Wasatch Cache National Forest

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               The Utah Avalanche Center Home page is: http://www.avalanche.org/~uac/

 

Avalanche advisory

Thursday, November 14, 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 Thursday, November 14, 2002,  and it’s about 7:30 am. 

 

We won’t have all our phone lines hooked up for a couple more days, so you may find it easier to access this advisory on the internet.

 

Current Conditions:

A mighty two inches of medium-density snow fell yesterday in foggy, gloomy weather and I’m expecting about the same thing today but with more wind today.  South facing slopes are sun crusted from Tuesday’s sun and there’s still a couple feet of nice snow on the shady aspects above about 9,000’ if you don’t mind hitting occasional rocks.

 

Avalanche Conditions:

It’s been three days since we’ve had any significant snow and this is the first morning that we haven’t heard about any natural or human triggered avalanches.  Normally, I would be tempted to lower the avalanche danger rating, but these are not normal conditions.   The first rule of avalanche forecasting is you ask yourself what kind of avalanche dragon you’re dealing with.  In this case, it’s not just depth hoar, but particularly large-grained, weak depth hoar, with a large load on top of it, which is notoriously persistent.  Yesterday, although I wasn’t feeling any collapsing snow like I was a couple days ago, I still had a hard time isolating columns in my snowpit tests and there’s still a super-critical temperature gradient across the weak-layer.  That’s avalanche-speak that it’s taking it’s sweet time to stabilize.    

 

Another thing that scares me is that only some of the slopes have avalanched and there are just as many that have not, still waiting for the right trigger.  These kinds of avalanches are kind of like a bar room brawl, no matter how much tension there is, you need to give someone a thump to get things going.  It’s also tricky because as the slab gains strength, yes, it’s harder to trigger, but if you do, it means that the crack forms that much farther above you and there’s that much more snow on top of you when you’re buried.  All the old pro’s I know are refusing to jump into steep, shady terrain. 

 

Finally, with stronger northwest ridgetop winds today, you will probably find some fresh wind slabs in upper elevation, wind exposed terrain, that you can trigger easily, but they will likely be mostly shallow.

 

Bottom Line:

The avalanche danger is still  CONSIDERABLE today on northeast, north and northwest facing slopes, approaching 35 degrees or steeper, above about 9,000’, or on steep slopes with recent wind drifts.  Considerable means dangerous human triggered slides are probable.  There’s a MODERATE danger on those same slopes between 30 and 35 degrees and on steep east and west facing slopes.  LOW danger terrain includes slopes of about 30 degrees of less, well out from under avalanche terrain, or on southwest through southeast facing slopes or elevations below about 9,000’.  

 

Mountain Weather:

Today should be another day kind of like yesterday with light snow showers—perhaps 1-3 inches, but ridgetop winds should be moderate to strong, 20-40 mph from the northwest with ridgetop temperatures 20-25 and 8,000’ temperatures around 30.  Things should be clearing out Friday and we’re headed into a warm, sunny weekend.  Next chance for snow would be maybe another week.

 

General Information:

I will teach an avalanche class tonight at 7pm at the Black Diamond Retail store. For a complete list of evening talks and multi-day classes, visit www.avalanche.org and click on Salt Lake and then Education. 

 

To report backcountry snow and avalanche conditions, especially if you observe or trigger an avalanche, call (801) 524-5304 or 1-800-662-4140.  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 on Friday 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