Wasatch Cache National Forest

In partnership with: The Friends of the Utah Avalanche Forecast Center, Utah Department of Public Safety Division of Comprehensive Emergency Management, Salt Lake County, and Utah State Parks


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Avalanche advisory

Tuesday, December 31, 2002

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Good Morning.This is Bruce Tremper with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.Today is Tuesday, December 31, 2002, and itís 7:30 in the morning.


Current Conditions:

As 6 am this morning, the Cottonwood Canyons have about 3 inches of new snow on a southwesterly flow with 4-6 inches in Farmington Canyon, Ben Lomond Peak, Timponogos and the Uinta Mountains.The snow is about 10 percent water weight, which is about medium density for Utah and more dense than the very light snow on the ground yesterday.Ridgetop winds were blowing around 25 this morning at 4 am from the southwest with gusts as high as 60.Ridge top temperatures are around 20 degrees with temperatures down at 8,000 feet near 27.


Avalanche Conditions:

Yesterday was one of the best days of the year with close to a foot of light, new snow and sunny skies and it really brought everyone out to enjoy life.As you might imagine, some of them also enjoyed seeing some avalanche activity, some closer than they probably wanted.Yesterday there were a couple human triggered avalanches in the Monitors on the Park City-Big Cottonwood ridgeline.They were east facing slopes, one 100 feet wide and another 200 feet wide.One was triggered by a skier as he approached an extremely sensitive cornice from the top.A snowboarder triggered a smaller one in White Pine in Little Cottonwood Canyon on a steep, treed rollover about 20 feet wide and a couple feet deep.Control work at the resorts produced a monster, 250 foot wide slide a couple feet deep on the Park City side of the range and in the Cottonwood Canyons, besides explosive controlled avalanches, one patroller was able to ski cut a slide about 40 feet wide. For more details on these avalanches, call 801-364-1591.All these slides are dry slab avalanches breaking about two feet deep on the old, extremely weak faceted snow that is taking an astounding long time to gain strength.


Weíve had a considerable or higher danger rating for the past two weeks, and in my memory, this is the longest time we have gone with continually scary avalanche conditions.Every day I go into the field thinking that surely we can lower the danger rating from considerable to moderate, but each day, I come back with my tail between my legs being frightened by what I see myself and hear about from others.For instance, yesterday as I tip-toed along the very crest of the rocky ridge between upper Days and Silver Fork, I continually collapsed the snow and one collapse, propagated the fracture onto the slope well below me, where a hanging snowfield about the size of a foot ball field filled with cracks like a spider web.It was only 33 degrees but if it was about 35 degrees or steeper, it probably would have slid, and it certainly would have been an impressive sight from my safe perch on the rock ridge above.Thereís all kinds of slopes similar to this out there still hanging in the balance, where the wimpy weight of a person can make the slope shatter like glass.


As we continue to add weight on top of the fragile, buried weak layers, the danger will only get worse today.Also, this morningís snow is denser than the light fluffy snow on the ground yesterday, so you will likely see some soft, shallow slabs formed from upside-down snow.


Bottom Line (SLC, Park City, Provo and Ogden Area Mountains):

Itís not dangerous everywhere, just on some slopes.The avalanche danger is CONSIDERABLE today on slopes which face the north half of the compass, plus east facing slopes above about 8,500í that are about 35 degrees or steeper and also on any steep slope with recent deposits of wind drifted snow.There is a MODERATE avalanche danger on slopes facing the south half of the compass and a LOW danger on slopes less than 30 degrees, which are not connected to steeper slopes above.


Mountain Weather:

Today, the first half of this storm will probably put down about 6 inches of snow on a southwest flow and then after a short break this morning, this afternoon and New Yearís Eve, the snow should start up again, possibly with lightning, and the flow should turn northwesterly and continue to snow, adding probably another 6 inches of snow and possibly a foot in places favored by a northwest flow such as the Cottonwood Canyons.Ridge top winds will blow around 20 mph from the southwest today, switching to west this afternoon and northwest by tonight and diminish to around 15 mph.Ridge top temperatures are around 20 this morning and should drop to around 6 degrees on New Yearís Day.Snow should end on Wednesday and we should have some nice weather for the rest of the week with the possibly of a little more snow next weekend.


General Information:

Wasatch Powderbird Guides will not be flying today.


The Friends of the Utah Avalanche Center will offer an intensive 3-day avalanche class January 18-20.You can sign up at the Black Diamond Retail Store or call them at 801-278-0233.


To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, call (801) 524-5304 or 1-800-662-4140, or email to [email protected] or fax to 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.


Evelyn Lees will update this advisory by 7:30 on New Yearís Day.


Thanks for calling!



National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings: