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Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed on
Tuesday morning, December 29, 2020
There are areas with CONSIDERABLE danger on steep drifted slopes at upper and mid elevations. Strong and sustained east winds yesterday stripped the powder off of upper elevation slopes facing the east half of the compass and built drifts and wind slabs in unusual and perhaps unexpected places. People could trigger dangerous avalanches consisting of drifted snow failing on a sugary persistent weak layer. Slab avalanches, 1 to 3 feet deep, are likely in some areas, and could be triggered remotely or from a distance.
  • Shallow snow coverage dictates careful travel, and hitting rocks and other obstacles still presents a serious risk in the backcountry.
  • Cracking and collapsing indicate unstable snow.
  • Continue to avoid and stay out from under drifted slopes steeper than about 30 degrees.
Low
Moderate
Considerable
High
Extreme
Learn how to read the forecast here
Special 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.
Weather and Snow
Several inches of new snow accumulated over the weekend in the mountains, but strong and sustained east winds yesterday stripped the powder off of upper elevation slopes facing the east half of the compass and built drifts and wind slabs in unusual and perhaps unexpected places. Lower angled slopes in sheltered terrain offer the best conditions, because on steeper slopes you will still sink into the underlying less consistent older snow. Overall snow coverage is still very shallow in the Logan Zone, and the snow that was on the ground in November and early December is very loose and sugary. In many places you still sink all the way to the ground when you hop off your sled.
Observers continue to report triggering booming audible collapses in many areas. These whumpfing sounds are a red flag indicating unstable snow, telling us that dangerous avalanche conditions exist.
Yesterday's sustained and strong east winds created all sorts of havic at upper elevations, and today we should be on the lookout for drifts in unusual or unexpected places. It will be mostly sunny, breezy, and cold in the mountains again today. High temperatures will remain below twenty at 8500', and with a north wind, wind chill values will be as as low as -12° F. A weakening storm is likely to bring a bit more snow to the Logan Zone for the last day of 2020, a bit more potential exists for accumulating snow this weekend, and the upper level weather pattern in the extended forecast looks to become more progressive in the first week of 2021.
Recent Avalanches
Observers report seeing some recent natural activity yesterday above Tony Grove Lake and in the Mount Naomi Wilderness.
On Sunday, we remote triggered a 4' deep, 40' wide, fairly hard drift from about 100' away in Long Hollow, north of Beaver Mt. The drift had no where to run in the low angled terrain and stopped within about 50', leaving a jumble of big blocks across slope.
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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!
The faceted crystals at the bottom of the snow pack are getting bigger and are becoming more well developed. This is becoming depth hoar, and it will haunt us in the future!
Avalanche Problem #2
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Drifting of Sunday's fresh snow from strong east winds yesterday and overnight built stiffer drifts and wind slabs in unusual or perhaps unexpected places, and human triggered avalanches of wind drifted snow are possible on slopes at all elevations facing any direction. These will most likely be found near ridge tops and in and around terrain features like gullies, cliff bands, and sub ridges. Stiffer drifts or harder wind slabs are usually not as sensitive as soft new ones, and they may allow people to get out on them and into avalanche paths before releasing. People are likely to trigger soft or harder slab avalanches of wind drifted snow, 1 to 3 feet deep, on steep upper and mid elevation slopes, especially where drifts formed on weak, sugary, or faceted snow.
  • Even a small avalanche could be very dangerous due to shallow early season snow conditions.
This small remote triggered avalanche of wind drifted snow in Long Hollow failed on a sugary persistent weak layer.
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.
Paige shows what we are talking about when we mention faceted snow in our forecasts. 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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