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

Monday, December 30, 2002

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Good Morning. This is Ethan Greene with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Monday, December 30, 2002, and it’s 7:30 in the morning.

Current Conditions:

A Pacific Storm brought blustery conditions and license plate snow to the Wasatch Mountains yesterday. The system laid down about 8 inches snow and a little more than 0.5 of water before splitting and dropping a disappointing 2 inches of snow overnight. Last night temperatures dropped into the low teens at 8,000’ and upper single digits at 10,000’. In mid-elevation areas the winds have been from the west in the 10 mph range with gusts over 30 mph. Along the high peaks the winds have been in the 25 mph with some gusts over 60 mph.

The snow surface is generally covered with new snow and wind drifts. Southerly aspects have a variety of sun crusts from Saturday. The upper snowpack has become stronger, but it is still easy to punch through especially on steep slopes.

Avalanche Conditions:

A few days of warm temperatures have increased the stability of our snowpack. Unfortunately, since the snow was so weak, this brief stability increase may have only make conditions more tricky. Yesterday there were two human triggered avalanches reported from the upper part of Big Cottonwood Canyon. They occurred on northwest and east facing slopes above 9,000’ that were 35 degrees or steeper. Each avalanche was 1 to 2 feet deep and 20 to 40 feet wide. One of these avalanches broke well above the skier who triggered it, but they were able to ski off to the side without incident.

Avalanche control work at the ski areas also produce some interesting results. In a northeast facing area of the Park City Mountains, avalanche workers found several wind slabs up to 3 feet deep and 150 feet wide. These slabs were easy to release with ski cuts on slopes in the 35 degree range. They also had one sympathetic release (an avalanche that triggered another avalanche) 400’ away. Explosive control work in the Ogden Area Mountains triggered an avalanche up to 5 feet deep and 200 feet wide. This avalanche occurred on a northeast aspect at about 9,000’.

Today you will have to look out for both new and old wind deposits. Ten inches of new snow and westerly winds will create sensitive drifts on easterly slopes. We continue to see avalanche activity on buried layers of faceted snow. A few days of warm temperatures have increased the stability of our snowpack. However, this is not good new for upper elevation areas where it is now stabile enough for you to travel well onto the slab before it fractures.

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

The avalanche danger is CONSIDERABLE today on northwest, north, northeast and east aspects above about 9,000’ that are about 35 degrees or steeper. There is a MODERATE avalanche danger on any steep slope with recent wind drifts, and on south and southwest facing slopes and slopes less than about 30 degrees the avalanche danger is generally LOW.

Bottom Line (Ogden Area Mountains):

The avalanche danger is CONSIDERABLE today on northwest, north, northeast and east aspects above 8,000’ that are about 35 degrees or steeper. There is a MODERATE avalanche danger on any steep slope with recent wind drifts, and on south and southwest facing slopes and slopes less than about 30 degrees the avalanche danger is generally LOW.

Mountain Weather:

A ridge of high pressure over northern Utah will move eastward today ahead of a strong Pacific Storm. Winds will be from the west in the 20 mph range this morning and shift to the southwest during the day. Clouds will be building during the day, and skies will become mostly cloudy by the afternoon. Temperatures will rise into the mid 20’s at 8,000’ and to near 20 degrees at 10,000’. Wind speeds will increase into the 30 mph range tonight. The Ogden and Logan Area Mountains should pick up a few inches of snow overnight and snow showers will spread southward tomorrow morning. How much snow we get depends on how much this storm splits. If it comes through as advertised the Ogden Area Mountains could see a foot or more by Tuesday evening. I expect 5 to 8 inches in the Salt Lake Mountains by Tuesday evening with snow falling into Wednesday.

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.

Bruce Tremper will update this advisory by 7:30 on Tuesday morning.

Thanks for calling!

________________________________________________________________________

National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

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