Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - January 28, 2017 - 7:23am
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Heightened avalanche conditions exist at all elevations, with triggered persistent slab, wind slab, and loose wet avalanches possible. Persistent slab avalanches are possible at mid and lower elevations on slopes with buried surface hoar and in sunny terrain with buried facets above a sun-crust. Evaluate the snow and terrain carefully. Avoid steep drifted terrain, and sunny slopes with saturated surface snow.




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current conditions

Fine deep powder riding conditions exist across the Logan Zone, but rapid accumulation of 2 to 3 feet of snow on weak surface snow Monday and Monday night created dangerous avalanche conditions. With time and settlement the snow will become more stable on most slopes, but areas with unstable snow exist. Two unintentionally triggered avalanches were reported Thursday. The 8400' Tony Grove Snotel reports 22 F and 104" of total snow at the site containing 160% of average SWE (Snow Water Equivalent.) It's 15 F at the CSI Logan Peak weather station at 9700', and the wind is blowing from the northwest at 22 mph.


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Eric and Amy Flygare found deep powder near Tony Grove Lake on Wednesday.

recent activity
  • Thursday (1/26/17); A snowboarder unintentionally triggered a 2.5' deep, 20' wide avalanche on a north facing slope at 8300' just south of Tony Grove Lake. A sledder reported a fresh triggered avalanche on the Providence Quarry slag pile, 1 to 3' deep and about 70' wide.
  • Numerous sizable and long-running natural avalanches occurred during Monday's storm in the Wellsville Range. Several are visible from Hwy 89/91 in the Dry Lake section of Sardine Canyon.
  • Natural storm snow avalanches and very dangerous conditions caused UDOT to close Hwy 89 in Logan Canyon Monday. The canyon was reopened on Tuesday.
  • Numerous triggered avalanches a a couple close calls were reported in the last few days in the Wasatch Back backcountry above Park City. The 2' deep avalanches are failing on the same problematic surface hoar layer

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
  • With Monday's storm a couple feet of snow fell on weak surface snow consisting of surface hoar and/or small-grained sugary facets.
  • Triggered persistent slab avalanches around 2 feet deep, and a few hundred feet wide are possible.
  • Recent triggered avalanches in the Park City area failed on this weak layer, which also exists in the Logan Zone.
  • Buried surface hoar exists mainly in sheltered mid and lower elevation terrain, and we've found it on east, north, and west facing slopes.
  • Avalanches on surface hoar have a nasty reputation for failing on low angled and low elevation slopes.
  • A weak layer of small facets on top of a sun-crust plagues some sunny upper and mid elevation slopes. This (radiation re-crystallization?) layer was the likely culprit in a few recent avalanches in unexpected sunny areas. (See Greg Gagne's observation from Wednesday HERE )


  • Feathery surface hoar crystals like these from last week in the Wellsville Range are formed by frost growing on the snow surface.


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

Heightened wind slab avalanche conditions exist in drifted terrain.

  • Northwest winds created fresh wind slabs in terrain features and lee slope avalanche starting zones.
  • Wind slabs made up of stiffer drifted snow often look rounded and chalky and may produce hollow, drum-like sounds.
  • Avoid drifted snow on the lee side of ridges and in and around terrain features like gullies, scoops, sub-ridges, and cliff-bands.
  • Cornices could break further back than expected and may trigger avalanches on drifted slopes below.
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

Solar warming will cause a heightened danger of loose wet avalanches during the middle of the day on sunny slopes in sheltered terrain.

weather

Strong high pressure along the West Coast will cross the Great Basin this weekend. High pressure will remain in place through at least the middle of next week. It'll be sunny today, with a 8500' high temperature of 27 F and a 15 to 20 mph northwest wind. It will be clear tonight with a low temperature of 17 F and 15 mph northwest wind. Tomorrow will be partly sunny with a high temperature of 31 F and a 5 to 14 mph west-northwest wind.

general announcements

Check out this spectacular triggered avalanche from Thursday in Telluride Colorado.

Ajax from Caldera Creative on Vimeo.


Any time is a great time to practice companion rescue techniques with your partners. Companion Rescue Practice Video

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Your information can save lives. If you see anything we should know please help us out by submitting snow and avalanche observations. You can call us at 801-524-5304, email by clicking HERE, or include @utavy in your Instagram. In the Logan Area you can reach me at 435-757-7578

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

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.