Logan Avalanche Advisory

Forecaster: Toby Weed

SPECIAL ANNOUNCEMENT

The National Weather Service has issued a Winter Storm Warning for the mountains across the region through tomorrow afternoon. Heavy snowfall with possible accumulations of up to 1-2 feet, and sustained northwest winds of 20 to 30 mph are possible....


BOTTOM LINE

Danger by aspect and elevation on slopes approaching 35° or steeper.
(click HERE for tomorrow's danger rating)


Danger Rose Tutorial

This morning there is a level 2 or MODERATE avalanche danger in the backcountry, and heightened avalanche conditions exist on drifted upper and mid elevation elevation slopes. Triggered wind slab and isolated deep slab avalanches are possible in steep exposed terrain...Expect an increasing avalanche danger today with a Winter Storm Warning, heavy snowfall, and sustained winds forecast... The danger at upper elevations is likely to rise to Level 3, CONSIDERABLE by afternoon, especially in areas that receive significant accumulations and drifting...Careful snowpack evaluation, cautious route finding and conservative decision making will become essential in the backcountry today....


CURRENT CONDITIONS

The productive storm earlier this week filled in the rocky upper elevation terrain across the region with several feet of dense and drifted snow. Lower elevations also did fairly well, but there's only a foot or less at most trailheads and front side canyons. Winds have damaged the snow surface in exposed areas, but sheltered slopes are still soft and powdery.... All this will change today with several inches of snow possible.

The Tony Grove Snotel reports a bit of new snow and 3/10s of an inch of water overnight and 47 inches of total snow containing 10.7 inches of water. The Campbell Scientific Logan Peak weather station reports sustained 15-20 mph winds out of the south overnight, shifting from the west this morning. It's 12 degrees at 9700'.


RECENT ACTIVITY

Tragically,a snowmobiler from Evanston, Wyoming was killed by a hard slab avalanche in the Western Uinta Mountains on Friday. Our condolences go out to his family and friends. We have a preliminary report and Craig Gordon will post a more complete report today....

Locally, I noticed evidence a fair amount of natural activity at upper elevations from during the productive and windy storm earlier in the week. Some of these were large and substantial hard slab avalanches....see list


THREAT #1

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

Stiff, freshly formed wind slabs 1-2 feet deep or deeper may be sensitive to human triggering today. These most likely built up in exposed upper elevation terrain and in and around terrain features like gullies, sub-ridges, scoops, and cliff bands.... Lee slopes below building cornices are suspect. Always a good idea to avoid steep drifted slopes with trees or other terrain traps below.


THREAT #2

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

Dangerous deep hard slab avalanches are possible on isolated, upper elevation slopes. Hard slab avalanches, several feet deep, may fail on sugary snow under a rime-crust formed on 11-14... Although you are not likely to trigger one on most slopes today, you could on a very steep smooth slope above around 8500' and this type of avalanche could be quite large, destructive and very dangerous...

New additional loading from today's storm could reactivate the weakness and the danger will rise as snow piles up and is drifted into avalanche starting zones today....


THREAT #3

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

New snow may rapidly pile up on suspect surface snow and loose snow and soft slab avalanches will become more likely this afternoon on steep slopes with significant deposits.....


MOUNTAIN WEATHER

The National Weather service has issued a Winter Storm Warning for the mountains through 4:00 tomorrow... We'll see snowfall most of the day today, with 6" or so likely by evening. 1 to 2 feet of powdery accumulation is forecast for favored upper elevations by Monday morning. We're hoping for fairly light density snow, but increasing and sustained northwest winds are forecast for this afternoon... Temperatures will drop to around 5 degrees F tonight... Snow showers should tapper off tomorrow, and it will be cold with near zero daytime temperatures.

More snow is likely next week, but the models disagree as to timing and intensities of the storms.....


GENERAL ANNOUNCEMENTS

Don't miss our annual Pray for Snow party and fundraiser, Wednesday December 1st at the Italian Place.

We're offering another free backcountry avalanche awareness/Know Before You Go talk on Tuesday, December 7 at 6:00 downstairs at the Logan Ranger District office 1500 E Hwy 89 in Logan....

You can view a photo summary of last year's avalanche activity in the Logan Area HERE

Send us your avalanche and snow observations. You can also call me at 435-757-7578, or email to uac@utahavalanchecenter.org

Donate to your favorite non-profit – The Friends of the Utah Avalanche Center. The UAC depends on contributions from users like you to support our work.

This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.


This information does not apply to developed ski areas or highways where avalanche control is normally done.  This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.


This advisory provided by the USDA Forest Service, in partnership with:

The Friends of the Utah Avalanche Center, Utah Division of State Parks and Recreation, Utah Division of Emergency Management, Salt Lake County, Salt Lake Unified Fire Authority and the friends of the La Sal Avalanche Center. See our Sponsors Page for a complete list.