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

 

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Avalanche advisory

Saturday, December 14, 2002

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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 Saturday, December 14, 2002, and itís 7:30 in the morning.

 

Current Conditions:

I must say Iím impressed with the present state of the long and mid range weather forecasting.Some of the computer models saw tomorrowís change in our weather pattern two weeks ago.The computers may not yet get the details just right every time but they are getting the general picture right most of the time and often well in advance of the event.

 

This should be the transition day with winds picking up from the south and southwest. Mountain temperatures are in the mid twenties this morning, with ridge top winds 10 to 20 mph with gusts to 30.

 

Snow totals from the mid week snow event were around 2 to 5 inches but a short period of moisture and rain at the end of the storm capped the new snow with a thin crust.This crust has been observed in the Logan, Salt Lake and Park City Mountains, from as low as 7,600í to the tops of the peaks and on most aspects.I canít say this combination improved the backcountry turning conditions.

 

Avalanche Conditions:

As we learned in our basic classes to have an avalanche you need a slab and a weak layer.There may not be a slab yet this morning but, man, do we have weak layers.Itís like a whole chapter out of the avalanche handbook.Thereís depth hoar, surface hoar, mid pack facets, near surface facets, crust and facet sandwiches; you name it, itís out there.Now to top it all off there is this thin crust from the Wednesday rain that has surface hoar on top and a faceted layer underneath.The weak layers are most obvious on northerly facing shady slopes but east and west facing, even around to the southeast and southwest have weak layers associated with crusts.Some of these slopes may be especially sensitive to increasing loads with the crusts providing good bed surfaces.

 

Even before it starts snowing sometime tonight the increasing winds this afternoon will cause the avalanche danger to begin to rise.

 

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

The avalanche danger is generally LOW this morning but will rise to MODERATE with human triggered avalanches becoming possible this afternoon in steep wind exposed terrain.The danger will become more widespread tonight and Sunday and may increase as snowfall accumulates.

 

Mountain Weather:

Clouds and wind will increase today.High temperatures will be near 40 at 8,000 feet and in the thirties at 10,000.Ridge top wind speeds may reach the 25 to 35 range with gusts over 50 mph this afternoon and tonight.Snowfall should begin after midnight and continue into Sunday afternoon with storm totals of around 4 to 8 inches.Another storm is scheduled to arrive Monday afternoon, possibly continuing into Wednesday.

 

General Information:

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.

 

Ethan Green will update this advisory by 7:30 on Sunday morning.

 

Thanks for calling!

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National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings:

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