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

Wednesday, December 18, 2002

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Good Morning. This is Evelyn Lees with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory. Today is Wednesday, December 18, 2002, and it’s 7:30 in the morning.

I have continued the Avalanche Warning for the mountains of northern and central Utah. There is a high avalanche danger, and both natural and human triggered avalanche activity is expected to continue today.

Current Conditions:

With a predominately westerly flow, the storm evenly loaded the northern Utah mountains. Storm totals so far are averaging 18 to 24” of snow, with water equivalents of 1 ½ to just over 2” of water.

This morning, there are partly cloudy skies in the mountains, with occasional snow showers. Winds overnight have been from a westerly direction, averaging 10 to 15 mph, with gusts in the mid 20’s. On a few of the higher peaks, hourly averages are in the mid 20’s, with gusts 35 to 40 mph. Temperatures have been dropping and are now in the chilly single digits to low teens.

Many of the resorts will be conducting control work in their unopened areas, and are closed to backcountry travelers.

Avalanche Conditions:

In December, the snowpack in the northern Utah mountains became unusually weak during the long, cold dry spell. Multiple layers of weak facets, depth hoar, feathery surface hoar crystals and slick crusts developed, and have made a very poor base for all the new snow.

Yesterday, there was wide spread avalanche activity reported in the backcountry and at the resorts. Natural activity reported included the Monitors, Meadow Chutes and many slopes in the Provo area mountains. Most active slopes were northerly and easterly facing, but basically, on any slopes where there was old snow on the ground before this storm avalanches were being reported. This includes elevations as low as 7,500’, and on southerly facing slopes at the mid and upper elevations that held snow. Many slides were being triggered remotely from the flats or from a considerable distance away with large collapses and shooting cracks. The slides were averaging 1 ½ - 2 feet deep, and up to 700’ wide. Most slides were breaking in the facets near the thin rime/rain crust, though some were going to the ground.

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

The avalanche danger is HIGH today on most slopes above 7,500’. Both human triggered and natural avalanches are likely. Stay off of and out from under steep slopes. Travel near or in terrain traps such as steep road banks and gully or stream bottoms should be avoided.

Mountain Weather:

Northern Utah will be under a moist and unstable northwest flow today. Expect occasional snow showers, with additional accumulations of 3 to 6”. Winds will be from the west to northwest, averaging 15 to 25 mph across the ridges. Tonight, decreasing snow showers, with another 3 to 6” possible. Continued moderate northwesterly winds, and lows around 10. The break on Thursday will be followed by more snow on Friday through the weekend.

General Information:

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 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.

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

Thanks for calling!

________________________________________________________________________

National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

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