Issued by Toby Weed on Monday morning, February 22, 2021
Dangerous avalanche conditions are widespread in mid and upper elevation terrain, and CONSIDERABLE danger remains on many steep slopes in the backcountry. People are likely to trigger large avalanches failing on a deeply buried persistent weak layer, and natural avalanches are possible in drifted terrain. The danger is HIGH and there are very dangerous conditions on drifted upper elevation slopes in some parts of the forecast zone. Avalanches could be triggered remotely, or from a distance, and are likely to be very large, destructive, and potentially deadly.
Avalanches are possible at all elevations, but you can find safer conditions in sheltered terrain, at lower elevations, and on gentle lower angled slopes.
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 drifted slopes steeper than about 30 degrees.
We are very sad to report that on 2-20-2021, a 48-year-old Preston man was killed in an avalanche east of Mount Sherman between Grace and Montpelier. Preliminary accident information is available from Local News 8 and Idaho State Journal. We will visit the accident site today...
Weather and Snow
Light snowfall is visible on the Beaver Mountain Webcams this morning. There is a couple inches of new snow with 0.1" SWE in the last 24 hours. It's 22°F at the 8400' Tony Grove Snotel. There is 80 inches of total snow and now 82% of normal SWE. Westerly winds are still drifting snow this morning after blowing snow around at upper elevations yesterday, and winds from the west-northwest are blowing 20 to 30 mph at the UDOT Logan Summit weather station.
Very large natural avalanches were widespread across the Logan Zone early last week. In several areas, natural avalanches were incredibly extensive, with nearly all avalanche paths producing big slides.
We went back up to Wood Camp Thursday to check out a huge natural avalanche that was reported on Wednesday morning.
Snow showers are expected in the mountains this morning, but it will gradually clear. High temperatures at 8500' will be around 25°F, with continuing 15 to 20 mph west winds, and wind chill values around -1°F. Expect increasing clouds and intensifying west-southwest wind tonight. Snow showers are expected tomorrow morning, and it will be windy. Skies will become partly sunny in the afternoon, with high temperatures around 24°F, but dropping into the teens.
The weather pattern appears unsettled through the week, with cool temperature and some snow, but no significant events.
Recent Avalanches
On Saturday 2-20-2021 a party of riders remotely triggered a very large avalanche near Gibson Lakes in Franklin Basin, a few miles north of the Idaho state line. The large group of riders were down in the flats, and well out from under any steep terrain when they heard a very loud "sonic boom" audible collapse, and the whole hill came down... clouds obscured the crown, but the debris field was quite broad.
A couple fresh natural avalanches in the Wellsville Range were observed Saturday from a distance. These were most likely caused by cornice falls, and blowing snow continues to build large sensitive cornices and deep drifts or wind slabs on lee slopes in exposed terrain.
A fresh natural avalanche in the Wellsville Mountain Wilderness, 2-20-2021.
A significant natural cycle occurred across the Logan Zone early last week, with many huge avalanches observed. Very large natural avalanches failing on a buried sugary persistent weak layer and running well out into lower elevation runout zones were widespread and occurred on slopes facing every direction. Reports of extensive natural avalanches include most avalanche paths in the Wellsville Mountain and Mount Naomi Wildernesses, in Upper Spring Hollow, and Wood Camp Hollow. Big avalanches were also reported near Tony Grove Lake, Providence Canyon, Logan Dry Canyon, Cub River, Hillyard Canyon, and in the mountains west of Bear Lake.
Large natural avalanches were widespread across the Logan Zone early last week.
Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Heavy snowfall and westerly winds have added significant weight to slopes that were already near the tipping point. Buried persistent weak layers consisting of sugary faceted snow are widespread across the Logan Zone, and the threat of large and deadly avalanches failing on weak snow near the ground is quite real. Avalanches are likely on steep slopes that did not naturally avalanche recently, where a slab of more cohesive wind drifted snow formed on top of the weak snow.
Avalanches failing on a buried persistent weak layer might be triggered remotely, from a distance, or worse from below!
Cracking and collapsing of the snow are a red flag, indicating unstable snow conditions.
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Avalanches of wind drifted snow are likely where drifts formed recently and are continuing to build today, especially on slopes with buried persistent weak layers.
Wind slabs are often rounded and chalky looking, 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.
Stay well back from cornice edges as they can break much further back than you expect and avalanches are likely on slopes below.
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.
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 clickingHERE, 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.
