Skyline Avalanche Advisory

Forecaster: Grant Helgeson

AVALANCHE WARNING »

Dangerous avalanche conditions are occuring or are imminent. Backcountry travel in avalanche terrain is not recommended.
Notice:

This AVALANCHE WARNING is for all the mountains of Utah. Recent snow and expected more snow on top of an already weak snowpack is PRODUCING DANGEROUS AVALANCHE CONDITIONS. Numerous accidents have occurred over the last few days and more are probable if people venture onto steep avalanche terrain this weekend. People are advised to avoid steep avalanche terrain over the next few days.


BOTTOM LINE

Danger by aspect and elevation on slopes approaching 35° or steeper.
(click HERE for tomorrow's danger rating)


Danger Rose Tutorial

Dangerous avalanche conditions exist. The avalanche danger is HIGH. Continued loading of an already weak snowpack is producing widespread natural avalanche activity. People are advised to avoid steep avalanche terrain through the weekend.

Strong winds have created sensitive wind slabs on High & Mid elevation slopes that face W, NW, N, NE & E. The recent storm has also reactivated the hazard of large destructive avalanches failing near the ground taking out the entire season's snowpack in large catastrophic avalanches.


CURRENT CONDITIONS

This week's storm totals are around 18" on the Skyline. We desperately needed the snow, but, for the moment we may have too much of a good thing. While the riding conditions have improved dramatically, the snowpack needs time to adjust to this new load.


RECENT ACTIVITY

As riders we often forget about our buried layers in the snowpack. Two weeks ago we had a rain event to ridge top. Weak layers form just above and below crusts. So, we had a very weak surface when this storm system arrived early this week.

Consequently, we've observed avalanche activity where the weak snow below the rain crust is the culprit. Strong winds have whipped our 18" of new snow into sensitive wind slabs, and we've seen these fail naturally on north through east facing slopes across the Skyline.


THREAT #1

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

There is a very specific recipe for avalanches. We need a bed surface, a weak layer, and a slab. We've had the first two ingredients for months now, now we’ve got the slab. This week’s storm has laid down over 18" of 10% density snow, accompanied by strong winds primarily out of the southwest. We now have a sensitive wind slab resting on a snowpack riddled with weak layers. We can expect hard slab avalanches on all mid and upper elevation lee aspects. Depths will range from 18" to taller than your average rider. As the slabs mature, they will get spookier. These will be unmanageable avalanches, breaking above you and failing as big chunky blocks. Our best bet is to stay out of avalanche terrain this weekend, sticking to low angle terrain (30 degrees or less) well away from the big slopes.


THREAT #2

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

We have an incredibly weak snowpack structure in place that the recent storms have brought literally to the breaking point. The sickening sounds of very large settlements are the norm on the Skyline right now. That "whoomphing" sound indicates buried layers failing catastrophically.

This new load has re-activated the facets or "sugar snow" that rests just above the ground. Consequently, deep hard slab avalanches failing at the dirt and taking the entire season's snowpack to the bottom of the hill are probable. These will be deep, destructive & un-survivable hard slab avalanches.

Travel in avalanche terrain is not recommended at this time.


MOUNTAIN WEATHER

Welcome to winter eh? We'll see another 3 inches or so of snow today accompanied by winds out of the west - northwest around 20 mph. We can expect another 3" of snow overnight with the storm tapering off by mid-day Sunday. A brief bout of high pressure will bring overnight low temperatures down to the single digits early next week. More snowfall is forecast as we move into the week, but snowfall amounts are hard to pin down at this time. Likely just a few inches a day mid week before another period of high pressure moves in Friday.


GENERAL ANNOUNCEMENTS

See or trigger an avalanche? I'd like to hear about it. You can reach me on my mobile: 801-824-0305, or shoot me an email: grant@utahavalanchecenter.org Observers may choose to remain anonymous if they wish.

I will update this forecast by 7am Saturday January 30th.


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


This advisory provided by the USDA Forest Service, in partnership with:

The Friends of the Utah Avalanche Center, Utah Division of State Parks and Recreation, Utah Division of Emergency Management, Salt Lake County, Salt Lake Unified Fire Authority and the friends of the La Sal Avalanche Center. See our Sponsors Page for a complete list.