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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed for
Wednesday, December 19, 2012

The danger is MODERATE (level 2) and wind slab avalanches are possible on steep drifted slopes in the majority of terrain in the Logan backcountry today. But, there are also localized areas with a CONSIDERABLE (or level 3) danger, and you might trigger dangerous deep slab avalanches up to 4-feet-deep on some steep drifted upper and mid elevation slopes with buried persistent week layers. Avalanches in some areas might be triggered remotely from a distance or below. Evaluate the snow and terrain carefully , and make conservative decisions regarding your route selection. ..

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Weather and Snow

The Tony Grove Snotel reports 3.2" of water accumulation from the Sunday/Monday storm, and 2 or 3 feet of fresh snow. There's 51 inches of total snow, 101% of average for the date, and it's a chilly 4 degrees at 8400' this morning. Sustained southwest winds and gusts well above 60 mph accompanied the heavy snowfall, dumping ridiculous quantities of snow into upper elevation lee slopes. I found 4 to 5 feet of fresh snow from the past couple days in my snow pits on east facing slopes at around 9000' in the Tony Grove Area. I'm reading -3 degrees this morning at Campbell Scientific's 9700' Logan Peak weather station, and wind from the north-northwest averaging around 10 mph. The new snow was supportable in the upper layers, and I would only sink in around 6 inches into nice powder on the sled and skis, but as soon as I dismounted I would sink to my thighs in the fresh snow. Trail breaking was much easier than I expected and I found very smooth and enjoyable fast powder conditions....

Recent Avalanches

Yesterday, I could see mostly buried evidence of natural avalanche activity in the Tony Grove Area and the Wellsville Range. It looked like the avalanches occurred at some point during the intense storm on Monday, mostly on east facing slopes with starting zones around 9000' in elevation. Resorts in the Ogden Area report triggering some good sized avalanches with explosive testing yesterday, and one sizable avalanche was triggered by a snow board rider in the Central Wasatch Range near Brighton....

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

There are areas with poor snow structure where you might 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 load from the Sunday/Monday storm may have caused these layers to become activated in some areas, and dangerous deep slab avalanches, up to around 4-feet-deep are possible.. I found several feet of fresh snow at upper elevations in the Tony Grove Area yesterday, and in many areas It appears as though it would be difficult for the weight of a person to trigger a slab with the weak layer now buried well over a meter deep. I'm more concerned about areas where the fresh slab is thinner, on windswept rocky slopes or mid elevation shady slopes that were holding a bit of old faceted November snow...Avalanches in some areas might be triggered remotely from a distance, or worse, from below. Pay close attention to red flags like audible collapsing and cracking, and be willing to reevaluate or turn back.

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

Triggered wind slab avalanches are possible on some steep slopes today. I found these to be fairly well welded in place yesterday, with the cold temperatures apparently helping matters. Stiff wind slabs still exist on the lee sides of major ridgelines and in and around terrain features like gullies, scoops, sub-ridges, cliff bands, and rock outcroppings.. 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. Many of these are hidden however, buried and obscured by the last few inches of powder accumulated late Monday or Monday night..

Additional Information

We might see a bit of sun and/or a bit of snow today. Mountain temperatures should climb into the lower teens. North winds around 10 mph will swing around from the west, and there's a 20% chance of snow. A high pressure system will build into the region and control the weather pattern through the rest of the week. Temperatures will drop back down into the lower single digits tonight and it'll be mostly cloudy. There is a better chance for a bit of sunshine tomorrow. Expect rather benign weather into the weekend, 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.

The Friends of the Utah Avalanche Center in Logan have a two person pass for a day of powder skiing or riding with Park City Powder Cats, and they're opening this weekend. If you are interested in a good deal for a memorable powder experience call Paige at 435-757-2794....

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.

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