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

Tuesday, December 17, 2002

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Good Morning.  This is Bruce Tremper with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  Today is Tuesday, December 17, 2002, and it’s 7:30 in the morning.


Current Conditions:

Well, it’s about time.  We’re finally getting some significant snow in the mountains.  Places favored by a south to southwest flow, such as Timpanogos, Ben Lomond Peak and Snowbasin, have picked up 15 inches of new snow and the Cottonwood Canyons and Uinta Mountains are around 6 inches of new since yesterday afternoon.  Winds have turned westerly and have decreased to around 20 mph with ridge top temperatures around 15 degrees.  Remember that all the ski areas will be close to uphill traffic this morning while they are doing avalanche control.


Avalanche Conditions:

Yesterday the winds were nuking 30-40 mph with gusts to 60, which created localized areas of very sensitive wind slabs.  As the snow piles up, I expect the weight of new snow and wind blown snow will easily over load the extremely weak, pre-existing, faceted snow and avalanche activity will become more widespread.  I have issued a “special avalanche bulletin” this morning and I expect this will become a full-blown avalanche warning by later today or Wednesday.  


Before this latest new snow, the sun melted most of the south facing slopes down to bare ground, where the new snow will be anchored fairly well by the rocks and bushes.  It’s a whole different story, however, on the shaded slopes, such as northwest, north, northeast and east facing slopes where the pre-existing snow has rotted out to become extremely weak depth hoar, which won’t support much additional weight.  Remember that these kinds of conditions tend to force people onto the shady slopes because they are the only ones that have a base, and those are exactly the slopes that are most dangerous.  Today you need to watch your slope angles very carefully and stay on gentler slopes.


Bottom Line (SLC, Park City Area Mountains):

The avalanche danger is CONSIDERABLE today on all slopes above 8,500’ which face northwest, north, northeast and east approaching 35 degrees and steeper.   With continued snow, I expect the danger to rise to HIGH later today or on Wednesday.   On all southwest, south and southeast facing slopes the danger is MODERATE.


Bottom Line (Ogden and Provo Area Mountains)

The avalanche danger is HIGH today on all slopes above 8,500’ which face northwest, north, northeast and east approaching 35 degrees and steeper.  On all southwest, south and southeast facing slopes and low elevation slopes without pre-existing snow the danger is MODERATE.




Mountain Weather:

A beautiful-looking, wide, trough over the western U.S. is bringing pulses of snow into us from the west.  The latest pulse should end this morning, and we should get the next one this afternoon and another one probably tonight.  This westerly flow tends to lay down relatively even snow amounts throughout the Wasatch Range and I’m expecting another 5-8 inches of snow this afternoon and probably that much again tonight.  Ridge top winds should continue to blow 20 mph from the west with ridge top temperatures around 15 degrees.  8,000’ temperatures should be around 28 degrees with an overnight low around 16.


Snow on an unstable westerly flow should continue through Wednesday with ridge top winds switching to the northwest by about mid day Wednesday and temperatures should drop into the single digits on the ridge tops.  For the longer range, after a break on Thursday, we should be back to a weaker storm on Friday and Saturday.


General Information:

The Friends of the Utah Avalanche Center will offer an intensive 3-day avalanche class January 18-20.  You can sign up at the Black Diamond Retail Store or call them at 278-0233.


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.


Evelyn Lees will update this advisory by 7:30 on Wednesday morning.


Thanks for calling!




National Weather Service - Salt Lake City - Snow.

For an explanation of avalanche danger ratings: