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 THE MOUNTAINS OF NORTHERN AND CENTRAL UTAH INCLUDING THE BEAR RIVER RANGE, WESTERN UINTAS, WASATCH, TUSHARS AND MANTI SKYLINE. A POTENT STORM WILL EFFECT THE MOUNTAINS AND OVERLOAD AN EXISTING WEAK SNOWPACK. THIS WILL RESULT IN NATURAL AVALANCHE ACTIVITY. HUMAN TRIGGERED AVALANCHES ARE ALMOST CERTAIN ON MANY HIGH ELEVATION SLOPES. THE UTAH AVALANCHE CENTER IS RECOMMENDING THAT PEOPLE AVOID THE BACKCOUNTRY UNTIL CONDITIONS IMPROVE. THE AVALANCHE DANGER WILL LINGER INTO THE WEEKEND EVEN THOUGH WE MAY SEE SOME CLEARING OF THE WEATHER.


BOTTOM LINE

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


Danger Rose Tutorial

Below treeline there isn't enough snow to ride on just yet.  Nearly all of the West facing aspects are wind scoured and are in poor riding condition.  Above treeline, a combination of fresh wind slabs and large lurking hard slabs exist, especially on East facing aspects.  If you trigger one of the fresh wind slabs, there is potential for it to "step down" and trigger a deep hard slab avalanche.  Increased wind loading will lead to a natural avalanche cycle.  Choose safe routes that keep you out of high elevation avalanche paths.


CURRENT CONDITIONS

Looking at the mountains from the valley, it looks like it's finally go time, and it almost is.  Unfortunately, before this last storm, non wind loaded aspects had little or no snow on them.  This last week of storms put down 21" of light densitry snow on our storm boards, covering virtually everything in a nice blanket of white.  But, there's  no base out there.  We watched a few youngsters try to get through a nearly flat meadow in the Millers Flat area with very little success.  Why?  Because there isn't anything for the track to hook up on yet.  Give it some time to settle and perhaps another storm cycle and traveling conditions will improve.  However, if you feel yourself suddenly on a "solid" piece of snow after snaking through the fluffy stuff, be aware that you're likely on top of a wind slab, and you're now in the sights of the avalanche dragon.


RECENT ACTIVITY

They say that when a person looses sight, they develop an acute sense of hearing.  Truth be told, we couldn't see much at all out there on Friday.  But, we heard enough whoomphing to blow down a brick house.  That "whoomphing" sound is the snow pack telling us it's weak, and it's failing in compression.  Interestingly, it was often the third or fourth person that touched the magic weak spot in the snow and got the audible whoomph.  What does this mean to you?  It means that if you're buddy gets stuck on a slope, you should watch him carefully from afar.  You putting your weight on the snow next to him might just trigger the lurking hard slab.  If you both get buried, who's going to help?


THREAT #1

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The honking Westerly winds made for some pretty hateful driving on Hwy 31 on Friday, I saw a few big rigs stuck in the snow bank.  That being said, highway 31 is fairly sheltered when compared to the ridge tops.  On the summit ridges the wind was gusting above 40 mph, scouring the windward West facing aspects and building a sizeable soft slab on the lee East facing aspects.  I came across a fresh slab that was over 4' deep this afternoon.  While it looks like Tuesday's storm snow went through a natural cycle, the Christmas snow hasn't yet done so.  In short, it's due, just waiting for an additional load to trigger it.  My concern is that these fresh slabs will start moving and "step down" into our deeper hard slabs potentially triggering a large destructive avalanche.


THREAT #2

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The hard slabs are still luring out there on the East facing aspects.  They are not as easy to spot now, as they're sitting underneath 2' of nice light density storm snow.  These big destructive hard slabs are sitting on the proverbial house of cards, the weak facets near the ground.  At the moment, the travel conditions are marginal, which will make it hard to get near these big slabs.  But, as things settle out it will be possible to get a machine into these kinds of aspects.  Pay attention to the wind.  If it's loading a slope you're planning to ride, it's best to re-think that decision.  If you suddenly find yourself on a firm supportive piece of snow, it's likely one of these slabs!  While they will be harder to trigger than the fresh wind slabs, once moving, these will be incredibly destructive.


GENERAL ANNOUNCEMENTS

There were A LOT more rigs out there this weekend compared to last.  If you see or are involved in an avalanche, or just see something you think would interest me, please send me a heads up!


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.