Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - February 4, 2017 - 7:09am
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There is a CONSIDERABLE danger of wind slab avalanches at upper elevations and of wet avalanches at low elevations. Triggered avalanches are likely and naturals possible in the backcountry today. Drifting from sustained and increasing southwest wind is creating dangerous wind slab avalanche conditions in exposed upper elevation terrain. Rain on already saturated snow at low elevations is causing dangerous wet avalanche conditions on low elevation slopes. Carefully evaluate the snow, be conservative in decision making and route finding, avoid and stay out from under steep drifted slopes and those with saturated snow.




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current conditions

The 8400' Tony Grove Snotel reports 5 inches of new snow with .6" SWE ‚Äč(Snow Water Equivalent) in the last 24 hrs. It's 29 F and there is 96" of total snow containing 151% of average SWE. It's 23 F at the CSI Logan Peak weather station at 9700', and the wind is whipping from the south at 29 mph, gusting to 50 mph. Triggered wind slab avalanches are likely in drifted terrain and naturals are possible. Yesterday the snow on low elevation slopes was soggy from warmth, and rain today could create dangerous wet avalanche conditions on slopes with saturated snow.


Roller balls and pinwheels like these from Tab Hollow yesterday are precursors to wet avalanche activity.


recent activity

It's been more than a week since any significant avalanches have been reported in the Logan Zone, but several small loose wet avalanches were observed yesterday in Logan Canyon.

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
  • Drifting from increasing southwest winds today will continue to create fresh wind slabs and build cornices in exposed terrain.
  • 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 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Rain on already wet snow at low elevations will cause an increasing danger of wet avalanches. Natural sluffs entraining loose wet snow are likely at lower elevations, and dangerous triggered wet slab avalanches are possible on slopes with buried persistent weak layers. Avoid and stay out from under steep slopes with saturated 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

Triggered persistent slab avalanches around 2 feet deep are possible in isolated mid-elevation terrain.

  • Buried surface hoar exists mainly in sheltered mid and lower elevation terrain, but is found on east, north, and west facing slopes.
  • A weak layer of small facets on top of a sun-crust still plagues some sunny mid elevation slopes.
  • You will have to dig down into the snow a couple feet to find the buried persistent weak layers.



    I found saturated surface snow on all aspects and buried surface hoar about 1' deep in Tab Hollow yesterday (2-3-17).

weather

The National Weather Service in Pocatello ID has continued a Winter Storm Warning for the mountains in Franklin and Bear Lake counties. A weak weather system will exit the area today. After a brief break on Sunday, an active weather pattern will continue for much of next week. Snow showers are likely today, with 2 to 4 inches likely. The high temperature at 8500' is expected to reach 33 F, with west winds 20 to 25 mph. Snow is possible tonight, with a low temperature around 26 F, west winds 15 to 20 mph, and 1 to 2 inches of snow. Showery snow may continue through Sunday and Sunday night, with 8500' temperatures hovering around freezing and 2 to 4 inches possible. A bit stronger system will pass over the zone on Monday, with 3 to 7 inches of snow possible.

general announcements

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

If you sign up for AmazonSmile and designate the Utah Avalanche Center as your favorite charity, they will donate a portion of everything you spend to the UAC. It doesn't cost you a penny and we'd really appreciate the help.

Discount lift tickets for Beaver Mountain, Snowbasin, Powder Mountain, and the Central Wasatch resorts are donated by the resorts to benefit the Utah Avalanche Center. Details and order information here.

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.