|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|
And the avalanches keep coming… After two weeks of wet, windy and rainy weather, the snowpack below 3,000′ continues to saturate into mush and slide off the mountains; in some cases taking the season’s snowpack with it. If you didn’t know it was still March, you’d think it was late April out there. Another batch of fresh wet slab avalanches were seen yesterday at Turnagain Pass and in Girdwood. These were on Sunburst, Magnum, Cornbiscuit and Seattle Ridge as well as Orca and Maxes in Girdwood. With rain falling as high as 3,000′, we are seeing wet slabs break anywhere between 2,000′ and 3,500′. We are undergoing an impressive avalanche cycle and if you’re itching to get outside, come down to the motorized lot today at Turnagain for our meet and greet and watch the avalanche extravaganza from a safe distance!
To put things in perspective quickly, over the past two weeks there has been upwards of 16″ of rain in the Girdwood Valley and 10″ at Turnagain Pass. As we know, the snow line has fluctuated from 1,000′ to 3,000′ during this time, yet is getting warmer and warming with each storm. This morning temperatures are some of the highest we have seen with 4,000′ peaks bumping up to 30F. This is quite a shock to the snowpack. Remember, wet slab avalanches are unpredictable and unsurvivable if someone was to get caught. The message remains – stay well away from any avalanche terrain including runout zones! There is a change is on the horizon however, clearing skies are expected Monday and Tuesday. What the sun and heat will do to the snowpack will be the next question.
Large wet slab on North facing Sunburst, seen from the Center Ridge parking lot. Released overnight on 3/21 or yesterday morning 3/22. This slab released very near the ground – a closer up image can be found HERE.
West face of Magnum released again sometime late Thursday night, 3/21. The crown is barely visible and debris ran over old debris from last week.
Wet slab on the lower North aspect of Cornbiscuit. Released overnight on 3/21. Another example of how unpredictable the mountains are during this wet weather.
Crown on Orca Mtn, at the head of Girdwood Valley, runs full width. Released overnight on 3/21. Debirs ran full path and into the trees. Image taken from the Tesoro.
What about the upper elevations? Yes, it has been snowing at the higher elevations, yet one must brave the gauntlet of the mid elevations to get there and then hope there is enough visibility to navigate the terrain safely. Although we have little high elevation data since the onset of this two week storm series, we know roughly 1-2′ of new snow has fallen over the past 24-hours with strong easterly winds and therefore can expect the classic storm snow avalanche problems (wind slabs, sluffs and storm slabs) along with cornice falls. Furthermore, Turnagain is looking at 10+ feet of settled storm snow since March 8th and avalanches breaking this deep (on the early March high-pressure surface) are possible – which is a very large avalanche.
South of Turnagain in the Summit Lake and areas in the interior Kenai Peninsula have a very thin snowpack compared to Turnagain. A variety of old weak layers (facets and buried surface hoar) sit in the mid and base of the pack, which have been reactivated by the current warm temperatures and rain. Over the past few days numerous large wet slab and dry slab avalanches have released. These types of avalanches remain possible until a solid re-freeze occurs.
Yesterday: Cloudy skies with light to heavy rain falling up to 2,000′ was seen yesterday. Girdwood Valley weather stations reported 2″ of rain below 2,000′ in the past 24-hours (estimated 1-2 feet of wet snow above). Turnagain Pass stations reported 1-1.5″ of rain below 2,000′ (5-12″ wet snow above). Ridgetop winds have remained Easterly in the 20-40mph range with gusts into the 60’s mph. Overnight temperatures have climbed even further into the low 40’sF at 1,000′ and 34F at 2,500′. WARM!
Today: Cloudy skies with light rain falling up to 2,500′ as the brunt of yesterday’s storm moves out. Roughly .4 – .7″ of rain should fall by tonight, with 3-6″ of wet snow above 2,500′. Ridgetop winds will remain in the 25-35mph range with stronger gusts from an Easterly direction. Warm air will continue to seep into the region pushing temperatures at 3,000′ to 32F and to near 50F at sea level.
Tomorrow: Light rain and snow showers are expected to continue tomorrow as this last system slowly moves out. Cooler air filtering in should drop snow lines to 1,500′ or so and ridgetop winds are forecast to be Easterly, 15-30mph. Finally a break in precipitation and cloud cover is slated for Monday and Tuesday as a ridge of high pressure builds in.
*Seattle Ridge weather station anemometer has been experiencing some issues and may be under reporting wind data.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||36||rain||1 – 1.5||76|
|Summit Lake (1400′)||37||rain||0.2||26|
|Alyeska Mid (1700′)||35||rain||1.7||69|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||32||SE||13*||32*|
|05/06/20||Turnagain||Avalanche: Pastoral Peak, north face||Andy Duenow|
|04/10/20||Turnagain||Avalanche: Wolverine||Mike Records|
|04/10/20||Turnagain||Observation: Eddies lookers right shoulder||Matt Yoder|
|04/09/20||Turnagain||Observation: Bench Peak||Mike Records|
|04/04/20||Turnagain||Observation: Pete’s North||Anonymous|
|03/26/20||Turnagain||Avalanche: Tincan – Proper (SW facing)||CNFAIC Staff|
|03/26/20||Turnagain||Avalanche: Seattle Ridge||W Wagner Forecaster|
|03/25/20||Turnagain||Avalanche: Sunburst Uptrack @ 2000′||J. Boisvert|
|03/24/20||Turnagain||Observation: Turnagain – Road Observations||W Wagner 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.