Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - December 24, 2016 - 6:55am
bottom line

Dangerous avalanche conditions will develop in the backcountry today as a powerful Christmas storm impacts the Logan Zone. Expect rapidly rising avalanche danger, with significant new snow expected, strong south winds, and widespread weak surface snow.

  • Careful snowpack evaluation, cautious route-finding and conservative decision making are essential for safe travel.



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 25 degrees this morning and there's one inch of new snow. There's 44" of total snow at the site, containing 110% of average water content for the date. It's 20 degrees at the CSI Logan Peak weather station at 9700', and I'm reading intensifying east-southeast winds currently averaging around 30 mph, with gusts pushing 60 mph. It'll be a stormy winter day in the mountains and a day with increasing avalanche danger.

Feathery surface hoar or frost crystals on the snow surface yesterday in the Franklin Basin Area are now buried under a bit of new snow from overnight... These glittery crystals may be the failing layer for this weekend's storm snow avalanches on some slopes, or they could become a tricky buried persistent weak layer for triggered avalanches next week. (12-23-16)
recent activity

A natural avalanche cycle occurred across the zone last Friday during the storm and included sizable activity on south and east facing slopes. No avalanches were reported locally since then.
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

The danger of wind slab avalanches is on the rise with a few inches of nice new snow and strong east winds overnight and early this morning. Heightened wind slab conditions already exist in exposed upper elevation terrain and the danger will rise throughout the day with continued drifting.

  • Wind slabs may appear rounded and chalky and they may produce hollow, drum-like sounds.
  • Watch for and avoid stiffer deposits of drifted snow on the lee side of major ridges and in and around terrain features like gullies, scoops, sub-ridges, and cliff-bands.
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

The danger of storm slab avalanches will rise during the day and overnight as new snow stacks up on weak surface snow.

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
  • Mid-pack weak layers of buried graupel and small-grained near surface facets exist, and you might trigger an avalanche stepping into old snow in some areas.
  • Dangerous deep slab avalanches, failing on weak faceted snow or depth hoar near the ground are possible, especially on upper elevation north facing slopes. It would be difficult for a person to trigger a deep slab right now, but any such avalanche could be quite large and deadly. Large avalanches might be triggered from areas where the slab is thin, like wind-swept, shallow, or rocky areas. This problem appears limited to slopes that had some snow-cover before Thanksgiving.
  • Additional overloading and drifting snow from the storm will cause a rising danger of persistent and deep slab avalanches on some slopes.
weather

The National Weather Service has continued a Winter Storm Warning for most of Utah and southern Idaho. A significant winter storm will affect the region over the Christmas Weekend, causing poor traveling conditions across the region and bringing copious snow and strong winds to the mountains through Sunday night.

A moist and cold winter storm will slowly cross the Great Basin during the weekend.

Weather Forecast: Tony Grove Lake (41.897,-111.6535), Elevation: 8800'
Today: Snow. High near 25. Breezy, with a south wind 18 to 26 mph, with gusts as high as 38 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 5 to 9 inches possible.
Tonight: Snow. Low around 13. Wind chill values as low as -2. South southeast wind 9 to 15 mph becoming northwest in the evening. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible.
Christmas Day: Snow. High near 17. Wind chill values as low as -8. Windy, with a west wind 22 to 30 mph, with gusts as high as 43 mph. Chance of precipitation is 100%. New snow accumulation of 9 to 13 inches possible.
Sunday Night: Snow showers likely, mainly before 11pm. Cloudy, with a low around 7. Wind chill values as low as -10. Blustery, with a west northwest wind around 22 mph, with gusts as high as 32 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 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.

We will update this advisory regularly on Monday, Wednesday, Friday, and Saturday mornings by about 7:30...

Remember your information can save lives. If you see anything we should know 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 me 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.