Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed for
Tuesday, December 18, 2012

There is a CONSIDERABLE (or level 3) danger in the backcountry, and triggered wind slab avalanches are likely on steep drifted upper and mid elevation slopes. There are also areas with poor snow structure and increasing potential for larger, more dangerous deep slab avalanches, failing on buried persistent weak layers, up to around 3-feet-deep. The danger on drifted north through east facing slopes at upper elevations is HIGH (level 4). Avalanches in some areas might be triggered remotely from a distance or below. Natural avalanches likely occurred overnight, but are still possible today. Avoid and stay out from under steep slopes with significant accumulations of drifted new snow. Evaluate the snow and terrain carefully , and make conservative decisions regarding your route selection. ..

Low
Moderate
Considerable
High
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Avalanche Warning
 STRONG WIND AND NEW SNOW ON TOP OF WEAK PRE-EXISTING SNOW HAVE CREATED THE POTENTIAL FOR DANGEROUS, HUMAN TRIGGERED AVALANCHES.
Weather and Snow

The Tony Grove Snotel reports another foot-plus of accumulation yesterday and overnight containing 1.6 inches of water equivalent. There's 54 inches of total snow, 104% of average for the date, and it's 11 degrees at 8400' this morning. Southwest winds gusted to 67 mph yesterday, but they've shifted around from the northwest and diminished into the single digits overnight at Campbell Scientific's 9700' mountain top Logan Peak weather station, and it's a bone chilling 3 degrees. Yesterday's snow was inverted, just a bit heavier on top, and you sunk deeply into the lighter stuff from Sunday. Slow motion turning conditions meant that you needed to be on a pretty steep pitch to gain enough momentum. This may lure you into slopes steep enough to avalanche. Trail breaking was difficult and time consuming because you sink into the new snow so deeply.

Recent Avalanches

No avalanches were reported recently in the Logan Area, but I'm betting on at least a few naturals overnight last night, given the intensity of yesterday's storm.

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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description

Triggered wind slab and storm snow avalanches are likely today. Fresh wind slabs exist on the lee sides of major ridgelines and in and around terrain features like gullies, scoops, sub-ridges, cliff bands, and rock outcroppings.. We found a poor bond between yesterday's heavy snow and Sunday's lighter powder, with extensive cracking and failures with isolation in hand pit tests.. Although I expect this weakness to heal fairly quickly, soft slab avalanches including the new snow are still likely today. Winds slabs consisting of stiffer drifted snow will appear smooth, rounded, and maybe chalky, and they often sound hollow or drum-like when you walk around on them. You should continue to avoid and stay out from under steep drifted slopes.

Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description

There are areas with poor snow structure where you could trigger dangerous deep slab avalanches releasing on buried persistent weak layers. I've been observing weak layers consisting of small sugary grains called faceted snow across the zone, with the weakest in areas with relatively shallow snow. The rapid load from yesterday's storm could cause these layers to become activated, and dangerous deep slab avalanches, up to around 3-feet-deep will become increasingly possible...The most suspect slopes are at upper elevations and facing north through east, but significant loading might have caused the danger to become more widespread. Pay close attention to red flags like audible collapsing and cracking, be willing to reevaluate or turn back, and avoid steep slopes with significant accumulations of drifted snow.

Additional Information

It'll stay mostly cloudy today with high temperatures in the lower teens and a light northwest breeze. Temperatures may well drop below zero tonight in the mountains, and the breeze will be from the north. We could see a bit of sunshine tomorrow and it'll stay cold , with high temperatures hopefully rising above the single digits as a short-lived high pressure ridge gains control of the weather pattern. A moist southwest flow will reestablish over the region late in the week and the next Pacific storm system looks to be on track for Sunday and Monday...

Check out the Logan Mountain Weather page...

General Announcements

Beaver Mountain now has great coverage and plans to open the lifts for the season on Thursday December 20.

Discount lift tickets are in and it would be a good day for lift serviced riding! Go to http://www.backcountry.com/utah-avalanche-center to get tickets from our partners at Alta, Beaver Mountain, Brighton, Canyons, Deer Valley, Park City, Powder Mountain, Snowbasin, Snowbird, Solitude, Sundance, and Wolf Mountain. All proceeds benefit the Utah Avalanche Center.

Remember your information can save lives. If you see or trigger an avalanche in the backcountry or see anything else we should know about, please participate in the creation of our own community avalanche advisory by submitting snow and avalanche observations. You can also call us at 801-524-5304 or email by clicking HERE. In the Logan Area you can contact Toby Weed directly at 435-757-7578.

This advisory is produced by the U.S.D.A. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist.