Wasatch Cache National Forest
In partnership with: Utah Division of State Parks and Recreation, The Friends of the Utah Avalanche Center, Utah Department of Emergency Services and Homeland Security and Salt Lake County.

“keeping you on top”

AVALANCHE ADVISORY

Sunday, December 02, 2007  7:30 am
Good morning, this is Drew Hardesty with the Forest Service Utah Avalanche Center with your backcountry avalanche and mountain weather advisory.  Today is Sunday, December 02, 2007 and it’s about 7:30 am.

 

Current Conditions:

When it was all said and done, the Provo area mountains, the upper reaches of Big and Little Cottonwood and the Park City ridgeline pulled in about a foot of snow.  The Ogden area mountains, just at the northern reach of this southerly track system, raked in about 6”.  Densities averaged 8%, and came in on top of Wednesday’s rapidly settling 6-8” of 5% fluff.  Skies are starting to break as the remnant pieces of the storm moves off to the east.  Mountain temperatures dropped to the single digits and low teens and the westerly winds, while gusty into the 30’s overnight, are now less than 15mph at most locations. 

 

Riding conditions are greatly improved, though you’ll need to look for terrain above, say, 9500’-10,000’ on the northerly aspects to find enough coverage.  Snowmachines will want to remain on the snow-packed roads. 

 

Avalanche Discussion:

There were a number of close calls and human triggered avalanches in the backcountry yesterday.  Let’s go to the checklist:  old weak, pre-existing snow – check; a foot of heavier new snow – check; collapsing and whoomphing within the snowpack – check; long running shooting cracks – check; pockety naturals within the new snow – check, check, check.  Add a starved Wasatch backcountry community chomping at the bit and it all adds up. It seemed that human triggered avalanches, and collapsing and cracking were the rule, rather than the exception.  We heard of three very close calls in the upper reaches of Big and Little Cottonwood with two individuals taking rides in separate incidents.  These incidents occurred on Patsy Marley in upper Little Cottonwood, and in upper Days and Silver Fork of upper Big Cottonwood.  Terrain variables were all the same: above about 9800’, northerly aspects, slopes steeper than 35 and approaching 40 degrees, and areas that had a weak pre-existing snowpack.  Photos from yesterday’s activity can be found on our photos page here.  Pit data and fracture line profiles can be found here.  Folks willing to stick their necks out in similar terrain today can expect similar results.

 

The pockety natural activity will have settled out, but the persistent slab problem will be much the same.  Collapsing of the facets, depth hoar and facet/crust sandwiches will still alert the unwary traveler to danger, as remotely triggered slides remain a likely scenario.  Simple ski pole-probe tests will allow you to sniff out the weak sugary faceted snow underneath, and run-of-the-mill stability tests ought to provide damning evidence as well.  Best to stay off of and, due to the nature of remotely triggered slides, out from underneath the suspect terrain.  Look for gentler slopes in the 30 degree range : much safer and you’re less likely to punch into the buried rocks and stumps.

 

Lastly, with so many of us and so few places to go, I’d encourage good backcountry etiquette.  Jumping in a slope above others is tantamount to homicide.  Be polite.

 

Bottom Line:

Salt Lake and Provo area mountains: The avalanche danger is MODERATE on northwest, north and northeast facing slopes steeper than about 35 degrees above about 9,000’ in elevation. Human triggered avalanches, including the potential to trigger slides from a distance, remain very possible.  If the westerly winds kick in this afternoon, as advertised by one weather model, the danger will rise accordingly.  Watch for changing conditions.

 

Ogden and Park City area mountains: The danger is generally LOW with so little pre-existing snow.

 

Mountain Weather: 

A shortwave ridge will build over the next couple of days, providing clearing skies and rapidly warming temps.  8000’ and 10,000’ temps will rise into the mid-twenties and mid-teens as winds remain on hold until the afternoon.  Confidence levels are shaky on the timing and distribution, but the central Wasatch-north may see speeds into the 30-35mph range by dinnertime.  A weak system brushes through Tuesday night, with another system on tap for Thursday.  Looking from a week out, next weekend might bring another warm, moist storm on a southerly storm track. 

 

Announcements:

 

For an avalanche education class listing, click HERE.  

 

If you want to get this avalanche advisory e-mailed to you daily click HERE.

 

The UAC has job openings.  Click HERE for info.

 

We are in the office most days.  You can reach us by calling 524 5304 or e-mail us at [email protected].  Keep in mind it may take a few days if you are looking for a return message.

 

UDOT highway avalanche control work info can be found HERE or by calling (801) 975-4838.

Our statewide tollfree line is 1-888-999-4019 (early morning, option 8).

For our classic text advisory click HERE.

If you are getting out and see anything we ought to know about please let us know.  You can leave a message at (801) 524-5304 or 1-800-662-4140, or email us at [email protected]. (Fax 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 Monday morning.