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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Sunday morning, December 20, 2020
Dangerous avalanche conditions and CONSIDERABLE danger exist in the backcountry on drifted mid and upper elevation slopes. People are likely to trigger dangerous avalanches of stiff wind drifted snow, failing on a sugary persistent weak layer. Drifting from southwest winds today will cause increasing danger in exposed terrain, and some natural avalanches are possible.
  • Avalanches could be triggered remotely or from a distance.
  • Stay off and out from under drifted slopes steeper than about 30 degrees.
Low
Moderate
Considerable
High
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Special Avalanche Bulletin
AVALANCHE CONDITIONS REMAIN DANGEROUS FOR THE MOUNTAINS OF NORTHERN UTAH, INCLUDING THE WASATCH RANGE, THE WESTERN UINTAS, AND THE BEAR RIVER RANGE. RECENT HEAVY SNOWFALL AND DRIFTING FROM STRONG WINDS HAS CREATED AREAS OF UNSTABLE SNOW. HUMAN TRIGGERED AVALANCHES ARE LIKELY. TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED. STAY OFF OF AND OUT FROM UNDERNEATH SLOPES STEEPER THAN 30 DEGREES
Special Announcements
Beaver Mountain is closed to uphill travel so the crew can set up for opening day on Tuesday.
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.
Weather and Snow
Heavy snow accumulated and was drifted onto steep mountain slopes with Thursday's storm, overloading widespread sugary preexisting weak snow from November. Many natural and remote triggered avalanches where observed Friday in the Logan Zone.
Before the storm most slopes had little more than about 2' of total snow, and a steep temperature gradient turned the shallow snow into loose sugary or faceted grains. In many places, the weak snow is easy to punch through to the rocks below. There were many natural and human triggered avalanches in the Bear River Range, observed on Friday. The 1' deep soft slab avalanches were fairly forgiving and nobody got caught, but drifting yesterday and today deposited stiffer drifts into lee slope avalanche starting zones and around terain features like gullies, cliff bands, and sub ridges
Numerous natural and remote triggered avalanches where observed in the Bear River Range Friday. This one is on White Pine Knob. (ward)
Expect mostly cloudy conditions in the mountains today, with a chance of some snow showers and fairly strong west wind blowing along the ridges. Clouds will remain over the zone and it will be pretty cold, with temperatures rising to near 30°F and a chance for some more snow showers during the day. Blustery conditions will continue tonight, and snow showers could produce an inch or two of accumulation . A storm, mostly passing to our north will bring a few inches of snow to upper elevation slopes in the Bear River Range Tuesday and Tuesday night.
Recent Avalanches
Numerous natural avalanches occurred Thursday night in the Tony Grove Area, and several "user friendly" avalanches were remote triggered by different parties in the area Friday. Most of the avalanches were remote triggered from a distance before folks committed to steep slopes, and nobody got caught. The avalanches on north and east facing slopes from about 7500' up to 9000', were mostly about 1' deep, with some about 2' deep, and 20' to 400' wide. All failed on faceted snow and running on the mid-November thermal crust, leaving 1 to 2' of very sugary snow in bed surfaces...
Remote triggered avalanche from Friday above Tony Grove Lake...
Avalanche Problem #1
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Many slopes in the region are plagued by layers of weak faceted snow formed during the prolonged November dry spell.
Avalanches failing on a persistent weak layer can be very sensitive, and they might be triggered remotely, from a distance, or worse from below!
A thick layer of very weak, sugary, or faceted snow will likely be a problematic persistent weak layer on many slopes, as future snow overloads it.
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
It will be rather windy again today at upper elevations, and there is plenty of powder for it to drift around. Southwest and westerly winds formed stiffer drifts in lee slope avalanche starting zones and around terain features like gullies, cliff bands, and sub ridges. Drifting will continue and some natural avalanches are possible today. Harder drifts or slabs are usually not as sensitive, and they may allow people to get out on them and into avalanche paths before releasing. People are likely to trigger dangerous avalanches of wind drifted snow, 1 to 2 feet deep on steep upper and mid elevation slopes where drifts formed and are building up again today on weak, sugary, or faceted snow.
  • Even a small avalanche could be very dangerous due to shallow early season snow conditions.
Additional Information
Everybody should make time to examine and practice with your avalanche rescue equipment, and convince your backcountry partners to practice with you. Watch our companion rescue video HERE
My tip for avoiding avalanches in the backcountry is to keep your slope angles low. Avoid and stay out from under slopes steeper than about 30 degrees. Get a tool to measure slope angle and practice with it in the backcountry. Watch the video HERE.
General Announcements
Visit this website with information about Responsible Winter Recreation by the Utah Office of Outdoor Recreation.
We've kicked off Season 4 of the UAC podcast with a Conversation with American Avalanche Institute owner Sarah Carpenter. You can stream it HERE or wherever you get your favorite podcasts.
The Tony Grove Road is not maintained for wheeled vehicles in the winter.
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.
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