Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Monday - December 12, 2016 - 6:44am
bottom line

Dangerous avalanche conditions remain in the backcountry, and triggered avalanches are likely on steep upper and mid-elevation slopes. Careful snowpack evaluation, cautious routefinding, and conservative decision-making will be essential for safe backcountry travel today.

  • Heavy snow overloaded preexisting weak faceted snow, and you could trigger persistent slab avalanches on slopes steeper than about 30 degrees.
  • Destructive deep slab avalanches failing near the ground are possible in north facing upper elevation terrain.
  • Wind slab avalanches are likely on steep drifted slopes.



special announcement

***Discount lift tickets for Beaver Mountain, Snowbasin, Powder Mountain, and the Central Wasatch resorts are now available, donated by the resorts to benefit the Utah Avalanche Center. Details and order information here. These make a great holiday gift and all proceeds go towards paying for avalanche forecasting and education!
current conditions

Natural avalanche activity occurred at upper and mid elevations over the weekend. Much colder temperatures are helping to lock things up, and the snow in the backcountry is gradually stabalizing as it adjusts to the load. Dangerous persistent slab avalanche conditions still exist, mainly at upper elevations, and triggered avalanches remain likely.

The Tony Grove Snotel picked up a couple feet of heavy snow with the storm, containing 4.7 inches of water accumulation since Thursday, and the station now reports 95% of average water content for the date. I'm reading 17 degrees this morning at the 8400' site. The UDOT Hwy 89 Logan Summit Wx station reports 20 degrees and northwest winds averaging around 20 mph, and gusting overnight in the upper 40s....

  • Remember, the Tony Grove Road is a busy shared use area, so you have to watch your speed around pedestrians and dogs. The road is not maintained for driving in the winter, so be prepared with shovel and winter survival gear if you attempt the drive.
  • Beaver Mountain welcomes up-hill hiking traffic this time of year as it helps to pack out the slopes, but you should consider it as "backcountry terrain" before they open the lifts to the public on Thursday.
recent activity
  • Observers Saturday reported a large natural avalanche, failing on weak snow near the ground on Chicken Hill in the Bunch Grass drainage.
  • No triggered avalanches were reported from yesterday, and clouds over the high country in the Bear River Range obscured views of most suspect avalanche terrain, but I could see evidence of recent significant natural activity in the Wellsville Range.
  • Yesterday, avalanche reduction teams in the mountains east of Ogden produced numerous avalanches breaking into old snow and several failing on basal facets near the ground.


A sizable natural avalanche on Chicken Hill (12-10-2016)
Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Triggered persistent slab avalanches remain likely at upper and mid elevations in the backcountry. The prolonged storm overloaded preexisting faceted snow, weakened rapidly last week by a large temperature gradient due to the very cold temperatures in the mountains. A persistent mid-pack weakness made up of small grained near surface facets is apparent in test pits..

***Dangerous and destructive deep slab avalanches, failing on weak faceted snow or depth hoar near the ground are possible on upper elevation north facing slopes.

Here' a video look at the pre-storm snow, 12-8-16, Corner Pocket
Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Dangerous wind slab avalanche conditions exist on drifted upper elevation slopes in the backcountry. Northwest winds continued overnight and significant drifting occurred in exposed terrain. Breezy conditions and west winds should continue in the mountains today and gradually decrease overnight. Avoid stiffer recently drifted snow on steep slopes. Drifts may appear rounded and chalky and they may produce hollow, drum-like sounds. Watch for deposits of drifted snow in and around terrain features like gullies, scoops, sub-ridges, and cliff-bands.
weather

Westerly flow will remain over the area through mid week. A weak disturbance will clip northern Utah today. A warm front will lift north through the area late Tuesday through late Wednesday. A strong cold trough will move into the region Friday through Saturday.

Weather Forecast: Tony Grove Lake (41.897,-111.6535), Elevation: 8800'
Today: A 30 percent chance of snow showers, mainly after 11am. Mostly cloudy, with a high near 22. Wind chill values as low as -1. Breezy, with a west wind 21 to 28 mph, with gusts as high as 39 mph. Total daytime snow accumulation of around an inch possible.
Tonight: A 20 percent chance of snow showers before 11pm. Mostly cloudy, with a low around 11. Wind chill values as low as -5. Breezy, with a west wind 20 to 25 mph decreasing to 14 to 19 mph after midnight. Winds could gust as high as 37 mph.
Tuesday: Mostly cloudy, with a high near 22. Wind chill values as low as -4. West wind 13 to 18 mph.
Tuesday Night: A 30 percent chance of snow after 11pm. Mostly cloudy, with a low around 16. West wind 13 to 15 mph. New snow accumulation of less than a half inch possible.
Wednesday: Snow likely, mainly after 11am. Cloudy, with a high near 28. West southwest wind around 15 mph. Chance of precipitation is 70%. New snow accumulation of 2 to 4 inches possible.

general announcements

The early season is a great time to refresh yourself and practice companion rescue techniques with your partners. Companion Rescue Practice Video

Check out Avalanche Canada's "Rescue at Cherry Bowl" story HERE

Between now and Jan 15th: Donate to the Utah Avalanche Center by shopping at Whole Foods Market Utah! When you visit any Utah Whole Foods Market locations, bring your re-usable bags, Whole Foods will donate a dime per bag to the Utah Avalanche Center - if you say DONATE my bag credit.

Remember your information can save lives. If you see anything we should know about, please help us out by submitting snow and avalanche observations. You can also call us at 801-524-5304, email by clicking HERE, or include @utavy in your Instagram. In the Logan Area you can get ahold of your local avalanche forcaster, me (Toby Weed), at 435-757-7578

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 exist.