Wasatch Cache National Forest

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Avalanche advisory

FRIday, MARCH 29, 2002 07:30 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 Friday, March 29, 2002, and it’s 7:30 a.m.

 

Current Conditions:

Overnight lows were near 20 above 9,000 feet, around 30 at 7,000.  Some 6,000 foot temperatures were above freezing but with only some high clouds last night, I expect a decent re-freeze of the snow pack at all elevations.  Winds are strong, hitting 20 to 30 from the west northwest along the ridges, with the highest peaks getting up into the forties with gusts to 60, but there isn’t much loose snow to blow around.  Many backcountry slopes have crusts of varying thickness with a little settled powder on upper elevation shaded and wind sheltered slopes.  There are some supportable crusts developing on southerly facing slopes at around seven to eight thousand feet.  You need to start early; yesterday the crusts were becoming breakable by 10:00 or 11:00 am.  We will be doing 6:00 am corn reports for the rest of the season on the (801) 364-1581 phone line.

 

Avalanche Conditions:

There was no avalanche activity reported yesterday, for the first time in a couple of weeks.  The present weather pattern of warm days and cool nights is probably partially stabilizing the layers that have been causing this recent extraordinary series of deep breaking avalanches.  But with the last reported deep slides releasing only last Tuesday, I’m not quite ready to bet my life on it.  The weak layers are still down there and stability tests indicate that they are still sensitive.  The most recent slides were in Mineral and Silver Forks in Big Cottonwood and Hogum in Little Cottonwood.  These slides broke 3 to 4 feet deep on north through southeast facing slopes between about 9 and 10 thousand feet elevation.  This is the Silver Fork avalanche.  Another huge avalanche released in Black Rock Canyon of the Oquirrh Mountains and is visible from I-80.  In addition to the deep avalanches, there have been numerous wet surface slides.  Along with all the big avalanches we have also received reports of folks riding steep lines without incident.  This type of pattern makes avalanche decisions difficult.  Although there are many safe places to travel, there remains the possibility of triggering a very large and deadly avalanche.  With supportable crusts developing on sunny slopes, there is good reason to limit travel to the sunny side, which is mostly stable until daytime warming reduces the snow to wet slop.

 

Strong northwest winds over the past three days have produced some shallow but sensitive drifts along the upper elevation ridges.  Be alert for fresh drifts on steep wind exposed slopes above about 9,000 feet.  Although the cool northwest winds will slow the heating, there will probably be some wet slides today on sun baked slopes. Temperatures remained cool enough yesterday that there wasn’t much wet slide activity and we expect similar weather conditions today but if the snow gets wet and mushy, it is time to get off of and out from underneath steep slopes. 

 

Bottom Line: 

The avalanche danger is MODERATE on northwest, north and east facing slopes steeper than about 35 degrees.  On southerly facing slopes the danger is generally LOW this morning but will rise to MODERATE with daytime heating.  There is also a MODERATE danger of triggering a deep, very dangerous hard slab avalanche in steep terrain, especially in thinner snowpack areas. 

 

(Ogden Area and Western Uinta Mountains)

Same as Salt Lake Mountains.  

 

(Provo Area Mountains)

Same as Salt Lake Mountains.

 

Mountain Weather:

A cool northwest flow will be over Utah through the weekend.  Skies will be mostly sunny but with occasional high clouds.  Highs today will be around 40 degrees at 8,000 feet and in the thirties at 10,000.  Winds will be 20 to 30 mph from the northwest over the high peaks and ridges.  With partly clear skies and overnight lows in the twenties, the snowpack should re-freeze tonight.  This same weather pattern looks like it will hold right through the weekend. 

 

General Information:

Wasatch Powderbird Guides be flying today in the Mill Canyon area of American Fork.  For more information call 521-6040 ext. 5280.

 

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 [email protected], or you can fax an observation 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. 

 

Ethan Green will update this advisory by 7:30 on Saturday 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