In partnership with: Utah Division of State Parks and Recreation, The Friends of the Utah Avalanche Center, Utah Department of Emergency Services and Homeland Security and
“keeping you on top”
December 23, 2007 7:30 am
Good morning, this is
A clipper passing to the northeast of us brought cloudy skies and a few flurries, but I’d expect to see the skies opening in the afternoon. Temperatures have rebounded 15-25 degrees from yesterday’s lows below zero and are comfortably in the mid teens at most locations. The northwesterly winds hounded the upper elevations blowing 20-25mph with the ridgeline anemometers recording hourly averages of 35-45 with gusts to 60. 5”+ of settlement improved riding and trail-breaking conditions, but the winds will take their toll.
Avalanche control work at the ski areas continue to produce very large monsters 3-5’ deep, with some breaking to the ground in uncompacted terrain. Highway control work in Stairs Gulch produced a 4-5’ deep crown, which then sympathetic’ed another, smaller pocket 2’ deep. Collapsing into the interface snow prior to last Tuesday’s storm remains prevalent, and tests indicate this layering remains slow to heal. One skier off of Hellgate/Cardiff (google image, photo, fracture line profile) confirmed these suspicions as he remotely triggered a 1-2’ deep and 150’ wide avalanche on a steep west northwest facing slope above Little Cottonwood Canyon. Collapsing the slope on his first few turns, he watched the snow buckle 75’ below, then turned and headed back to the ridge. Brett’s photo gallery/outing can be found here.
New wind drifts will be the main player today as drifts up to 2’ deep are likely to be triggered on the steep loaded aspects. They’ll be more prevalent on the south through easterly aspects, but watch for channeling off the ridgelines and around the subridges and breakovers. Ski cuts, test slopes, and cornice drops should be effective with these new soft slabs, or drifts. It’s possible these may step into the interface from last week, producing much deep, wider slides. Remotely triggered slides are still possible on a variety of aspects.
It’s been over a week now that anyone triggered an avalanche into the old basal snow, and the added snowfall from last week’s storms has made it much more difficult for folks in the backcountry to trip the switch on these. Nevertheless, ski areas are still able to move snow down to these layers and it’s not taking a crow bar to pull these things out. So, there continue to be places where a person could still trigger a slide on the weak facets near the ground. These would be in shallower snowpack areas, including steep rollovers or in shallow rocky areas, on the steep, upper elevation shady slopes. There slides triggered in a shallow area will propagate into the deeper snow pack, resulting in large, dangerous slides 3 to 5 feet deep.
Bottom Line for the
The avalanche danger will rise to CONSIDERABLE this morning on any steep wind drifted slopes, and may be more prevalent on south through east facing aspects. Other slopes steeper than about 35 degrees have a MODERATE danger, with isolated areas in the shady terrain where avalanches may step down 3-5’ deep.
Cloudy skies will turn
partly cloudy by the afternoon. The
northwesterly winds will continue to blow 25-35mph. Temperatures will rise to the mid-twenties at
8000’ and upper teens at 10,000’. The
Christmas Eve storm looks to offer 10-16” in favored areas with a parade of
storms on its heels.
Wasatch Powderbirds will operate outside of the
For an avalanche education class list, updated 12/22/07, click HERE.
If you want to get this avalanche advisory e-mailed to you daily click HERE.
The UAC has temporary job openings for doing avalanche outreach in more rural areas. Click HERE for info.
UDOT highway avalanche control work info can be found HERE or by calling (801) 975-4838.
Our statewide tollfree line is 1-888-999-4019 (early morning, option 8).
For our classic text advisory click HERE.
If you’re getting out and see anything we should know about please let us know. You can leave a message at (801) 524-5304 or 1-800-662-4140, or email us at [email protected]. (Fax 801-524-6301)
The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
I will update this advisory by 7:30 Monday morning.