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

The Utah Avalanche Center Home page is: http://www.avalanche.org/~uac/

Avalanche advisory

Saturday, February 22, 2003

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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 Saturday, February 22, 2003, and it’s 7:30 in the morning. We would like to acknowledge one of our partners, the Friends of the Utah Avalanche Center, generously supported by Uinta Brewing.

Current Conditions:

Ridge top winds this morning have diminished somewhat. Yesterday, they were blowing hard from the west at 30mph and gusting to 50 along the highest peaks and they drifted quite a bit of snow on the upper elevation ridges. This morning, ridge top winds are from the west, blowing around 15-20 with ridge top temperatures in the mid teens.

Avalanche Conditions:

Today the big news is a very welcome snow storm. The cold front should arrive around 9:00 the morning and it looks like we will get 6 inches to as much as a foot of new snow by tonight when things slow down.

So how is this going to affect the avalanche danger? Like most avalanche questions--it depends. The first rule of avalanche forecasting is that you start with the pattern of the pre-existing snow. Most of the snow in northern Utah at upper elevations is fairly deep and stable, so the weight of the new snow probably won’t affect it too much unless we get much more snow than we expect. But the big, scary exception is that some places have a thin and consequently weak snowpack and any additional weight will make it cranky. A week ago today, a backcountry skier triggered an avalanche on Gobbler’s Knob, which killed him in exactly this kind of situation on a steep, shallow snowpack, which had been recently loaded with the weight of new snow. In a more recent example, yesterday, some backcountry skiers in No Name Bowl on the Park City ridge line, noticed a fresh—probably natural—avalanche which broke into these deep layers of weak, faceted snow about 4 feet deep and 100 feet wide. The trouble is that you need x-ray glasses to tell the difference between safe snow and dangerous snow today, so unless you’re willing to do a lot of digging and poking around, you should probably play it conservative today. Almost all the old, cagy, avalanche professionals I have talked to recently have resigned themselves to the fact that this is just not the year to jump into steep slopes on shady aspects, and I count myself as one of these.

The second problem is that yesterday the wind blew hard along the ridges and a number of people, myself included, found localized areas of fresh wind drifts on steep slopes that we could trigger easily. Today’s new snow will cover up those wind slabs, making them invisible. Today, you should definitely be suspicious of steep slopes in upper elevation, wind-exposed areas, especially east through south facing slopes. If you must mess around with them, kick some cornices first and put in a good slope cut before you commit yourself.

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

The avalanche danger is CONSIDERABLE at upper elevation, wind exposed, steep slopes with recent deposits of wind drifted snow. There is also a MODERATE or localized danger of triggering an avalanche on deeper weak layers of old, weak, faceted snow on slopes that face northwest, north, northeast and east, steeper than about 35 degrees and above about 9,000 feet, especially in thin, rocky areas and the danger will likely rise to CONSIDERABLE later today in this kind of terrain.

Western Uintas – call 1-800-648-7433 or click here for weekend and holiday forecasts.

Mountain Weather:

As I said, 6 inches to perhaps a foot of snow today. Remember that probably only 4-wheel drive or chains will be allowed in Little Cottonwood Canyon today. The storm will start with westerly ridge top winds and they will turn northwesterly by afternoon. Ridge top temperatures today should be in the mid teens and drop to around 5 degrees overnight with 30 mph winds from the west this morning, switching to the northwest by afternoon and dropping to around 20 mph. 8,000’ temperatures should be in the mid 20’s and drop to around 10 overnight. For the extended forecast, we have a cloudy, snowy week coming up with warmer southwest flow on Monday though Wednesday and continued clouds and light snow showers on a westerly flow through the end of the week.

General Information:

Wasatch Powderbird Guides will probably not be flying today due to weather but if they do get out they will be in Days, Silver, Cardiff, White Pine and American Fork, with a home run in Grizzly Gulch.

To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, please leave a message on our answer machine at (801) 524-5304 or 1-800-662-4140, or email to [email protected] or fax to 801-524-6301. Your information could save someone’s life. 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.

Ethan Greene will update this advisory by 7:30 on Sunday morning.

Thanks for calling!

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National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

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