Forecast: Salt Lake Area Mountains - Utah Avalanche Center

Forecast for the Salt Lake Area Mountains

Issued by Drew Hardesty on
Saturday morning, December 21, 2019

A MODERATE DANGER exists for triggering an avalanche 2-5' deep on steep northwest to east facing slopes of the mid and upper elevations. Avoid steep, thin, rocky terrain. The danger associated with new wind drifts will reach into the MODERATE category by midday to early afternoon.

Wet loose sluffs may also be triggered in warm, wind sheltered terrain and may pile up more deeply in terrain traps.

Low

Moderate

Considerable

High

Extreme

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Special Announcements

Final report for the Dutch Draw avalanche fatality is available HERE. Consider donating to the Matt Tauszik Memorial Fund to help his wife and young son.

Stocking Stuffers: Thanks to the generous support of our Utah ski resorts and Ski Utah, we have discount lift tickets available. All proceeds from these go towards paying for avalanche forecasting and education! Get your tickets here.

Weather and Snow

Solstice warming aloft.

Southwest winds increasing now;

Relief Christmas Eve?

It's a curious thing to say Happy Solstice while reporting current temperatures in the thermal belt of the mid-elevations in the upper 30s. With a broad, open Pacific trough approaching from the west, winds backed to the west and southwest overnight and are blowing 15-20mph with gusts to 30. The most exposed anemometers (to a southwest flow anyway) are spinning 30mph with gusts to 45. We may see gusts to 100mph tomorrow.

Snow surface conditions this morning are a collector's edition of sun and wind crusts with soft settled powder in the wind and sun sheltered terrain.

Our Week in Review - summarizing the significant weather and avalanche events of the past week - can be found here.

Recent Avalanches

No avalanches were reported from the backcountry yesterday, although a snowmobiler found an old large avalanche debris pile in the Snake Creek area of the Wasatch back that looked to be a few days old.

All other avalanches and observations are listed HERE.

Type

Location

Likelihood

Size

Description

Steep, rocky terrain should still be avoided in the mid to upper elevations on northwest to east facing slopes. While the odds of triggering one of these avalanches a week ago were perhaps 75%, now they may be 10%. What odds are acceptable when the stakes are so high? We interviewed Jenna Malone not long ago and she described it as Thinking in Bets (Why Forecasting is Poker and not Chess). Mark gives the state of the snowpack below.

If you choose to ride slopes where this layer exists, stack the odds in your favor by choosing slopes with a clean runout zone free of trees and rocks that would cause trauma if you do trigger an avalanche.

Additional wind-loading on north-facing slopes that have the persistent weak layer will increase the chances of triggering a large avalanche. Look for signs of wind drifted snow and avoid those areas.

Danger Trend: Steady to Increasing

When will this layer go away?

Info about this layer and where it exists

Type

Location

Likelihood

Size

Description

The southwest winds will increasingly scour and erode any available snow and deposit it in the form of scattered and pockety soft and hard wind drifts in the mid and upper elevations. In some areas, these drifts may land on weak snow surfaces formed over the past week and may be surprisingly sensitive. These areas are more likely sun and wind sheltered terrain where the weak snow surfaces are not as susceptible to decay. I wouldn't be surprised to hear that some are triggered at a distance today or tomorrow.

Drifts are often smooth, scalloped, and rounded and are often formed to the lee of terrain features such as ridgelines, sub-ridges, and rocky outcroppings. Soft wind slabs you're "in the snow" with your sled or skis; hard wind slabs you're "on top of the snow". Hard slabs are often trickier because they allow you to get well on to them before the collapse where the wind pillow/teardrop lens shape tapers down.

Cornice drops and ski cutting can be effective techniques in mitigating wind slab avalanches, but they are inherently dangerous and sometimes provide misleading results. A recent paper (with link to a video) on ski cutting by Bruce Jamieson and others can be found HERE. A take-home point - People can be injured and potentially killed while ski cutting.

Danger Trend: Increasing

Additional Information

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