Wasatch Cache National Forest

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Avalanche advisory

THURsday, FEBRUARY 28, 2002 7:30 AM

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Good morning, this is Tom Kimbrough with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Thursday, February 28, 2002, and it’s 7:30 a.m.

Current Conditions:

Clouds and strong westerly winds moved into northern Utah overnight. Winds are now blowing 15 to 25 mph over the ridges, with speeds up to 40 with gusts to 50 on the highest peaks. Mountain temperatures are in the teens. A cold front, arriving about midday, should give us a little new snow later today.

Snow surface conditions are just about everything you can imagine, with some settled powder on sheltered shady slopes.

Avalanche Conditions:

There were no avalanches reported from the backcountry yesterday but recent strong winds and a little new snow a few days ago produced several human triggered slides earlier this week. These avalanches occurred mostly on north through east aspects above 8,500’. The winds were strong enough to drift slopes well below the ridgelines and cross load the sides of gullies and sub-ridges. On Sunday a group of skiers triggered a wind slab on the side of a cross-loaded gulley in Cardiff Fork. The slide broke on a northwest facing slope at about 9,800’. On Monday a skier in Mineral Fork triggered a slide (photo1, photo2) on an east facing slope at about 8,700’.

Winds have picked up again from the west and northwest. Although widespread wind and sun crusts will limit how much snow can blow around, be alert for fresh drifts. If we get a few inches of new snow this afternoon, expect shallow but sensitive drifts to develop quickly on the many crusted slopes. The crusts will allow any triggered slides to move quickly and run far. Under the varied surface snow are plenty of weak layers that complicate the stability picture. These deeper weak layers mean that in some places avalanches in the newer snow may break down into deeper layers. The stability in the Wasatch Mountains is currently quite variable and winter travelers need to evaluate each slope before crossing it.

In areas sheltered from the sun and wind, the loose snow is sluffing easily on slopes up around 40 degrees steepness.

Bottom Line:

The danger of human triggered avalanches is MODERATE on slopes steeper than about 35 degrees with recent deposits of wind drifted snow. Human triggered avalanches are possible in these areas. There remains a distinct possibility that any new avalanche may step down into older snow. Suspect areas for this would be upper elevation steep rocky chutes, areas that have slid earlier in the year and in areas that have a thinner snowpack.

(Provo Area Mountains and Western Uinta Mountains)

These areas have had a thin snowpack most of the winter, and the sugary weak snow is more widespread. The danger of human triggered avalanches is more widespread in the Provo and Western Uinta Mountains, especially where wind drifted.

(Ogden Area Mountains)

Reports indicate that the avalanche danger is higher in the Logan Area Mountains. Use extra caution while traveling in the northern portion of our forecast area and approach slopes greater than 35 degrees with care.

Mountain Weather:

A very cold but mostly dry weather system will move into Utah today. A cold front will drop south along the range, reaching the Salt Lake area about midday. Expect developing snow showers, possibly heavy during the passage of the cold front, and continuing into the afternoon. While snowfall should taper off rather quickly in many areas, it may linger into the evening in the Cottonwood Canyons. Ridge top winds will be 20 to 35 mph from the west, shifting northwest and may get down into lower elevations during frontal passage. Storm totals of around 2 to 4 inches are likely, with 3 to 6 possible for the Cottonwoods. High temperatures will be in the twenties at 8,000 feet, plunging to near zero tonight. Friday should be mostly sunny in the morning with increasing afternoon clouds.

General Information:

The Wasatch Powderbird Guides will be flying in the Cardiff, Days, Mineral, and Silver Fork drainages today with homeruns in White Pine today.

The Banff Mountain Film Festival will be at the U of U’s Kingsbury Hall on March 12 and 13, at 7pm. Tickets are $6.50. Don’t miss this great benefit for the Utah Avalanche Center!

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 uacobs@avalanche .org, or you can fax an observation to 801-524-6301.

For more detailed mountain weather and avalanche information, your can call 801-364-1591, which we’ll try to have updated by around noon each day.

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.

I will update this advisory by 7:30 on Friday morning.

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