Wasatch Cache National Forest

In partnership with: The Friends of the Utah Avalanche Center, Utah Department of Public Safety Division of Comprehensive Emergency Management, Salt Lake County, and Utah State Parks: http://www.avalanche.org/~uac/

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Avalanche advisory

MONDAY, DECEMBER 29, 2003   7:30 am

 

Good morning, this is Evelyn Lees with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  Today is Monday, December 29, 2003, and it’s 7:30 a.m.  Access to Primrose cirque above Aspen Grove may continue be closed today as the search continues in the aftermath of Friday’s accident.  Photos and information from the incident can be found here.  If you’re having trouble accessing all the photos, simply close the glossary and try again.

 

Current Conditions:

A warm front is approaching northern Utah, and the accompanying strong winds, rising temperatures, and addition of denser snow will create a rising avalanche danger today.  As of 6 am, the southwesterly winds are in the 15 to 20 mph range, with gusts near 40.  Across the highest peaks, hourly averages have increased to near 40, with gusts near 60.  Temperatures have warmed to 15 degrees at 8,000’ and 10 degrees at 10,000’.  Snow should begin in the mountains later this morning, with the heaviest rates this afternoon into this evening.  

 

Snow settlement from the Christmas storm is close to 40%, and yesterday both trail breaking and turning conditions were greatly improved.  Today, very wind sheltered terrain will provide the best protections from the drifting and blowing snow, and the safest traveling conditions.

 

Avalanche Conditions:

There will be an increasing avalanche danger today.  The strong winds have a limitless supply of snow to drift and blow around, and I expect wind drifts one to two feet deep to rapidly form.  These sensitive drifts will be most common on north through east facing slopes, but also look for drifts well off the ridges and cross loaded around terrain features such as gully walls, sub ridges and breakovers.   The growing cornices could be sensitive, and break back further than expected.   The chance for spontaneous running avalanche will increase as the day goes on, so backcountry travelers will want to stay out from under steep slopes in addition to avoiding any slopes with new drifts of wind blown snow.    Yesterday, explosive control work along the Park City ridgeline released a new snow slide 200 feet across and up to 5 feet deep.  It was on a steep, southeast facing slope that was heavily wind loaded.  Slides triggered in today’s new wind drifts have the potential to step sown into deeper weak layers.   

 

Over the past few days, shallow, weak snowpack areas in the Provo and Uinta mountains have had deep slides breaking near the ground in faceted snow.  Similar shallow snow pack areas also exist in the Salt Lake, Park City and Ogden mountains, though they are much smaller and more isolated.   

 

There are two other avalanche problems to keep in mind.  First, remember that many of the local ice climbs, including those in Provo Canyon, are in avalanche paths. Any time there is a chance for natural avalanche activity, many of the local ice climbs should be avoided.  Secondly, for the first time is years, a low elevation snowpack is starting to develop.  The approaching storm will be affecting the snow on slopes in and adjacent to the urban and mountains valleys, and we may need to start thinking of this low elevation terrain as avalanche terrain.   

 

Bottom Line (Salt Lake and Park City, Provo, and Ogden mountains):

The avalanche danger is CONSIDERABLE on recently wind-drifted slopes approaching 35 degrees and steeper.  Human triggered avalanches will be probable and natural avalanches possible.   Stay off of and out from under steep, wind drifted terrain.  With more wind and snow in the forecast, the avalanche danger may rise to HIGH later today or tonight. 

 

Uinta Mountains:  The Uintas have had some interesting activity.  For more information, click on western Uintas on the advisory page or phone 1-800-648-7433.

 

Mountain Weather:

A storm off the west coast will push a warm front across the area today.   There will be strong, southwesterly winds today and tonight, with ridge top averages in the 30 to 40 mph range, and gusts near 60 mph.  Snowfall should begin by late morning, with the heaviest rates this afternoon into this evening.  In the next 24 hours, 8 to 14” are expected in the Salt Lake and Park City mountains, 12 to 20 inches in the Ogden area mountains, and 6 to 10” in the Provo area mountains.  Highs today will be near 15 at 10,000’ and 20 at 8,000’.  Both the wind and snowfall should decrease by Tuesday morning as the storm system splits and moves out of the area.  Another storm is possible by late in the week.

 

 

For specific digital forecasts for selected mountain areas from the National Weather Service, click the links below or choose your own specific location at the National Weather Service Digital Forecast Page.

 

3-Day Table

3-Day Graph

7-Day Table

Ogden Mountains

Ogden Mountains

Ogden Mountains

SLC Mountains

SLC Mountains

SLC Mountains

Provo Mountains

Provo Mountains

Provo Mountains

 

 

General Information:

If the Wasatch Powderbird Guides are able to fly today, they will have one ship in American Fork.

 

If you are getting into the backcountry, please give us a call and let us know what you’re seeing, especially if you trigger an avalanche.  You can leave a message at 524-5304 or 1-800-662-4140.  Or you can e-mail an observation to uac@avalanche .org, or you can fax an observation to 801-524-6301.

 

The Friends of the Utah Avalanche Center is offering two 3-day avalanche workshops which are being held January 17-19 and February 14-16.  Information and sign-up sheets are available at the Black Diamond store (2092 E. 3900 S.; 278-0233).

 

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. 

 

Andrew McLean will update this advisory on Tuesday morning.

Thanks for calling.

_____________________________________________________________________________

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