Wasatch Cache National Forest

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Avalanche advisory

Wednesday,  FEBRUARY 27, 2002  7:30 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 Wednesday, February 27, 2002, and it’s 7:30 a.m.

 

Current Conditions:

Overnight under mostly clear skies westerly winds blew in the 40 mph range with gusts in the 50’s and 60’s.  The strong winds seem to be confined to the highest ridgelines.  Mid elevation weather stations show overnight winds in the 20 mph range.  Low temperatures last night were below 10 degrees at both 8,000’ and 10,000’. 

 

Yesterday’s sunshine was enough to put a crust on many southerly aspects.  Elsewhere you can find anything from soft settled snow to variable wind slabs and old hard scoured surfaces. 

 

Avalanche Conditions:

The strong westerly winds over the last three days with new snow on Sunday and Monday built wind slabs that produced both natural and human triggered avalanche activity.  These avalanches occurred mostly on north through east aspects above 8,500’.  The winds were strong enough to load slopes well below the ridgelines and cross load the sides of gullies or subridges.  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 8,000’. 

 

Last night the winds were again quite strong and from the west and northwest.  So today be on the lookout for fresh wind deposits.  There is plenty of weak snow out there so in many places new wind drifts will be sensitive to the weight of a person.  In some places the snow is weak down to the ground so any avalanche in the new snow has the potential to break down into deeper layers.  Our snowpack is like a patchwork quilt with areas of strong and weak snow intermixed throughout the range.  The stability in the Wasatch Mountains is

highly variable and winter travelers need to evaluate each slope before crossing it.   

 

In areas sheltered from the sun and wind the loose snow easily slides off the old snow surface.  Remember that even small sluffs can be dangerous if they push you off a cliff or into a gulley.

  

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 weak faceted snow.  Suspect areas for this would be upper elevation steep rocky chutes, areas that have slid earlier in the year or 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 loaded. 

 

(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 low-pressure trough moving through Central Idaho and into Wyoming will bring clearing skies and strong winds to the Wasatch Mountains today.  Temperatures will rise to near 30 degrees at 8,000’ and into the mid to upper teens at 10,000’.  Northwest winds will be in the 30 to 40 mph range this morning and decreasing into the 20 to 30 mph range this afternoon.  A stronger system will bring cold temperatures and snow beginning Thursday afternoon.  Moderate snow accumulations are expected by Friday morning with temperatures warming into the weekend.

 

General Information:

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

 

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] .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. 

 

Tom Kimbrough will update this advisory by 7:30 Thursday 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