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Forecast for the Salt Lake Area Mountains

Nikki Champion
Issued by Nikki Champion on
Wednesday morning, December 20, 2023
Overall, the avalanche danger is generally LOW and normal caution exists. You may encounter isolated pockets of fresh wind-drifted snow in exposed terrain at the mid and upper elevations. Wet-loose avalanches should remain on your radar in damp or punchy, unsupportable areas that received rain yesterday and another poor refreeze.
Continue to maintain safe travel habits; this means exposing one person at a time to avalanche terrain, having someone watch them from a safe location, and not traveling above or below other parties.
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Weather and Snow
This morning, skies are broken, and temperatures are in the upper 20s and low 30s F. Winds are from the southwest - gusting in the teens and 20s along mid-elevation ridges with gusts in the upper 30s and low 40s along the highest peaks. Since yesterday, the mountains picked up about 1-2.5" of new snow that began as rain in many places.
Today will remain mostly cloudy with a chance for light snow, temperatures will rise into the mid and upper 30s F, and the southwesterly winds will remain moderate, gusting in the 30s at mid-elevations and mid-40s mph along the highest peaks.
The cold front for Saturday is still on track, bringing moderate to heavy snow from Saturday morning into Sunday. There’s some uncertainty about how long the snow will last on Saturday, depending on how things come together. We expect about 0.5-1 inch of water and 7-14 inches of snow.
Before yesterday, the days of cold and clear weather weakened had the snow surface, with either surface hoar or near-surface facets within the top couple of inches. The dash of new snow yesterday and today may offer a bit of a refresh to areas that may not have been as well protected but will likely not bond well to the weak faceted snow on northerlies or the suncrust on solar aspects. While yesterday’s and today’s trace amounts of new snow are not much of a concern, once larger storms return (and they will), we will likely enter a period of dangerous avalanche conditions.
Recent Avalanches
Yesterday, there was one report of a skier-triggered shallow soft slab of wind-drifted snow in Main Days. This slab failed 8" down and 25' wide on an East Aspect at 10,400'. This avalanche likely on the faceted snow surface from before the new snow yesterday.
Photo: Tucker
An observer traveling in Broads Fork of BCC noted a recent glide avalanche on Bonkers (ENE facing at 10,100’). Rimmed to the west by steep and smooth quartzite slabs, Broads Fork is a well-known area for natural glide avalanches. Stairs Gulch to the west of Broads and Mill B South to the east are also known for glide avalanches. I wouldn't be surprised to hear of another glide release in this terrain with the continued warm temps. Here is more info on glide avalanches.
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Avalanche Problem #1
Normal Caution
Type
Location
Likelihood
Size
Description
Overall, the avalanche danger is LOW, and normal caution exists. Although avalanches are unlikely, they are not impossible. In isolated areas, you may encounter:
  • Pockets of fresh wind drifted snow along exposed ridges and in open terrain at the mid and upper elevations. One to three inches of new snow can easily be blown into two to six inches thick wind drifts. Although drifts will be shallow and not very wide, wind drifts may be sensitive if they have formed on top of weaker snow underneath.
  • Small loose-wet avalanches in steep features on southerly aspects if the sun comes out this afternoon, or thin clouds allow for some greenhousing to occur.
  • A larger avalanche breaking down into faceted snow in steep, thin, rocky terrain on aspects facing northwest through east, and even southeast at the mid and upper elevations.

Evaluate each slope and look for any signs of instability. Remember that low danger is not the same as no danger.
Additional Information
What happened to the Persistent Weak Layer problem? The PWL problem first appeared in the December 1 forecast. Since then, numerous large natural and human-triggered avalanches have occurred, failing on the layer of faceted snow on mid and upper-elevation aspects facing west, north, east, and southeast. It is now unlikely a skier or rider could affect this deeply buried layer. While we acknowledge we have a poor structure of strong snow over weak snow, time has allowed this structure to become temporarily stable or "dormant". While this problem has become dormant, the problem is not extinct, and it may again become reactive with future storms or a new load. Forecaster Greg Gagne was in Porter Fork of Mill Creek Sunday and well explains the situation below.
General Announcements
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.