Wasatch-Cache National Forest  In partnership with:  Utah State Parks and Recreation, Friends of the Utah Avalanche Center-Logan, and Utah State University College of Natural Resources.

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Logan area Avalanche advisory

Thursday, December 29, 2005

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center in Logan.  It's Thursday December 29th at 8:30 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Patagonia.

Mountain Weather:

The next freight-car in the train of storms fed by warm Pacific moisture will roll into the region Friday afternoon, beginning as a moisture-laden warm front.  In advance of the system, the National Weather Service in Salt Lake has issued a Winter Storm Watch for all the mountains of northern Utah.  The trusty forecasters predict one to two feet of accumulation and strong southwest winds with this storm. Once again, warm temperatures will initially keep the snow/rain line at or above 8000' in elevation.  The storm is forecast to bring overcast skies by morning and light snow or rain in the afternoon.  Both snowfall and winds will intensify overnight Friday and last through late Saturday night with periods of heavy snowfall.  The cold front should arrive late Saturday and we'll have a break on Sunday.  The next storm, which looks like it could be the strongest in the series, will start to develop over the region on Monday.

Yesterday, rain fell for a time up to the highest elevations before switching over to snow around midnight. We did well water-wise, with the Tony Grove Snotel site boasting a storm total of 2" of water. Only about 1.2" of this fell in the form of about 10 inches of snow.  This time, temperatures cooled and the wind decreased as the snow started piling up.  Lighter snow fell on heavier snow, and unlike Monday's storm that dropped an inverted blanket of snow, this snowfall was "right side up."

Current Conditions:

 This type of snow is more pleasant to travel in, and today we found good riding conditions despite feeling the presence of rain-sodden mush underlying the powder. Snow conditions are best at higher elevations where there is significantly more new snow and less rain damage.  At lower elevations today, I would occasionally punch into moist, rotten-feeling snow.  If you step off your sled or boards, you easily sink all the way to the ground. 

Avalanche Conditions:

 It was quiet avalanche-wise in the backcountry today, with no avalanches reported or observed in the region.  But the water weight is certainly piling up on the snowpack and it won't be long at this rate before enough stacks up to start pealing things apart on some slopes.  Across the region, we've been monitoring buried weak layers that aren't really all that weak. This means that they'll hold a substantial load before failing.   In the coming days, as the storm train continues to roll over us, these not so weak weaknesses might be overloaded with enough weight to cause them to fail in the form of dangerous avalanches stepping into old snow.

Of more immediate concern for Friday are freshly formed wind-drift avalanches on steep exposed upper-elevation slopes and the potential for wet avalanches on steep lower and mid-elevation rain sodden or warmth moistened slopes.  You might be able to trigger avalanches on some slopes in the region fitting these descriptions. Tomorrow, we'll see both warming temperatures and increasing southwesterly winds, so chances are good that the danger on these slopes will increase somewhat and become more widespread before the end of the day.  This weekend, we may well see a general increase in avalanche activity across the northern Utah mountains.

Bottom Line:

On Friday, you'll find a MODERATE avalanche danger on steep wind-drifted slopes in the backcountry.  You could trigger avalanches above about 8000' on some slopes steeper than 35 degrees facing northwest through southeast with significant deposits of wind-drifted snow.  Rainfall or excessive warmth may also cause a MODERATE danger of wet avalanches on steep lower and mid-elevation slopes with saturated surface snow.

General Information: 

 For a list of our upcoming classes and awareness talks, go to our education page

Snow nerds, check out the new Snow Profiles page.

Please send backcountry observations to [email protected], especially if you see or trigger an avalanche in the backcountry.

  This advisory will expire on Friday night, but I will update it again on Saturday by 7:00 am.

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. 

National Weather Service - Salt Lake City - Snow.