Avalanche forecast

Salt Lake

Issued Dec 14, 2021valid to Dec 15, 2021Utah Avalanche Center

Avalanche danger

Alpine
Treeline
Below treeline

Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Areas of CONSIDERABLE avalanche danger exist on all steep northwest to east-facing slopes at the mid and upper elevations. This terrain is to be avoided. You can trigger 1'-3' deep avalanches today while on, above, below, or adjacent to steep terrain. Dangerous avalanche conditions exist in the backcountry.

Avalanche problems

Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alpine
Treeline
Below treeline
Likelihood
Likely
Size
2
Most of the avalanches we've seen over the past few days have been soft slab avalanches failing on a persistent weak layer. This interface, now 12-36" down, is a facet or facet/crust combination that will remain problematic and reactive for some time, particularly with new "loading events" (wind or snow). Today's wind will continue to stress this weak layer, and I wouldn't be surprised to hear of new avalanches.

If you're heading to slopes on the northern half of the compass, it will be essential to stick to low-angle terrain with nothing steep above you. Unfortunately, we have a dangerous snowpack right now, and we should not trust it. Avoidance is key. Remember, avalanche terrain is any slope over 30 degrees in steepness.

Danger Trend: Increasing with new snowfall and wind.

Photo: Torrey & Graves showing the weak faceted snow layer in their snowpit and hands.
Wind Slabs
N
NE
E
SE
S
SW
W
NW
Alpine
Treeline
Below treeline
Likelihood
Likely
Size
2
South and southwest winds will and have created sensitive and stubborn wind slabs on many steep slopes, even at the mid-elevations and on mid-slope terrain features. I anticipate drifts to be primarily west to north to easterly aspects, but they may be found around the compass. Drifts are generally round and smooth and sometimes 'scalloped.' Sometimes they sound hollow like a drum. Look for and avoid rounded pillowy-looking snow. Wind drifts may break out well above you.

Note: that any triggered wind slab may step down another 12-36" into older faceted weak layering from October/November, creating a much larger avalanche. Natural avalanches may be possible today.

Recent Activity

Yesterday one avalanche was reported from the Backcountry along the Park City Ridgeline in No Name Bowl. This avalanche was remotely triggered (from a distance) and was roughly 2' deep 400' wide and ran into the flats breaking a few small trees. You can find all backcountry observations HERE.

Special Announcement

Heads Up: this week, we have an active weather pattern with plenty of wind and new snow in the weather forecast. This wind and new snow will overload buried weak layers, creating dangerous avalanche conditions over the next few days (read more below).

Snow and Weather

Currently, the skies are clear, and the upper elevation mountain temperatures are 22-28 °F above about 8,000'. Winds continue to crank across the upper elevation ridgelines blowing from the south with speeds of 25-35 mph, gusting into the 50's and 60's. Yesterday afternoon, Hidden Peak (11,000') recorded a wind gust at 103 mph. Speeds of 96-110 mph define a category two hurricane. Impressive!

Today, we can expect increasing clouds and temperatures climbing into the upper 20's to the low 30's °F at about 8,500' in elevation. As a large-scale storm approaches Northern Utah, the southerly winds will remain strong, with speeds in the 25-35 mph range for much of the day. We could see gusts at the highest elevations hitting the triple digits again.

It's a one-two punch, with the first storm starting this evening around the dinner hour. The southerly winds finally back to the west and slow in speed as the front crosses overhead around 11:00 pm. By Wednesday morning, we could see 10"-15" of new snow (0.80"-1.0" water). A brief break in the action throughout the day on Wednesday will allow the second wave to move in later in the evening, lasting into Friday with another 5"-8" of new snow (0.40"-0.60" water). In total, we could see anywhere from 15"-25" inches of new snow over the next couple of days.

Video: Loop of the 500 millibar height / 500 millibar Vorticity showing both storms impacting Northern Utah with a precip total at the end.

General Announcements

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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.

Observations and Avalanches

Backcountry Emergency Procedures