Forecast: Salt Lake Area Mountains - Utah Avalanche Center

Forecast for the Salt Lake Area Mountains

Issued by Nikki Champion on
Wednesday morning, January 15, 2020

Today the avalanche danger is CONSIDERABLE on all mid and upper elevation slopes with recent deposits of wind drifted snow. Human triggered avalanches are likely with naturals possible, particularly with cornice failure. Avoid travel on and below steep slopes and in avalanche runout zones.

Some localized terrain also possesses the potential to step down into the older weak layers that have otherwise been dormant for some time now.

A MODERATE danger exists at low elevations where wind drifts can exist on isolated terrain features.

Today, look for signs of wind drifted at all elevations, and avoid those slopes.

Cornices are large and growing. If traveling near a cornice, give them a lot of space both while traveling above them or below them. They can break back farther than expected, and/or trigger an adjacent wind drifted slope.

Low

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Weather and Snow

Since yesterday morning, another 3-7 inches of snow fell in the mountains bringing the snow totals in the upper Cottonwoods close to 100 inches since the New Year. Strong west-southwest winds worked the ridgetops throughout the day with gusts reaching 70 mph at the highest ridgelines before dying down into the evening. Winds are currently northwesterly with gusts in the upper 20s at ridgetops. Temperatures are currently ranging from 1-10 F.

Today, we will get a break in the winds and snow. Winds will switch from northwest this morning to southwest this afternoon, averaging 10-25 mph, with gusts up to 40 mph near 11,000 ft. Skies will be partly cloudy. Temperatures will be in the mid-upper 20s F.

Looking forward, the next system will begin tomorrow evening into early Friday morning. We can expect another 4-8 inches of snow (.5 inches of water) and extremely high winds, hitting speeds near 80 mph at the upper elevations. Stay tuned.

Snow totals since New Year -

Solitude - 85”@4.14 SWE

Brighton - 100.5”@6.28 SWE

Alta - 100”@6.32 SWE

Canyons - roughly 53"@3.45 SWE

Recent Avalanches

Yesterday no new avalanches were reported in the backcountry, but plenty of natural cornice fall was seen. At the ski resorts mitigation work was producing both soft slab and hard slab avalanches of wind drifted snow big enough to bury a person.

Yesterday, I did go look at one of the avalanches from this past weekend on East Reynolds. On Sunday, a skier unintentionally triggered a 2' deep and 50' wide pocket on east Reynolds Peak at 9200' east facing..and escaped off to the side before being caught. We are beginning to get more suspect of the north-facing terrain that previously avalanched, and still has the October/November facets at the ground. While most of the slide path was filled back in, areas within the slide were deeper than the new/old interface suggesting that it stepped down into a deeper faceted layer. You can find my whole observation HERE.

Below you can see the blown-in slide path and crown, with a deeper section circled. Reynolds, East Face, 9200'.

I'd encourage you to look at all the details of the avalanches and observations, found in the Menu bar above.

Type

Location

Likelihood

Size

Description

Even though the winds have finally begun to die down, today wind slabs will continue to be on all aspects of the compass and likely human triggered on steep terrain and could continue to run naturally.

Everywhere I traveled yesterday, every aspect and every elevation, from the trailhead to the ridgeline I was able to find signs of wind drifted snow. While the fresh slabs of wind drifted snow will be concentrated on upper elevation north facing terrain, they will not be isolated to that terrain. The southwest winds worked the entire range, and heavily influenced mid-elevation slopes as well. Expect to find wind slabs at all mid and upper elevation slopes, and even steep wind loaded terrain features at low elevations.

The other tricky thing about this wind drifted snow is the varying sensitivity it could possess. Winds were howling yesterday, and with more snow available for transport we could have a soft slab, hard slab, soft slab sandwich on our hands. I would expect to see extremely soft slabs, easily triggered remotely from a distance in some areas and/or extremely firm, and stubborn hard slabs that are more difficult to trigger in others.

Today look for slopes with any signs of wind drifted snow, such as cracking, hollow sounds, and pillow-shaped snow, and avoiding those slopes.

A photo Greg took yesterday on 10420 in Big Cottonwood Canyon of a fresh dense wind drift sitting atop the lower density snow.

The CORNICES are getting huge, and just continue to grow. Yesterday while I was out I saw signs of growing cornices and signs of natural cornice release. These cornices are likely to continue releasing and could trigger adjacent wind slabs on steep slopes below. If traveling near a cornice, give them a wide berth as they will break back farther than expected if traveling above them and could naturally trigger an avalanche above you if traveling below them.

A photo of the large growing cornices from the Reynolds Ridgeline yesterday where they continue to release naturally.

Type

Location

Likelihood

Size

Description

We have two persistent weak layer issues, that are collectively impacting the entire compass:

Southeast through Southwest: We have a poor snowpack structure that includes a layer of weak facets adjacent to a crust on the mid and upper elevations. This layer could now be anywhere between 2-5' deep in the snowpack. While we haven’t seen any recent activity from this layer, as we continue to add more load in the form of wind and snow I am not ready to write it off yet.

West, North, and East: We haven’t talked about the October/November facets in a while, and overall considered them dormant, but as we continue to add increased load areas that have previously had avalanches, known as repeater slopes, this season will become increasingly suspect. Yesterday I went out to an avalanche on East Reynolds, a common repeater slope, to investigate the layer which the avalanche failed on. Most of the slide path was blown back in from the recent wind and cornice fall, but we were able to find select areas that were deeper than the new snow/old snow interface. While I cannot confirm that this was the November/October facets, it is obvious that part of that avalanche did step down into a deeper layer of facets.

The Cottonwoods have gotten a ton of new snow, nearly 100” inches in combination with strong winds. These two things together put a lot of stress on the snowpack and if these early season facets were to begin to fail again, now would be the time. Steep, northerly-facing, thin and rocky areas are going to be especially suspect to steep down into a deeper layer and I would continue to investigate repeater slopes.

Bottom Line: With either persistent weak problem, it could be possible to trigger an avalanche 1-3' deep on nearly all aspects at the mid and upper elevations. For this reason, I would avoid terrain steeper than 30 degrees, stick to low angle terrain with nothing steep above or adjacent to you.

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This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.

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