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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Wednesday morning, February 17, 2021
VERY DANGEROUS AVALANCHE CONDITIONS EXIST.
There is HIGH avalanche danger in the backcountry today. Very large and long running natural avalanches are likely to occur. Human triggered avalanches are also very likely, but people should not and most probably will not venture into steep avalanche prone terrain today.
  • AVOID ALL AVALANCHE TERRAIN INCLUDING POTENTIAL AND HISTORIC AVALANCHE PATHS AND RUNOUT ZONES.
Low
Moderate
Considerable
High
Extreme
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Avalanche Warning
VERY DANGEROUS AVALANCHE CONDITIONS EXIST. NATURAL AND HUMAN TRIGGERED AVALANCHES ARE CERTAIN OVER THE NEXT SEVERAL DAYS. STAY OFF OF AND OUT FROM UNDER SLOPES STEEPER THAN 30 DEGREES
Special Announcements
We've completed the report on last Saturday's tragic avalanche in the backcountry in Mill Creek Canyon above Salt Lake City that killed four skiers. Final Accident Report

The UAC in Logan is offering a Youth BC 101 avalanche class for youth aged 16-20 on Feb 21. For more info and to register, click HERE
Weather and Snow
Heavy snow is falling in the Logan Zone again this morning. Around a foot of new snow fell yesterday and several more inches of snow fell overnight, with 2.6" SWE in the last 48 hours at the 8400' Tony Grove Snotel. It's currently 15°F and there is 85 inches of total snow and back up to 82% of normal SWE. Northwest winds are blowing around 15 to 20 mph this morning at the 9700' CSI Logan Peak weather station.
With widespread layers of preexisting very weak faceted snow, the significant increase in load has created very dangerous avalanche conditions on many slopes in the backcountry.

It's snowing at a decent rate again this morning in the Bear River Range and snow is expected to continue today in the mountains, with 2 to 4 inches of accumulation possible by this evening. High temperatures at 8500' will be around 15°F, with moderate northwest winds and wind chill values as low as -3°F. Snowfall will taper off this evening, and we'll see a break in precipitation tomorrow, with continuing cold temperatures, mostly cloudy skies, and moderating westerly winds in the mountains... Another good shot of winter storminess is expected Friday and Saturday, with a foot or more of accumulation possible at upper elevations in the Logan Zone.
Recent Avalanches
Yesterday, we could see evidence of large and long running natural avalanches in the Wellsville Range above Mendon. Some of these appear to have run at least 2500 vertical feet. A stand out in Old Logway Canyon hit Maple Bench, depositing a multi-acre debris pile that is visible from across Cache Valley.

Saturday (2-13-2021), a party of local backcountry skiers remotely triggered a large avalanche in "the Gut" of White Pine Knob above the yurt in the popular Bunch Grass Canyon. The 4' deep and about 500' wide avalanche occurred on a southeast facing slope at around 8900' in elevation. The slope angle at the crown was in the lower 30° range, but the slope rolls to 40 degrees in the Gut itself, and the hard slab was well connected, pulling out even on the lower angled slope above and on each side of the steep section.

Thursday (2-11-2021), riders remotely triggered a large hard slab avalanche on a pretty low angled slope in the Peter Sinks Area (an area that is not well known for avalanches). The avalanche on an east facing slope at around 8300' in elevation was around 100 feet wide and 2 to 7 feet deep, and it stacked large chunks and piles of debris into the trees below. It was the third such hard slab avalanche to occur this week on a fairly low angled slope (between 30 and 35 degrees) and in a rather unexpected place. All have been in the eastern part of the Bear River Range...
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Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Heavy snowfall and continuing westerly winds today will add significant weight to slopes that are 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 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
Westerly winds last week drifted fresh snow into lee slope avalanche starting zones and built drifts and wind slabs on steep slopes at upper and mid elevations. These have since been buried by powder and softer drifts of fresh snow. Expect continued drifting of fresh storm snow from gradually moderating northwest winds today. Natural and human triggered avalanches of wind drifted snow are likely at all elevations.
Avalanche Problem #3
New Snow
Type
Location
Likelihood
Size
Description
Loose dry and soft slab avalanches of new snow are likely in steep terrain today. Rapid loading from heavy new snow or blowing snow could cause avalanches to fail on buried persistent weak layers. Natural avalanches may occur during periods of particularly heavy snowfall or intense drifting. Avalanches may occur in unexpected places and some natural avalanches could run fast and travel far out into lower angled or even flat terrain.
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.