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Logan area Avalanche advisory

Tuesday March 14, 2006

Hello, this is Toby Weed of the Forest Service Utah Avalanche Center with your Logan area backcountry avalanche and mountain weather advisory.  It's Tuesday March 14th at 9:00 pm.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Backcountry Access Inc.

Mountain Weather:

The National Weather Service in Salt Lake City issued a Snow and Blowing Snow Advisory for the region until noon Wednesday.  Strong south winds will continue at upper elevations through the evening.  Snowfall will intensify overnight, and the winds will gradually diminish and turn northwesterly on Wednesday.  The fast-moving storm will be gone by afternoon, and we'll get a short-lived break on Thursday. A juicy storm will move over the region for the weekend, and more spring storminess looks to be on track for next week.

Current Conditions:

You can still find nice powder conditions on lots of slopes, but Wednesday might well be a good day to choose low angled, or at least generally sheltered slopes to play on.   We could pick up a decent shot of powder tonight and tomorrow morning. Slightly less than a foot of snowfall and west winds are forecast for upper elevations. I found great powder conditions today at upper elevations on all slopes facing the northern half of the compass.  Lower elevations offer nice shallow powder or dust-on-crust conditions on shady slopes, with most slopes under about 7500' sporting a supportable melt-freeze crust under a few inches of newer snow. Temperatures warmed up today, and surface sun-crusts developed this afternoon on south facing slopes.

Snow and Avalanche Conditions:

In comparison to much more impressive snow amounts in the Central Wasatch, we've only picked up 5 or 6 inches of snowfall at upper elevations in the region in the past few days. The Tony Grove Snotel site reported 4/10ths of an inch of water in the last 72 hours compared to nearly 2 inches at Snowbird.  With generally lower elevation terrain and therefore less exposure to upper elevation winds, there is a bit less avalanche danger in the mountains around Logan than in those to our south.  Even so, incessant southerly winds built sensitive drifts today with the fresh snow in exposed areas and at high elevations. This morning, big plumes of air-borne powder streamed from the high peaks surrounding Cache Valley.  Clearly, the strong south winds built stiff drifts or wind slabs on lee slopes and near terrain features like gullies, rock outcrops, and sub-ridges.  More intense drifting occurred in areas most affected by southerly winds like the Logan Peak Area, the mountains near Mantua, and the Wellsville Range.  You'll find the most extensive wind slab formation (and the most danger) on upper elevation slopes facing the northern half of the compass, but cross-loading and terrain channeling also built some suspect drifts at mid-elevations and on other slopes.   Drifting appeared confined to upper elevation ridges in the more sheltered central and northern Bear River Mountains, but this afternoon I easily triggered shooting cracks in a fresh ridge-top slab on an upper elevation northeast facing slope in upper White Pine Canyon .  Shooting cracks indicate potential for avalanches, and in this case, I would have triggered an avalanche had I been on a steeper slope.  I noticed only one recent natural wind-drift avalanche and many small loose snow avalanches in the thousands of acres of terrain that I scanned with the binocs from a good vantage-point.  Most of Wednesday's wind slab avalanches will probably only involve fresh wind-drifted snow, but some could step down to a buried weak layer consisting of sugary or faceted snow.  The weakest layer I found today was on an upper elevation east facing slope, around a foot below the surface, just beneath a somewhat fragile sun-crust formed in the first week in March.

With cold temperatures and cloud-cover in the forecast, I don't think we'll have much of a problem with wet avalanches on Wednesday.  But, the seasonally high sun-angle causes sheltered slopes to heat up and get sloppy very quickly, and we are likely to see an increasing danger of wet new snow avalanches on steep slopes if the sun gets out for a while on Thursday .  I noticed a few small natural wet point-release avalanches early this afternoon on south facing mid-elevation slopes.

Bottom Line:

There's a MODERATE  danger and avalanches are possible on some wind-drifted slopes steeper than about 35 degrees in the backcountry.  A CONSIDERABLE danger exists in some exposed high elevation areas, where you could trigger avalanches on many steep wind-drifted slopes and some natural wind slab avalanches might occur.

General Information: 

If you're confused by some of our avalanche terms check out the cool new Avalanche Encyclopedia

For a list of recent avalanches in  the regional backcountry go to Avalanche List.  Snow nerds, check out the new Snow Profiles page.  Check out our Images Page for pictures of recent local avalanches.

Please send backcountry observations to [email protected] or leave a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We really want to hear from you, even if you think your observation is unimportant.    The information you provide may save lives...

 This advisory will expire on Wednesday night.  I will update it again on Thursday night.

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.