Wasatch Cache National Forest

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Avalanche advisory

TUESDAY, MARCH 19, 2002 07:30 AM



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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, March 19, 2002, and it’s 7:30 a.m.


Current Conditions:

With clear skies overnight, ridge top temperatures are around 5 degrees this morning and winds have picked up and it’s blowing around 20-25 mph from the west.  There’s about a foot of delightful powder from Saturday night with some relatively thin sun crusts on the surface on south facing slopes.


Avalanche Conditions:

Yesterday a group of backcountry skiers triggered a very large slide on what is known as the “Cabin Run” on the north side of Gobbler’s Knob in Mill Creek Canyon.  This incident conveniently tells the entire story of our snowpack all in one package.  They were breaking a climbing trail up on a gentle spur ridge and triggered a 2000 foot wide, 4 foot deep avalanche from the flank of the avalanche while they were on a 32-33 degree slope.  None of them were caught because they knew what they were doing and were following good route finding procedures by staying on the ridge instead of getting under the steeper slopes.  The upper part of the slide slid on a 38 degree slope and it descended into Pole Canyon about 1000 vertical feet and snapped off some trees. 


The kind of places where people have been triggering avalanches these past few days are usually thin snowpack areas—usually less than about 4 feet deep—that are underlain by weak, depth hoar.  Although many of these slopes slid during last week’s storm many are still hanging in the balance, just waiting for a trigger.  This kind of instability is notorious for being frustratingly persistent, not giving any of the classic signs of instability such as collapsing or cracking.  They are difficult to detect with snowpits.  They can often have a number of other tracks on them.  They break deep and large.  Once it goes, it takes out the entire slope and most of them are unsurvivable.  In other words, it’s your basic nightmare.  The bottom line is that you should continue to be patient and avoid any slope approaching 35 degrees or steeper that did not slide during the last storm.  If you insist on getting onto something steep, the hot tip is to go to one of the many slopes that did slide big in the last storm because they are now very safe and they are covered with about a foot of nice powder, which smoothes out the old debris.  For a list of what has slid during the past week, call our more detailed report at 364-1591.  Finally, today as the wind increases, watch out for the usual round of wind slabs that form on lee, wind exposed terrain.


Bottom Line: 

So what danger rating do you call this kind of instability?  In this case, the usual definitions don’t work very well.  Yes, there are only localized places where you can still trigger an avalanche, which we would call a MODERATE danger but if you do trigger one, it will be very large and probably unsurviable.  Traditionally thinner snowpack areas, such as on the periphery of the Cottonwood Canyons, the Unita Mountains and the Provo area mountains have a CONSIDERABLE danger.


(Provo Area Mountains)

Provo Area Mountains have very weak snowpack and received more snow during the last storm.  As a result the avalanche danger in the Provo Mountains is CONSIDERABLE.   Very large and dangerous human triggered avalanches are possible. 


(Western Uinta Mountains)

The avalanche danger in the Western Uintas is CONSIDERABLE.  Very large and dangerous human triggered avalanches are possible. 


(Ogden Area Mountains)



Mountain Weather:

Today we have some mid and high level moisture crossing Utah, which should bring partly to mostly cloudy skies and light snow flurries without much accumulation.  Ridge top winds will blow 25 mph from the west with ridge top temperatures in the single digits this morning rising to around 19 by later in the day.  8,000’ temperatures will be in the mid 20’s with an over night low in the mid teens.  Tomorrow, we should have clearing skies, and warming temperatures as a high pressure ridge builds over us.  This should bring spring like conditions to the mountains through Friday.  Then it looks like another storm for the weekend. 


General Information:

Wasatch Powderbird Guides will be flying in Cardiff, Days and Silver Fork today with a home run in Grizzly Gulch.  For more information call 521-6040 ext. 5280.


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], or you can 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. 


I will update this advisory by 7:30 on Wednesday 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: