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, February 17, 2003

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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, February 17, 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 the Uinta Brewing Company.

Current Conditions:

Yesterday Bruce was able to visit the site of Saturday’s accident on Gobbler’s Knob. Preliminary information about the accident is available in the accidents section of www.avalanche.org and I will update the extended line by 9am (364-1591).

An energetic cold front moved through the Wasatch yesterday afternoon. This system was accompanied by strong southwest winds and an impressive display of thunder and lightning. It also laid down a nice layer of graupel. Snowfall totals from yesterday are 5 to 8 inches of snow and just under an inch of water in the Cottonwood Canyons, 4 inches of snow and a half inch of water in the Ogden and Park City mountains, and an inch of rain followed by an inch of snow in the Provo mountains.

Temperatures this morning are in the mid teens at 8,000’ and low teens at 10,000’. Overnight the winds have been from the west and northwest. In most areas overnight wind speeds were in the 10 mph range, but along the high ridgelines sustained speeds were over 20 mph with gusts in the 30’s most of the night.

Avalanche Conditions:

Yesterday strong winds and new snow caused a marked increase in the avalanche danger. Backcountry observers noted that the fresh wind drifts were a bit sluggish on 30 degree slopes, but didn’t need much encouragement on slopes approaching 40 degrees in steepness.

A group in Cardiff Fork triggered a fresh wind drift about a foot deep and 50’ wind on a northeast aspect. In the Wolverine Circ a skier was able to trigger several wind drifts, but one in Huge Chute broke about 30” deep and 70’ pulling out snow to the ground on one side. That slope faces northeast and is near 40 degrees. Also a skier in Big Cottonwood Canyon was caught and was briefly buried in a slide about 1’ deep and 40’ wide.

The main avalanche concern today will be the wind drifts that formed with southwest winds yesterday and northwest winds overnight. The winds were quite strong so look for mid-path wind pillows and drifts in other odd places. They could be stubborn today, but you will still be able to trigger then on the steeper slopes. Also with an inch of water in the last 24 hours and 2 inches in the last three days, the chances of triggering a deep slab avalanche have increased. The areas where you can trigger a deep slab remain localized, but as we saw on Saturday the consequences can be severe. Remember that wind slab avalanches are great triggers for deep slab avalanches.

Lastly, the cloud cover will be increasing today, but direct sun could trigger sluffs in the new snow this morning.

Bottom Line (SLC and Park City Area Mountains):

The avalanche danger is CONSIDERABLE today on any steep slope with recent wind drifts. There is also a MODERATE danger of triggering an avalanche into deeper weak layers on northwest, north, northeast and easterly facing slopes, steeper than about 35 degrees and above about 9,000 feet.

Bottom Line (Ogden and Provo Mountains):

The avalanche danger is MODERATE today on any steep slope with recent wind drifts. In the upper portions of the Provo Area Mountains the avalanche danger may be CONDSIDERABLE. There is also a MODERATE danger of triggering an avalanche into deeper weak layers on northwest, north, northeast and easterly facing slopes, steeper than about 35 degrees and above about 9,000 feet.

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

Mountain Weather:

Today moist westerly flow will bring mild temperatures, light winds, and snow flurries to the mountains. Temperatures will rise into the upper 20’s at 8,000’ and mid teens at 10,000’. The wind will be from the west in the 15 mph range. Clouds will be building during the day and we may see an occasional snow shower. A weak disturbance will move through northern Utah on Tuesday, and a stronger system is forecast for Thursday.

General Information:

Wasatch Powderbird Guides will be flying in the American Fork drainage today.

To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, remember that the information you have could save someone’s life. 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. 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!

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National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

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