Wasatch Cache National Forest
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 Salt Lake County.

“keeping you on top”

AVALANCHE ADVISORY

Sunday, December 09, 2007 7:30 am
Good morning, this is Drew Hardesty with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Sunday, December 09, 2007 and it’s about 7:30 am.

An AVALANCHE WATCH continues for the mountains of Northern Utah. Heavy snowfall overloading a weak pre-existing snowpack warrants a CONSIDERABLE AVALANCHE DANGER as dangerous avalanches continue to be triggered in the backcountry. Backcountry travelers should avoid steep slopes and avalanche runout zones. People without excellent route finding and snow stability skills are urged to use caution if going into the backcountry. This Watch does not apply to ski areas but does apply to terrain just beyond the boundaries and rope lines.

Current Conditions:

The storm’s winding down with a few flakes falling here and there over the range. Most areas picked up another few inches overnight, pushing storm totals for this blockbuster to 20-25” in the Ogden area mountains, 30-35” in the Park City areas, 40-45” in the Cottonwoods, and near 35” with a whopping 5” of snow water equivalent in favored areas of the Provo mountains. Winds are less than 10mph even at 11,000’ and temperatures are in the teens. Trail-breaking is a comical affair and most reported that it was even too deep to make turns. These were the same bemoaning the lack of snow just last week. Mother Nature just can’t win.

Avalanche Discussion:

Explosive control work at the ski areas continues to release larger avalanches into old snow up to 3’ deep. Some were what we call post-control releases, taking out old shot-holes, and releasing in areas that were shot the day before with no results. It’s what an avalanche wife calls Little Cottonwood trickery, but the structure pervades all northwest through northeast areas above 9000’ across the range. We heard about only one significant slide in the backcountry, but that may be more of a function of the trail-breaking conditions than anything. It was in mid-Little Cottonwood Canyon where a skier standing along the Pink Pine ridgeline collapsed the slope, remotely triggering a pocket three feet deep and 40’ wide. It’s a northeast facing slope at about 9500’. Other touring parties, avoiding areas that have the weak base to the snowpack, found minor, manageable instabilities in the new snow.

In the absence of wind, the storm snow instabilities will start to settle out. There’s not usually much trickery here, but continue to perform ski cuts and put only one person on the slope at a time. With a good even blanket of snow, these issues can be found on all aspects and elevations.

I would still warn people to avoid the steep slopes above 9000’ on the northern end of the compass, even areas that released in last weekend’s cycle. I anticipate them becoming less sensitive, but larger and wider and more difficult to survive. The snowpack structure still resembles a load of snow on a house of cards, avalanches may still be triggered from a distance. It adds insult to injury in this situation. Even a touring party on Friday moving on lower angled terrain, triggered a 1-2’ avalanche above and adjacent to them, ripping out a lateral pocket of something that pulled out the week before. There’s no question. Avalanches persist, collapsing seems to be the rule, and snowpits clearly reveal the dirty underbelly of this dangerous snowpack.

There are, however, numerous safe places to recreate today – low and mid elevation slopes facing south, east, and west with a shallower slope angle of 35 degrees.

Bottom Line:

Salt Lake, Park City, and Provo area mountains: The avalanche danger is CONSIDERABLE on northwest, north, and northeast facing slopes above about 9000’ and is exclusive to this terrain. The likelihood is still probable of triggering an avalanche 2-3’ deep into the old faceted snow. The danger is MODERATE for avalanches in the storm snow on all aspects and elevations.

Ogden area mountains: The avalanche danger is MODERATE on mid and upper elevation slopes steeper than about 35 degrees, with human triggered avalanches possible.

Mountain Weather:

We may see a couple more inches today as the storm winds down. Winds should remain light out of the southwest with temperatures in the mid-teens at 10,000’ and in the low twenties at 8000’. A few weaker storms will impact the area over the week.

Announcements:

For an avalanche education class list, 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.