Wasatch Cache National Forest

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Avalanche advisory

ThursDAY, April 11, 2002   07:30 AM

 

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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 Thursday, April 11, 2002, and it’s 7:30 a.m.

 

Current Conditions:

Yesterday was a bit dreary with rain and snow in the mountains.  Areas above about 8,500’ picked up an inch of dense snow once the rain stopped.  Overnight under mostly cloudy skies, temperatures dipped to about 30 degrees at 7,000’ and into the mid 20’s at 10,000’.  The winds have been fairly calm below about 8,000’.  In upper elevation areas the winds have been from the west in 15 mph range.

 

I suspect we had another shallow refreeze last night.  Yesterday’s rain dampened the snow surface up to at least 9,500’.  The snow is crusted on most aspects at all elevations.  Above about 8,000’ the crusts are supportable on all but the shady upper elevation slopes.  Below about 7,000’ the snow mostly unsupportable.

 

Avalanche Conditions:

For better or worse it feels like spring out there.  In low and some mid elevation areas the snow is damp to the ground and yesterday’s rain made the surface snow soggy.  In thin snowpack areas the entire snowpack is damp and faceted, which makes for less than pleasant traveling and lots unsupportable snow.  Cool nights with shallow freezes are adding strength to the snowpack, but this strength is quickly eroded with daytime heating.  Traveling under steep rock slabs (like those in Broads Fork and Stairs Gulch) is not recommended and terrain traps at mid and low elevations should be avoided.

 

Above about 10,000’ the mid pack is still dry, but this warm weather is causing it to dampen quickly.  In these areas the snow remains mostly stable, but as the faceted snow becomes damp it will lose strength.  The deep slab instability that has plagued us since January has been quiet lately, but will again rear its ugly head as free water penetrates the buried weak layers.  The chances of triggering a deep slab avalanche will be isolated today, but consequences remain severe.

 

Bottom Line: 

Today the avalanche danger is generally LOW but there is a MODERATE danger of wet sluffs and slabs on steep slopes below about 9,000 feet, especially thin rocky areas.  If you are sinking into the snow past your boot tops avoid steep slopes and terrain traps such as cliffs and gullies.

 

(Ogden Area and Western Uinta Mountains)

Same as Salt Lake Mountains.  

 

(Provo Area Mountains)

Same as Salt Lake Mountains.

 

Mountain Weather:

A series of weak disturbances will move through northern Utah over the next two days.  Today skies will be mostly cloudy and light precipitation is possible.  The rain/snow line will be near 7,500’, but only trace accumulations are expected.  Temperatures will rise into the low 40’s at 8,000’ and upper 20’s at 10,000’.  Westerly winds will blow in the 10 to 20 mph range.  Tomorrow’s weather will be similar with slightly warmer temperatures.  A slightly stronger system is forecast for Sunday with an actual cold front expected on Monday.

 

General Information:

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.  We have a new avalanche and backcountry observation page that we’d like to encourage folks to try out.  It can be found on our home website at avalanche.org.  You can also 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. 

 

Tom Kimbrough will update this advisory by 7:30 Friday 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