Uintas Avalanche Advisory

Forecaster: Craig Gordon

SPECIAL ANNOUNCEMENT

A Special Avalanche Advisory has been issued for the western Uinta Mountains. An unusual snowpack has created tricky and unpredictable avalanche conditions, resulting in several close calls in recent days. Today’s expected warm temperatures will lead to an elevated avalanche danger. Human triggered avalanches are likely, especially on mid and upper elevation northerly facing slopes. Once triggered, today’s avalanches will break wide and deep, creating a dangerous and possibly unsurvivable slide.

BOTTOM LINE

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


Danger Rose Tutorial

A Level 3 (CONSIDERABLE) avalanche danger exists at all elevations on slopes facing West, Northwest, North, Northeast, and East. Deep, dangerous, and possibly unsurvivable human triggered avalanches breaking into the widespread an persistant layer of buried surface hoar are likely. These are very unusual avalanche conditions for us and we’re seeing avalanches triggered on relatively low angle slopes, breaking in thick stands of trees, islands of safety, and in terrain where we don’t normally see avalanche activity!

As the day heats up the danger of wet avalanches will increase from a Level 1 (LOW) this morning to Level 2 (MODERATE), especially during the heat of the day. Human triggered avalanches will be possible on steep, sunny slopes, particularly at mid and lower elevations.

If you’re traveling along the high ridges in the wind zone above treeline, expect to find a Level 2 (MODERATE) avalanche danger. Human triggered avalanches are possible, particularly on steep wind drifted slopes in terrain facing the north half of the compass.

CURRENT CONDITIONS

A short-lived ridge of high pressure allowed skies to clear overnight. South and southwest winds are blowing 15-25 mph along the high ridges and temperatures are in the low to mid 20’s. The combination of low clouds and high humidity greenhoused much of our low and mid elevation terrain yesterday. However, cold, creamy powder will still be found on upper elevation north facing terrain.

RECENT ACTIVITY

Yesterday, a very knowledgeable and experienced sledder triggered a hard slab 3' deep and 200' wide, while stuck in a tight spot near the top of the slope. The slide carried the rider through a group of trees where he was partially buried, but quickly dug out by his partners. He did, however, sustain some leg injuries and we wish him all the best. Check out this amazing footage. We'll be visiting the site today and will post more information on Friday.

Also, it’s been an active week in Weber Canyon with two large human triggered slides in the past few days. The first occurred late Saturday on a 33 degree Northwest facing slope at about 9,200’. Averaging 3’ deep and 150’ wide, this remotely triggered slide broke on facets and decomposing surface hoar below the raincrust. Click here for more details.

Tuesday, a local backcountry skier remotely triggered a hard slab from about 75’ away on a Northwest facing slope at 10,000’ near Slader Ridge. 2’-3’ deep and several hundred feet wide, the slide occurred when the second skier was eight turns downslope. Thanks for the great write up JG! Click here for more details.

Huge thanks to all those who continue to submit all the very informative observations. The information is GREATLY appreciated!

THREAT #1
WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

In the past few days there have been several close calls by very experienced backcountry riders, who have triggered deep dangerous slides from a distance, from low on the slope, and from adjacent terrain hundreds of feet away. This isn’t steep, radical, extreme terrain we’re talking about. These folks, much like me and my colleagues, are conservatively choosing low angle terrain to avoid the tricky avalanche conditions. Problem is- we’re dealing with a very unusual layering in our snowpack, centering on the now deeply buried raincrust and the facet/surface hoar combo which lurks underneath. All the large slides we’ve looked at have a common theme- recent warm temperatures have created a dense slab, now 3’-4’ deep, which sits on a slick bed surface and all of this rests on weak snow underneath. The structural makeup of our snowpack is not only inherently spooky, it’s tricky because you can ride plenty of slopes and not trigger a large dangerous slide, but move over a couple hundred feet and BAM… you’ve got a huge avalanche on your hands. Your best bet to avoid triggering a large, dangerous and possibly unsurvivable avalanche is to stay off of and out from under all steep slopes, especially those facing the north half of the compass. Also, avoid thinner looking portions of the snowpack where bushes, rocks, or small trees are poking through, especially if that’s connected to a steeper slope. Finally, think about the consequences of triggering a slide and chose terrain accordingly. Remember- avalanches can be triggered from a distance even on relatively low angle terrain so be aware of steep slopes above and those connected to the terrain you’re riding in.

THREAT #2
WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The sun is high in the sky and wet avalanches are beginning to become an issue. As the day heats up, you’ll want to get off of steep, sun exposed slopes and avoid terrain traps like gullies, creek bottoms, and road cuts where avalanche debris can pile up deeply.

THREAT #3
WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

A few stubborn wind drifts along the leeward side of the high ridges may still be reactive to the weight of a rider. Once triggered, today’s slabs could break into weaker layers of snow creating a large, unmanageable slide. Continue avoiding steep, wind drifted slopes, especially if they appear fat and rounded or sound hollow like a drum.

MOUNTAIN WEATHER

A southerly flow ahead of an approaching storm system will result in breezy and warm conditions over the area today. Highs reach into the upper 30's and overnight lows dip into the low 20's. South and southwest winds will average in the 20's with gusts in the 40's along the high peaks. A storm system will graze Northern Utah this evening and overnight, pushing through a cold front and bringing some light snow. High pressure strengthens Friday before another weak system impacts Northern Utah on Saturday.

GENERAL ANNOUNCEMENTS

The information in this advisory expires 24 hours after the date and time posted, but will be updated by 7:00 AM Saturday, Mar. 12th, 2011.

If you’re getting out and about and trigger an avalanche or see anything interesting please let us know here. Or drop Craig an email : craig@utahavalanchecenter.org or call 801-231-2170

The western Uinta advisory program is going full tilt and forecasts will be issued by 7:00 AM on Wednesday, Saturday, Sunday and all holidays.

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.