Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - December 17, 2016 - 7:06am
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Dangerous and complex avalanche conditions exist in the Logan Area backcountry, with large and potentially deadly human-triggered avalanches likely on upper elevation slopes steeper than about 30 degrees.

  • Today there are many avalanche problems to beware of including storm snow, cornice fall, and wind slab avalanches, as well as persistent slabs breaking into old snow and deep slabs failing near the ground.
  • You should stay off of and out from under steep slopes and avoid avalanche runout zones.
  • Careful snowpack evaluation, cautious route-finding and conservative decision making will be essential for safe travel in the backcountry this weekend.



special avalanche bulletin

There’s a HIGH avalanche danger in the Western Uintas, and we’ve continued the Avalanche Warning. Dangerous avalanche conditions still exist in the backcountry across the mountains of Central and Northern Utah, with large and potentially deadly human triggered avalanches likely on upper elevation slopes steeper than about 30 degrees. Backcountry travelers should and stay off and out from under steep slopes and avoid avalanche runout zones. Careful snowpack evaluation, cautious route-finding and conservative decision making will be essential for safe travel in the backcountry this weekend.
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

The Tony Grove Snotel at 8400' reports 4 degrees with 1.5" of snow water equivelent in the last 24 hrs and 2.7" from the storm. The site now reports 113% of average water content for the date. The Franklin Basin ID Snotel to the north and the Doc Daniel Snotel to the south report about 18" of heavy new snow from the storm. The CSI Logan Peak weather station at 9700' reports 4 degrees below zero, and the wind sensor is rimed. Winds diminished significantly overnight on Mt Ogden and at the UDOT Hwy 89 summit station where there's now only a light breeze out of the northwest.

Beaver Mountain opened Thursday with great snow cover, and offers a safe powder option on a day with dangerous avalanche conditions in the backcountry. Remember though, that you are entering the backcountry when you leave the ski area boundaries...
recent activity

We noticed a few good sized fresh natural wind slab avalanches and widespread shallow soft slabs Thursday in upper Providence Canyon...

A fresh wind slab avalanche on Providence Peak and a coyote triggered shallow soft slab on both sides of a small gully in the forest. 12-15-16

We've received a couple reports last week of audible collapsing in the local backcountry, with an extremely large and loud whumpf reported from the top of Garden City Bowls on Monday morning. Whumpfs are audible collapses of the snowpack, indicating areas of unstable snow.

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
  • Storm snow avalanches, or soft slabs involving the new snow, are likely on slopes where the heavy new snow accumulated on shallowly buried weak surface snow.

  • Dangerous wind slab avalanche conditions exist on drifted slopes at upper and mid elevations. Strong south winds in the past couple days and northwest winds yesterday evening and overnight created wind slabs in exposed terrain. The drifting also built out ridgetop cornices that are again likely to be sensitive to human weight today. Watch for and avoid deposits of drifted snow in and around terrain features like gullies, scoops, sub-ridges, and cliff-bands. Drifts and wind slabs may appear rounded and chalky and they can produce hollow, drum-like sounds. Wind slabs that formed during the pre-storm south wind on Wednesday night and Thursday will be buried and hidden by yesterday's snow.

On some slopes, feathery frost crystals on the snow surface called surface hoar were likely buried and preserved by a few inches of snow Wednesday. This will likely be the weak layer for some of today's storm and wind slab avalanches. (Davis, 12-12-16)
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 and destructive deep slab avalanches, failing on weak faceted snow or depth hoar near the ground are likely today, especially on upper elevation north facing slopes. Drifting snow in the past few days, and the load from last yesterday's heavy snow, created dangerous deep slab conditions on slopes with preexisting poor snow structure.


Avalanche Problem 3
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 are likely on some steep slopes at upper and mid elevations. A strengthening persistent mid-pack weakness made up of small grained near surface facets is still apparent in test pits, and avalanche reduction teams in the Ogden Area Mountains produced a few avalanches failing in old snow yesterday.
weather

A Pacific storm system will continue to exit the area today. A cold airmass will be left in its wake and will remain entrenched across the region into early next week.

Weather Forecast: Tony Grove Lake (41.897,-111.6535), Elevation: 8800'
Today: Mostly sunny and cold, with a high near 4. Wind chill values as low as -26. North northwest wind 9 to 14 mph.
Tonight: Mostly cloudy, with a steady temperature around -5. Wind chill values as low as -22. West northwest wind around 10 mph.
Sunday: Mostly sunny and cold, with a high near 8. Wind chill values as low as -26. West wind around 9 mph.
Sunday Night: Partly cloudy, with a low around -2. Wind chill values as low as -17. West wind 8 to 10 mph.
Monday: Mostly sunny, with a high near 20. West wind 13 to 18 mph.

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.