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

7:30, Sunday January 27, 2008   

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Backcountry.com.

  We are issuing a Special Avalanche Advisory for midday today through Monday evening for the mountains of Northern Utah and the Western Uintas.  A powerful Pacific storm system will impact the region.  Strong winds and heavy snow will create widespread dangerous avalanche conditions in the backcountry.

Current Conditions:

Better batten down the hatches…  A strong Pacific storm system packing a double-shot of winter energy is upon us, and the National Weather Service has issued a Winter Storm Warning for the Northern Utah Mountains through Monday evening.  A southwest wind picked up intensity overnight, and it’s now cranking on the wind sensor at the CSI weather station on Logan Peak with hourly average speeds well into the 30 mph range and gusts of almost 60 mph.  It’s currently 21 degrees at 9400’ and 12 down in Logan City.  Expect snowfall to develop from the south this morning, becoming heavy at times throughout the day.  Strong southwest winds will continue through tonight, shifting around from the west near morning.

Avalanche Conditions:

An observer reports triggering a fairly substantial wind slab yesterday near a ridge top in the Southern Wellsville Range. As the party ascended a narrow ridge, they triggered shooting cracks and the sensitive slab released below them. The stiff wind slab on a north facing slope at around 7500’ measured about a foot deep and 80’ across. I triggered a similar wind slab avalanche on Thursday near the summit of Big Baldy in upper First Waterfall Hollow.  Earlier in the week we noted widespread frost or surface hoar crystals on the snow surface, and the development of weak sugary snow called facets in the upper layers.  Friday’s few inches of fresh snow nicely capped these weaknesses, and clearly wind slabs formed on weak surface snow in many areas.  We’ve received numerous reports of similar triggered wind slabs from across the mountains of Northern Utah.

Today you could find more of the same type of wind slab activity on many drifted slopes steeper than about 35 degrees. The problem today is most likely to be found at upper elevations, near ridge tops, and on slopes facing the northern half of the compass.  Slabs could be 1’to 2’ deep and may be quite sensitive, as many formed on weak surface snow.  Watch for smooth chalky looking or hollow sounding drifts on steep exposed slopes and cross-loaded slabs in and around terrain features like gully walls, rolls, sub-ridges, and cliff bands.

Rapid accumulation of heavy snow on top of existing weaknesses will likely cause a rapidly increasing danger on steep slopes.  This may become an issue by mid-afternoon as significant snowfall piles up and the danger becomes more widespread.  Heavy snowfall combined with strong winds leads to extensive loading over large areas, often depositing tons of snow onto slopes well off ridge lines.

Bottom Line:

There’s a CONSIDERABLE danger and you could probably trigger wind slab avalanches on many drifted slopes steeper than about 35 degrees in the backcountry.  This morning, you’ll find the most danger on steep upper elevation slopes facing the northern half of the compass.  Avalanche training and experience are essential for safe backcountry travel.

With heavy snowfall and strong winds in the forecast, expect the danger to rise significantly and become much more widespread throughout the day.  The danger is likely to rise to HIGH overnight, and significant natural avalanches are a good bet.

Mountain Weather:

The National Weather Service has issued a Winter Storm Warning through Monday evening.  The winds will begin to pick up significantly during the day.  Expect developing heavy snowfall and strong winds today in the prefrontal environment, and frontal passage sometime early Monday morning.  Expect 2+ feet of snowfall on favored slopes in the mountains by Monday evening….Another productive storm is forecast for Tuesday night into Wednesday.

General Announcements:

Check out photos of avalanches in the Logan Area on our images page.

Go to the Avalanche Encyclopedia if you have any questions about terms I use in the advisory

 I'm very interested to know what you're seeing out there.  Please e-mail observations to me at [email protected] or leave me a message at 755-3638, especially if you see or trigger an avalanche in the backcountry. We keep all observations confidential.

The second annual avalanche awareness ride is Saturday Feb. 2nd and we’d love to see all of you there!  Proceeds help to support snowmobile specific avalanche awareness projects. Details can be found at http://www.avarides.com/

This advisory will expire in 24 hours from the posting time.

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.