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Logan area Avalanche Advisory

Wednesday January 2, 2008

Hello and good morning, this is Toby Weed of the Utah Avalanche Center with your Logan Area backcountry avalanche and mountain weather advisory.  Itís Wednesday January 2nd, and itís about 7:30 in the morning.  This advisory is brought to you in part by the Friends of the Utah Avalanche Center in Logan with help from Simmons Flexi-ski of Providence.

†††††††††††† Current Conditions:

Itís getting easier to travel through last weekendís stack of new snow, and folks are starting to get out into some steeper terrain without incident. Yesterday we found good floaty powder conditions on all aspects, but I expect to find some sun damage on south facing slopes today.I found out that itís still easy to get the sled stuck in deep snow if you get off the beaten path, especially at lower and mid elevations where, if you loose momentum, you can dig your track down into bottomless snow after floating on a midpack stiffness.Itís a balmy 30 degrees this morning at the Campbell Scientific weather station atop Logan Peak, and a south wind picked up overnight, now averaging close to 30 mph.Thereís 53 inches of total snow on the ground containing just under 10 inches of equivelent water at the Tony Grove Snotel, which is 68% of average for the date.

††††††††††† Avalanche Conditions:

Yesterdayís clearing pulled the cloudy veil off the upper elevations, and we could finally see evidence of the weekendís natural activity.While little activity was observed in the Southern Bear River and the Wellsville Ranges, I saw evidence of a fairly widespread cycle in the Central Bear River Range. Looks like most of the activity consisted of smallish wind slab avalanches, with one glaring exception on the popular Cornice Ridge.From a distance a very wide and deep crown is visible where a natural avalanche encompassing much of the main bowl ran during the windy weekend storm (pictures).Weíve received reports of several more human triggered avalanches in the Central Wasatch Range, including some large avalanches triggered by explosives at the ski areas and at least one triggered by a snowmobiler.

My biggest concern is the lingering possibility of deeper slab avalanches in some areas, which will be quite destructive and potentially deadly. The danger lies on slopes that didnít avalanche during the storm and are now hanging in a delicate balanceÖ.Trigger size appears to be the issue, with large triggers like explosives or snowmobiles still able to initiate large avalanches, while smaller triggers like backcountry skiers or snowboarders seemingly arenít heavy enough to do the trick. In most cases, your weight alone probably wonít be enough to trigger one of these deep dwelling monsters, but you might awaken one from a thin spot on the slab. Watch out for steep rocky areas and slopes with generally shallow snowcover. Pay attention to obvious signs of instability like recent avalanches on similar slopes, collapsing or woomphing noises, cracking, or hollow sounding snow, and be willing to reassess your route.

A south wind picked up overnight and will intensify over the next few days.Today you might find some fresh wind slabs that are sensitive to your weight. These chalky looking and hollow sounding drifts should be pretty obvious and as always, you should avoid them on steep slopes.

†††††††††††††† Bottom Line:

Today thereís a MODERATE danger on steep wind drifted slopes at mid and upper elevations in the backcountry.Dangerously large triggered hard slab avalanches are possible on some shady upper elevation slopes that had early season snowcover.Triggered wind slab avalanches are also possible in terrain exposed to drifting from southerly winds.Using good snow assessment and safe travel techniques will minimize todayís risks.

Mountain Weather:

The high pressure ridge will begin to move eastward out of the region today, and south winds will increase. The winds should scour the haze from Cache Valley.Looks like it could get quite blustery as the week progresses, with very windy conditions forecast for Friday and Saturday ahead of a promising looking storm later in the weekend.Some light snowfall is possible at upper elevations, with rain down low, before the weekend frontal passage.

General Information:

I will give a free avalanche awareness talk for teens and their families at the Stokes Nature Center in Logan Canyon at 9:00 on Saturday January 5th.

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.

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.