Wasatch Cache National Forest

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Avalanche advisory

saturDAY,  FEBRUARY 23, 2002  3:00 PM

 

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Good afternoon, this is Bruce Tremper with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  Today is Saturday, February 23, 2002, and it’s 3:30 p.m.

 

Current Conditions:

Overnight and this morning, 8,000’ temperatures rose to nearly 50 degrees and ridge top temperatures were near freezing with 30 mph winds, gusting to 60 out of the south and southwest.   This afternoon, however, temperatures are beginning to fall along with the wind speeds.  Yesterday and this morning, the snow was wet or damp almost all aspects and elevations and the only dry snow left is above about 9,000’ on north facing slopes.

 

Avalanche Conditions:

The unseasonably warm weather produced quite a bit of wet point releases and some wet slabs on steep slopes, especially near rock bands yesterday and especially on the more southerly facing slopes.  However, with colder temperatures on the way, the wet snow will freeze up solid as a rock.  Even though the strong winds blew, there wasn’t much snow to blow around so only shallow wind slabs formed in very localized areas near the ridge tops.  As we’ve been mentioning these past several days, we still have lots of very weak, faceted snow in thinner snowpack areas such as lower and mid elevations in the Salt Lake area mountains and in most places in the Provo and Uinta mountains.  Much of the time you are just wallowing in this almost bottomless depth hoar and it obviously won’t support much additional weight.  For instance, yesterday in the western Uinta Mountains, a snowmobiler triggered a hard slab on top of depth hoar and was caught on a northeast facing slope on Bald Mountain that broke out 4-6 feet deep and 200 feet wide around 10,000’ in elevation.  I suspect that the colder temperatures tomorrow will make it harder to trigger these deep, scary avalanches.

 

With the storm coming in tonight and on Sunday, one problem will be the new snow sliding on the old, hard, slick bed surfaces.  Luckily, or perhaps unluckily, depending on your perspective, we probably won’t have much new snow to deal with.  If you’re getting out on Sunday, as usual, you should avoid steep slopes with recent deposits of wind drifted snow.  The other problem is triggering a hard slab that overlies the weak, sugary depth hoar, as I’ve said.

 

Bottom Line: 

The danger of human triggered avalanches is MODERATE on any slope steeper than about 35 degrees with recent wind drifts and also MODERATE on all slopes where slabs are underlain by weak, faceted snow especially at mid and lower elevations.   (considerable in the Provo and Uinta mountains.)

                                                                                                                      

(Provo Area Mountains and Western Uinta Mountains)

 

In areas that have had a thin snowpack most of the winter the snow is sugary and weak with recent wind deposits on top.  The danger of human triggered avalanches is CONSIDERABLE on slopes in the Provo and Western Uinta Mountains, especially where wind loaded. 

 

(Ogden Area Mountains)

Same as Salt Lake Area Mountains

 

Mountain Weather:

The cold front arriving tonight is a bit of a strange beast in that the cold front should arrive around sun down, but the precipitation will wait until later tonight to arrive.  Even when it does, it doesn’t have much moisture with it and it looks like it will only produce light snow showers with storm totals about 2-5 inches—and for you Olympic visitors who might think that this kind of weather is normal, you should know that this is quite a small and anticlimactic storm for the Wasatch Range.  Snow should begin tonight, perhaps 8 pm and continue off and on tonight and be scattered snow showers on Sunday.  Ridge top temperatures will dramatically cool down to 15 degrees on Sunday with 8,000’ temperatures cooling down to the mid 20’s.  Ridgetop winds will back off to around 20-25 mph and turn westerly and be west-northwest on Sunday. 

 

As for the extended forecast, skies should clear on Monday and remain cool with another weak storm on Tuesday night into Wednesday, then perhaps another one next weekend.

 

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.  Or you can e-mail an observation to [email protected] .org, or you can fax an observation to 801-524-6301.

 

We have a new icon-based, short advisory posted each day at www.avalanche.org.  We would appreciate any feedback on this new product.

 

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. 

 

Evelyn Lees will update this advisory by 7:30 Sunday 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