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Forecast for the Ogden Area Mountains

Mark Staples
Issued by Mark Staples for
Thursday, December 1, 2022
It's all about the wind today. Very strong winds from the south blew all day yesterday transporting snow and forming hard slabs of wind drifted snow. These winds have created dangerous avalanche conditions at upper elevations where the danger is CONSIDERABLE.
Mid and low elevations have been affected by strong winds as well and have a MODERATE avalanche danger with heightened avalanche conditions on slopes loaded by the south winds.
HEADS UP - It is time to step back. There is a widespread persistent weak layer buried under Tuesday's new snow. Winds have been relentless. There is another major storm coming tonight, and more snow likely on Sunday/Monday.
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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 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
Join the Utah Avalanche Center and the Utah 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
WIND - Winds from the south continue to rake across the Ogden area mountains. This morning they are steadily blowing 20-30 mph and gusting to 45 mph. Even at low elevations, winds are gusting to 30 mph. These strong south winds will continue today peaking midday.
It's also relatively warm with temperatures at low elevations in the mid 30s F. Temperatures at 9000 ft are in the low 20s F. Today temperatures should warm a few degrees. Clouds will gradually build as the day progresses, and snowfall may start after 5 p.m.
The National Weather Service has issued a Winter Storm Watch from tonight at 9 p.m. until tomorrow at 3 p.m. The heaviest snowfall should happen in the early morning hours tomorrow with snowfall rates greater than 2 inches per hour for several hours. Total precipitation should be 10-18 inches of snow (0.8-1.25 inches of water).
Snow conditions took a dramatic turn for the worse yesterday with a combination of very strong south winds and warm temperatures.
Recent Avalanches
Two days ago, from Ben Lomond to Powder Mountain, there were several reports of natural avalanches and big collapses occurring on a layer of buried surface hoar. This is unusual because surface hoar forms often but typically is destroyed by winds or sunshine before it is buried.
Some hard slab, natural avalanches caused by extensive wind drifting were reported yesterday along the southern end of the Ogden Skyline.
There has been notable avalanche activity further south near SLC where the snowpack is very similar.
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Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Winds were transporting a ton of snow yesterday and will continue doing the same today. They have formed many large, hard slabs of wind drifted snow that can be triggered. With winds increasing midday, I wouldn't be surprised if a few of these wind slabs release naturally.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Dry and cold weather during the middle two weeks of November created a persistent weak layer (PWL) of facets on nearly all slopes. Making matters worse, there is a layer of surface hoar (another PWL) on top of these facets. Both these weak layer layers were buried by Tuesday's storm.
Yesterday on Ben Lomond Peak, Drew and his partner found this layer of buried surface hoar going from low elevations up to 7800 ft. They found the buried facets at all elevations in which they traveled (up to 8800 ft).
Today - More small, soft slab avalanches are possible on this layer. The best place to trigger one will be on slopes with some wind drifted snow.
Tomorrow - Heavy snowfall tonight and tomorrow will make avalanches on this layer larger and they will become very likely. They will either happen on their own as slopes are overloaded by snowfall or will be easily triggered.
Photo from Drew's travels on Ben Lomond Peak. This weak layer failed and produced the shooting crack in the photo. If the slope had been steeper, it would have produced an avalanche.
General Announcements

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.