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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Sunday morning, February 7, 2021
Heavy snowfall and drifting from strong winds in the past couple days have created dangerous avalanche conditions, and there is CONSIDERABLE danger on many slopes in the backcountry. People could trigger avalanches of wind drifted snow on steep slopes at all elevations. Areas with very dangerous conditions and HIGH danger exist on drifted upper elevation slopes facing northwest through southeast, and large natural avalanches are possible. Buried persistent weak layers consisting of sugary faceted snow are widespread across the Logan Zone, and the serious threat of large and deadly avalanches failing on weak snow near the ground is quite real.
  • Use extreme caution in the backcountry. Expect unstable snow conditions. Choose safe routes in low angled terrain well out from under and not connected to steeper slopes.
  • Avoid and stay well out from under slopes steeper than about 30 degrees.
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Special Announcements
We are very sad to report that four skiers were killed in an avalanche in the backcountry in Mill Creek Canyon above Salt Lake City yesterday. Preliminary Accident Report
Weather and Snow
About 20 inches of snow with 2" of SWE fell during the day Friday. Westerly winds, averaging around 30 mph and gusting into the 50s were blowing during periods of heavy snowfall and drifting has been extreme. West winds continued to drift snow into avalanche starting zones yesterday, and drifting will continue today. With widespread layers of preexisting very weak snow at all elevations and on slopes facing every direction, today's significant increase in load on the fragile snow pack has created very dangerous avalanche conditions in the backcountry.
*Dangerous avalanche conditions exist on steep drifted slopes in the backcountry, and people are likely to trigger dangerous avalanches today.*

It will be partly sunny today with high temperatures at 8500' around 24°F, and continuing strong and gusty west winds. The west winds will moderate a bit tonight but continue through tomorrow. A cooler and more unsettled weather pattern will develop later in the week.
Here is some crazy video from a very close call in the Uinta Mountains yesterday....
Recent Avalanches
Yesterday, backcountry skiers remote triggered a 2' deep and 200' wide avalanche on a fairly low angled slope on Swan Peak above Bear Lake.

With a bit of clearing, a large natural avalanche, likely from during the height of Friday's storm, was obsevered on the east face of Wilderness Peak in the Gibson Lakes Area in Franklin Basin, a few miles north of the Idaho State Line.
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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Heavy snowfall and strong winds added weight to slopes that were already near the tipping point. Very weak sugary or faceted snow is widespread across the region, and natural avalanches are likely where a slab of more cohesive wind drifted snow has formed on top of the weak snow. Large natural avalanches are likely today, especially during periods of rapid accumulation, as heavy snowfall overloads slopes with poor snow structure or unstable snow.
  • Avalanches failing on a buried persistent weak layer might be triggered remotely, from a distance, or worse from below!
  • Stay off of and out from under slopes steeper than about 30 degrees!
  • Cracking and collapsing of the snow are a red flag, indicating unstable snow conditions.
These large faceted snow grains make up a nasty buried persistent weak layer that is widespread in the Logan Zone. It exists on slopes at all elevations across the zone. (Stump Hollow, 1-30-2021)
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Westerly winds yesterday and overnight drifted fresh snow into lee slope avalanche starting zones, and built drifts and wind slabs on steep slopes at upper and mid elevations. Continuing strong west winds today will continue to create thick cohesive slabs and natural avalanches of wind drifted snow are likely, especially where drifts have built on top of a buried persistent weak layer.
  • Wind slabs are often rounded and chalky looking drifts, and they can sound and feel hollow and drum-like when you walk on them.
  • Watch for and avoid stiffer drifted snow near ridge tops and in and around terrain features like gullies, scoops, cliff bands, and sub ridges.
  • Cornices are starting to grow with the recent strong winds. Stay well back from the edge as they can break much further back than you expect.
Additional Information
Do you have the essential avalanche rescue gear (transceiver, probe, and shovel) and do you know how to use them? Watch this video to see how the three pieces of equipment work together. HERE
Please keep practicing with the Beacon Training Park at the Franklin Basin Trailhead. Test yourself and your riding partners. It is free, fun, and easy to use.
General Announcements
Thanks to the generous support of our local resorts, Ski Utah, and Backcountry, discount lift tickets are now available. Support the UAC while you ski at the resorts this season. Tickets are available here.
Visit this website with information about Responsible Winter Recreation by the Utah Office of Outdoor Recreation.
EMAIL ADVISORY. If you would like to get the daily advisory by email you subscribe HERE.
Remember your information can save lives. If you see anything we should know about, please help us out by submitting snow and avalanche observations....HERE. You can also call us at 801-524-5304, email by clicking HERE, or include #utavy in your tweet or Instagram.
I will update this forecast by around 7:30 tomorrow morning.
This forecast is from the USDA Forest Service, which is solely responsible for its content. The forecast describes general avalanche conditions and local variations always occur.