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

sUNday, FEBRUARY 17, 20024:00 PM

 

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Good afternoon, this is Tom Kimbrough with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.Today is Sunday, February 17, 2002, and itís 4:00 p.m.

 

Current Conditions:

A change in the weather is on our doorstep.Southerly winds have been blowing at the upper elevations all day.Speeds are 10 to 20 mph at 10,000 feet and 20 to 40 across the highest peaks.Temperatures have warmed into the thirties at 8,000 feet and the mid twenties at 10,000.The backcountry snow conditions havenít been quite up to our usual standards recently but a change in the weather will hopefully freshen things up over the next couple of days.

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Avalanche Conditions:

There was an avalanche accident high on the southeast side of the American Fork Twin Peak this morning.A skier triggered a hard slab avalanche that broke around the old January 6 ice crust.This is the same layer that was responsible for a major avalanche cycle in late January and early February.The slide broke about 120 feet across and 1 to 4 feet deep.The slope was southeast facing at about 11,500 feet.The person, an experienced avalanche worker, was injured as he was carried over a rock band.Fortunately, it sounds like he will be OK.This is one of the few above timberline slopes that did not avalanche during the storm on January 28 and it was also drifted by the strong winds last Thursday.The initial slide also released a second similar slab avalanche below and to the left of the first one.

 

While not directly related to the rise in avalanche danger that we expect with tonightís approaching storm, this avalanche does remind us that there is still a lingering chance of triggering hard slab avalanches and that slides in new snow that we may get this week may step down into deeper weak layers.

 

The avalanche danger is already rising as winds increase this afternoon.The danger will continue to rise tonight and Monday as snow accumulations add up and winds build drifts on mountain slopes.A couple of months of cold temperatures and small, infrequent storms has produced a weak snowpack that wonít support much extra weight.There is lots of faceted snow at the surface on shady slopes and widespread areas of loose, unsupportable snow at the mid and lower elevations.Sun crusts on the southerly aspects and old wind slabs along the upper elevation ridgelines will provide sliding surfaces for new snow avalanches.In other words, if this next couple of storms put down one or two feet of new snow, plenty of avalanches are likely.

 

Bottom Line:

While the danger of human triggered avalanches is isolated or LOW today on most slopes, there is a MODERATE and rising danger on steep wind drifted slopes at upper elevations. The danger will continue to increase and become more widespread as snowfall begins tonight and continues on Monday.

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(Provo Area Mountains)

Mostly the same general conditions as in the SLC mountains.

 

(Ogden Area Mountains)

Mostly the same general conditions as in the SLC mountains.

 

Mountain Weather:

Much of the approaching stormís energy will track through southern Utah tonight but the northern mountains could get a trace to a couple of inches before dawn, with another 2 to 4 on Monday.Tomorrow winds will shift from the southwest to the northwest with snowfall continuing for much of the day, especially in areas like the Cottonwood Canyons.Ridge top winds will average 20 to 35 mph from the SSW into this evening.Low temperatures will be in the teens tonight.The snow level may start near 6,000 feet, dropping to the valley floor before dawn.There may be a break on Tuesday with another warm and very windy storm for late Tuesday into Wednesday.

General Information:

During the Olympics, we will issue both morning and afternoon advisories.Weíll use the 364 -1591 line for more detailed or additional avalanche information.

 

To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, you can leave a message at (801) 524-5304 or 1-800-662-4140.Or you can e-mail an observation to [email protected] .org, or you can fax an observation to 801-524-6301.

 

Wasatch Powderbird Guides will not be flying during the Olympics.

 

We have a new icon-based, short advisory posted each day at www.avalanche.org.We would appreciate any feedback on this new product.

 

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.

 

Drew Hardesty will update this advisory by 7:30 am on Monday.

Thanks for calling!

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For more detailed weather information go to our Mountain Weather Advisory

National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

http://www.avalanche.org/usdanger.htm