 16. Join CNFAIC forecasters Andrew Schauer and Wendy Wagner, along with special guest Karl Birkeland from the National Avalanche Center, as we talk about how we put together a forecast, and how we put an advisory to use while we are in the mountains.
With a break in the precipitation yesterday afternoon, there was an opportunity to see some of the avalanche activity from the storm. Evidence of large natural avalanches was observed across the forecast zone. A few notable slides listed below:
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 finally have a quick break in the onslaught of heavy precipitation before the next storm starts early tomorrow morning. There is SO much new snow (6-10′) which is incredibly appealing but still potentially very dangerous. It’s a day to carefully evaluate terrain and consequences if a large avalanche does release. Low angle slopes without steep slopes above are great ways to enjoy the new snow without worry. As the snow settles it may become easier to travel but may also mean the slab is becoming more consolidated and may still be sensitive to human triggers. The old snow surface before all the snow fell had a thin layer of weak snow. In addition, there were a few temperature fluctuations throughout the storm cycle that could have also created weak interfaces. There have been large natural and explosive triggered avalanches during the storm with crowns ranging from 2-15′ deep. These are not the type of avalanches you want to mess with. We are hopeful that the new snow will eventually bond well and that we can enjoy it. However, we need more data after the storm and the snowpack needs more time to stabilize. As said many times before the snowpack is guilty until proven innocent and it is still likely that a person could trigger an unsurvivable avalanche today. We are in the 48 hour window after a storm where this is most common.
Signs of instability to watch for today:
– Recent avalanches
– Whumpfing (collapsing) of the snowpack, sure sign to avoid avalanche terrain period.
– Shooting cracks, likely to be seen near ridgelines and on slopes where the wind has formed wind slabs.
Avoid travel on or under cornices as they may be quite tender today and often break farther back than expected.
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 |
There is another tricky element to this avalanche puzzle. We have been tracking a layer of faceted snow associated with the 12/1 rain crust, which is now buried around 8’ deep, and exists at elevations up to around 2500’. We are not sure if any of the large natural avalanches released at this layer. The majority seemed to be storm snow only but the 10′ crown on lower Twin Peaks is suspect. This end of the Pass gets less snow and a lower elevation crown fits into the elevation band where we have found this crust facet/combo. It is unlikely a person could trigger an avalanche on this weak layer at the depths it is buried in Turnagain Pass. However, as we head south towards Summit Lake the storm totals taper dramatically and this could be possible. This is another unknown that needs more data after this storm cycle.
Yesterday: Skies were mostly cloudy in the morning with snow showers and became partly cloudy in the afternoon. Winds were easterly 5-15 mph with gusts into the 20s. Temperatures were in the mid 30°s at sea level and high teens to low 20°Fs at ridgetops during the day and overnight. Skies became mostly cloudy again overnight and easterly winds increased t0 10-20 mph with gusts into the 30s.
Today: Mostly cloudy skies with snow showers, potentially becoming partly cloudy again in the afternoon. Easterly winds 10-20 mph with gusts into the 30s and 40s decreasing in the afternoon. Temperatures in the 30°Fs at sea level and mid t0 high 20°Fs at ridgetops. Overnight snow showers with easterly winds 5-15 mph increasing early Thursday morning. Temperatures in the mid 30°Fs at sea level and mid 20°Fs at ridgetops.
Tomorrow: There is Winter Storm Watch from Thursday morning through Thursday afternoon for Portage Valley and Turnagain Pass. Blizzard conditions possible. Total snow accumulations of 6-10″possible with up to 15″ through the Pass. East winds 15-25 mph with gusts into the 40s. Temperatures in the high to mid 30°Fs at sea level and the mid 20°Fs at ridgetops.
PRECIPITATION 24-hour data (6am – 6am)
Temp Avg (F) | Snow (in) | Water (in) | Snow Depth (in) | |
---|---|---|---|---|
Center Ridge (1880′) | 29 | 3 | 0.4 | 129 |
Summit Lake (1400′) | 25 | 1 | 0.2 | 24 |
Alyeska Mid (1700′) | 29 | 3 | 0.4 | 119 |
RIDGETOP 24-hour data (6am – 6am)
Temp Avg (F) | Wind Dir | Wind Avg (mph) | Wind Gust (mph) | |
---|---|---|---|---|
Sunburst (3812′) | 20 | NE | 13 | 39 |
Seattle Ridge (2400′) | 25 | N/A* | N/A* | N/A* |
*Seattle Ridge anemometer is rimed over.
Date | Region | Location | Observer |
---|---|---|---|
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: mailroom_r10_chugach@fs.fed.us
Area | Status | Weather & Riding Conditions |
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Glacier District |
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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.