Forecast for the Logan Area Mountains
Issued by Toby Weed on
Monday morning, December 14, 2020
Monday morning, December 14, 2020
Heightened avalanche conditions exist on upper and mid elevation slopes where people could trigger slab avalanches consisting of fresh drifted snow, failing on a sugary persistent weak layer. Areas with CONSIDERABLE danger may exist or develop today on drifted upper elevation slopes facing northwest through southeast, and avalanches could be triggered remotely or from a distance.
- Evaluate snow and terrain carefully, and stay off and out from under steep drifted slopes.
Low
Moderate
Considerable
High
Extreme
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Special Announcements
The holiday season is right around the corner!! Looking for that special something for your partner?
Well, we've got an easy shopping solution for you ...Buy your gifts at our Pray for Snow online auction and support the UAC in Logan. HERE
Well, we've got an easy shopping solution for you ...Buy your gifts at our Pray for Snow online auction and support the UAC in Logan. HERE
Weather and Snow
About 4 inches of new snow fell last night at upper elevations in the Bear River Range, drifted by fairly strong south and southwest winds. Snow showers will continue today, diminishing by evening, with 1 to 3 more inches of accumulation possible. Expect cold unsettled weather to continue through the week, with heavy snow possible in the mountains Thursday and Thursday night.
Currently, hitting rocks or other shallowly buried obstacles presents a significant hazard in the backcountry. A few inches of nice light powder now obscures many hazards. Most slopes have less than about 2' of total snow, and a steep temperature gradient is turning the shallow snow into loose sugary or faceted grains. In many places, the weak snow is easy to punch through to the rocks below.
Recent Avalanches
An observer reports easily triggering fresh wind slabs and sluffs of new snow at upper elevations in the Central Bear River Range Saturday. One drift, intentionally triggered, produced a small soft slab avalanche, about 30' wide, running a couple hundred feet. The party found fresh drifts up to about 2 feet deep in exposed terrain.
Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Avalanches of wind drifted snow are possible on may upper and mid elevation slopes where overnight winds deposited drifts of last weekend's fresh snow. Today's new snow will obscure the older drifts, while west and then northwest winds today will build new ones. People are likely to trigger wind slab avalanches on some steep upper elevation slopes where drifts formed on weak, sugary or faceted snow. In more sheltered terrain, loose sluffs and shallow soft slabs of new snow are possible because the older snow underneath is very weak, faceted, and loose.
- Even a small avalanche could be very dangerous due to shallow early season snow conditions. You do not want to get caught and carried over rocks or strained through bushes and stumps, so it's best to avoid travel on all steep drifted slopes.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
During the extended November dry spell, the shallow snow on the ground was subjected to a significant temperature gradient and resulting sublimation caused the snow on many slopes to become sugary, non-cohesive, faceted, and very weak. Drifted snow is a wind slab and when these stiffer, more cohesive slabs develop on top of weak, sugary, faceted snow they are unstable. Avalanches failing on a persistent weak layer can be very sensitive, and they might be triggered remotely, from a distance, or worse from below!
In more sheltered area and down in the basins and canyon bottoms, glittering surface hoar feathers on the snow surface were common before the light snow this weekend. These also could become the failing persistent weak layer in future avalanches when buried by enough snow to create a slab.
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.
General Announcements
Visit this website with information about Responsible Winter Recreation by the Utah Office of Outdoor Recreation.
If you missed the 13th Annual Utah Snow and Avalanche Workshop, the recordings are available for purchase from the UAC Store. HERE
The Tony Grove Road is not maintained for wheeled vehicles in the winter.
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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 advisory 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.