Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Friday - February 2, 2018 - 7:16am
bottom line

Heightened avalanche conditions exist in the backcountry. Cornice fall and wind slab avalanches are possible in drifted upper elevation terrain. Dangerous human-triggered persistent slab avalanches are gradually becoming less likely, but remain possible on steep slopes with poor snow structure.

  • Evaluate snow and terrain carefully.
  • Avoid travel on or under large ridge top cornices and steep drifted slopes.



special announcement

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current conditions

The Tony Grove Snotel at 8400' reports 31°F, and there's 56 inches of total snow at the site containing 87% of normal SWE (or Snow Water Equivalent). It's 30°F at UDOT Hwy 89 Logan Summit and a northwest wind is blowing 5 to 10 mph this morning. Heightened avalanche conditions exist on drifted upper elevation slopes where human triggered cornice falls and wind slab avalanches are possible. Dangerous persistent slab avalanches continue to become less likely but remain possible slopes plagued by poor snow structure. It rained Saturday night and there's a thick and brittle translucent ice-crust on the snow surface at upper and mid elevations in the Bear River Range.

recent activity

Yesterday, we could see evidence of some recent sizable cornice falls and resulting wind slab avalanches off the south ridge of Mt. Magog.

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

An incessant and strong westerly wind continues to drift snow at upper elevations, in some cases stripping Saturday night's rime-crust off windward slopes and open fetch areas, forming stiff wind slabs in lee slope deposition areas, and building huge cornices along north-south oriented ridge lines. The widespread rime or rain-crust is holding snow in place and preventing drifting in most places, especially at mid and lower elevations. Human triggered cornice fall and wind slab avalanches are possible, and some large natural cornice falls are possible as strong westerly winds continue into the weekend.

  • Watch for and avoid drifted snow on steep lee slopes and in and around terrain features like sub-ridges, gullies, scoops, and rock outcrops.
  • Avoid travel on or under large ridge top cornices, which might break further back than expected and could trigger wind slab avalanches on drifted slopes below.
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

Widespread buried faceted layers appear dormant now, and dangerous persistent slab avalanches are becoming less and less likely to trigger with time. Even so, avalanches stepping into old snow remain possible on steep slopes, especially those with shallow snow and poor snow structure. We continue to see full propagation and clean, quality 1 shears in some of our test pits, and one party reported triggering a large audible collapse yesterday on a low elevation northeast facing slope in the North Sinks Area.

  • Some drifts likely formed in areas with poor snow structure, overloading weak faceted snow, and dangerous persistent slab avalanches involving previously drifted snow are possible.
  • Pay attention to possible signs of instability like cracking and whumpfing or collapsing, but remember these signs aren't always present when avalanches are triggered, so you have to dig down into the snow to find poor snow structure.
  • Persistent slab avalanches are often triggered from low on the slope, and might be triggered remotely, from a distance or below.‚Äč
weather

High pressure aloft along the west coast will maintain a somewhat moist northwest flow across the Great Basin the next several days. A series of weak weather disturbances embedded in this northwest flow will cross northern Utah and southwest Wyoming through the weekend, with a stronger system early next week.

  • Today: A 40 percent chance of snow. Cloudy, with a high near 36. Breezy, with a west wind 20 to 22 mph. Total daytime snow accumulation of less than one inch possible.
  • Tonight: Snow likely. Cloudy, with a steady temperature around 35. Windy, with a west wind 21 to 30 mph, with gusts as high as 44 mph. Chance of precipitation is 70%. New snow accumulation of 2 to 4 inches possible.
  • Saturday: A 50 percent chance of snow. Cloudy, with a high near 35. Breezy, with a west wind around 25 mph, with gusts as high as 39 mph. New snow accumulation of 1 to 2 inches possible.
general announcements

We have discount lift tickets for Alta, Snowbird, Brighton, Solitude, Snowbasin,and Beaver Mountain. Details and order information here. All proceeds from these go towards paying for avalanche forecasting and education!

The UAC Marketplace is online. The holiday auction is closed, but our online marketplace still has deals on skis, packs, airbag packs, beacons, snowshoes, soft goods and much more.

Benefit the Utah Avalanche Center when you buy or sell on eBay - set the Utah Avalanche Center as a favorite non-profit in your eBay account here and click on eBay gives when you buy or sell. You can choose to have your seller fees donated to the UAC, which doesn't cost you a penny

Episode 3 of the UAC podcast is live. We talk with UDOT Avalanche Program Supervisor Bill Nalli on how he and his teams keep the Greatest Snow on Earth from avalanching over the open roads and highways of the state. Check it out on ITunes, Stitcher, the UAC blog, or wherever you get your podcasts.

Now is a great time to practice companion rescue techniques with your backcountry partners. Here's our rescue practice video.

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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 tweet or Instagram.

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.