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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed for
Friday, December 2, 2022
The avalanche danger is HIGH in the backcountry and conditions are very dangerous. Long running natural and human triggered avalanches are likely, and people should avoid all travel in backcountry avalanche terrain. Stay off and out from under slopes steeper than about 30°.
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Avalanche Warning
Widespread avalanche activity is expected and the avalanche danger will be HIGH. In effect from 3 p.m. MST this afternoon until 6 a.m. MST Saturday. For the mountains of Northern Utah and Southeast Idaho including the Wasatch Range, Bear River Range, and Western Uinta Range. A rapid load of heavy snow combined with very strong winds and preexisting weaknesses in the snowpack will create very dangerous avalanche conditions. Both human triggered and natural avalanches are likely. Stay off of and out from under slopes steeper than 30 degrees.
Special Announcements
Our annual party and fundraiser is coming up on December 6 in Logan at the Cache. 19th Annual Utah Avalanche Center Pray for Snow Party and Fundraiser information and tickets HERE.
Join the Utah Avalanche Center and the Division of Outdoor Recreation to celebrate the Fourth Annual Avalanche Awareness week, from December 4 - December 11. Click HERE to view the full list of events for the week.
Weather and Snow
The avalanche danger is HIGH in the backcountry. Heavy snow and drifting overnight overloaded widespread slopes with buried persistent weak layers and poor snow structure. Large natural and human triggered avalanches are likely in many areas, and people should avoid travel in all backcountry avalanche terrain, meaning avoid being on or under slopes steeper than about 30°.
Remote mountain weather stations report around 9 inches of new snow and just under 1" SWE as of early this morning, with perhaps twice that amount in my driveway in West Logan. Yesterday's strong southwest winds on Logan Peak veered early this morning and diminished a little, now blowing from the northwest around 30 mph with 50 mph gusts. It's 5° F at the CSI weather station on Logan Peak at 9700' in elevation and 13° F at the Franklin Basin Snotel site at 8100'.
Snow showers and widespread blowing snow should taper off this morning, and temperatures will drop into the single digits. 15 to 30 mph west winds are expected and wind chill values at around 8500' will be as low as -14° F. It'll be partly sunny tomorrow and the next storm is expected to start impacting the zone on Sarturday night, lasting through Monday.
Recent Avalanches
A party of riders report triggering a few small, manageable, soft slab avalanches on north facing slopes at upper elevations in Providence Canyon on Tuesday.
See our updated list of observed avalanches from across Utah HERE
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Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
People are likely to trigger dangerous slab avalanches of stiffer wind drifted snow failing on a sugary buried persistent weak layer if they venture onto exposed upper elevation slopes. Drifts and wind slabs may be hidden under today's fresh powder. Natural avalanches are likely as more fresh snow is drifted onto steep overloaded slopes.
  • Wind slabs often form on the lee side of exposed ridges and in and around terrain features. Watch for and avoid drifts on gully walls, under cliff bands, along sub-ridges, in scoops, saddles, and sinks.
  • Drifted snow is stiffer and more compacted than non-drifted snow. Last night's strong winds created harder drifts (called hard slabs if they avalanche). Hard slabs are often stubborn, notorious for allowing people to get out on them before releasing, kind of like a mouse trap!
  • Slab avalanches of wind drifted snow failing on a persistent weak layer might be triggered remotely, from a distance, or even below!
  • Today you should avoid travel on or under steep slopes with deposits of wind drifted snow.
  • Freshly formed wind slabs can be quite sensitive and are often remotely triggered.
  • Shooting cracks in drifted snow are a sure sign of instability.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Soft slab avalanches failing on a persistent weak layer of surface hoar, buried by Monday's storm, are likely for people to trigger, even on sheltered and mid and lower elevation slopes steeper than 30 degrees. We've found buried weak sugary snow at all elevations and on slopes facing every direction. So, the PWL (persistent weak layer) problem will get much worse as widespread slopes with poor snow structure are overloaded, and the problem is likely to be an issue for a while. Areas plagued by a very sensitive PWL consiting of buried feathers of surface hoar are widespread, mostly in sheltered and mid elevation terrain. Persitent weak layers consiting of surface hoar are notoriously tricky and avalanches may occur on lower angled slopes than you might expect.
Red Flags indicating the PWL instability will include audible collapses or wumpfs and shooting cracks. Slab avalanches failing on a buried persistent weak layer are likely to be remotely triggered from a distance, hopefully from above or from an adjacent slope, and not from below.
Monday's snow fell on bare ground or very shallow snow on low and many mid elevation sunny slopes, (W, SW, S, SE) so the danger of avalanches is lower, but potential might be higher for hitting rocks.
Additional Information
  • Take the all-new online avalanche courses the UAC built for Know Before You Go or take other online courses listed on the KBYG website (Develop skills -> Online Learning).
  • Get your avalanche rescue gear ready for winter. Put fresh batteries in your transceiver and update the firmware. Inspect your shovel and probe. Get your airbag backpack ready by possibly doing a test deployment and update the firmware if it is an electric version.
General Announcements
Please submit your observations from the backcountry HERE.
For a list of avalanche classes from the Utah Avalanche Center go HERE
For information on where you can ride your sled or snowbike, check out this map of the winter travel plan for the Tony Grove and Franklin Basin Areas HERE.
The Tony Grove Road and other forest roads in the Logan Ranger District are not maintained for wheeled vehicles in the winter.
This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.
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