Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - January 21, 2017 - 6:19am
bottom line

East winds calmed overnight, but heightened wind slab avalanche conditions exist on drifted upper elevation slopes. Loose, long-running sluffs entraining light new snow are likely in steep terrain. Snow and strengthening west-northwest winds will cause the avalanche danger to rise and become more widespread today. Evaluate the snow and terrain carefully and avoid steep drifted slopes.




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current conditions

The Tony Grove Snotel at 8400' reports 19 F and 2 more inches of light snow in the last 24 hrs. There is 88 inches of total snow containing 156% of average SWE (Snow Water Equivalent). It's 15 F at the CSI Logan Peak weather station at 9700', with a 8 mph wind from the east-southeast. Easterly winds calmed last night after a couple hour bump with wind speeds in the mid twenties yesterday evening. We found nice powder riding yesterday, with an inch or two of new snow on re-crystallized surface snow and surface hoar. There is a sun-crust of variable thickness on slopes facing even a little southward. An inch or two of light new snow capped and preserved delicate surface hoar and weak sugary surface snow, and we'll have keep an eye on this layer as more snow stacks up on it in the next few days...


Surface hoar was widespread in the Logan Zone, and it's now buried and preserved by a couple inches of light snow.

recent activity

No new avalanches have been reported since last week's widespread, natural avalanche cycle.

Large, natural avalanches from last week in the Wellsville Range above Mendon.
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

East winds yesterday evening created a heightened danger of wind slab avalanches in exposed upper and mid elevation terrain. Increasing and gusty northwest wind today will cause the danger to rise and become more widespread.

  • Drifts are forming on weak surface snow consisting of surface hoar and/or small-grained sugary faceted snow, and fresh wind slabs will be sensitive to human triggering.
  • A few inches of fresh powder could be hiding drifts that formed late yesterday.
  • Wind slabs made up of stiffer drifted snow are often 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 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

Deep slab avalanches, failing on buried weak layers, are unlikely but possible.

  • Large, natural avalanches stepping into old snow were common during last week's storm at all elevations.
  • Weak layers of faceted snow exist above and below rain-crusts at mid and lower elevations.
  • The snow is weakest in rocky terrain where it's thin or shallow. Thursday in Logan Canyon's East Banks we found a slope plagued by depth hoar near the ground. Tests on the mid elevation west facing slope showed a propagating failure near the ground, but it was difficult to initiate.
  • Currently our deep slab avalanche problem is low probability - high consequence, meaning you're unlikely to trigger one, but if you get caught, you could get killed or seriously injured.
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
  • Sensitive soft slabs involving the new snow and failing on buried surface hoar are possible in sheltered terrain, especially as more snow accumulates today. Avalanches will become more likely during periods of heavy snowfall.
  • Loose avalanches or sluffs entraining light new snow were common in steep terrain in the mountains above Salt Lake City yesterday, and natural sluffing is ongoing this morning. Get out of the way of your companions in steep terrain, and watch for natural sluffs during periods of heavy snowfall.
weather

The active weather pattern will continue across the region, with a series of weather systems crossing the area through the first half of next week. Expect 3 to 7 inches of snow today, and a high temperature at 8500' of 27 degrees F. West-northwest winds will increase this morning, with 25 to 30 mph average wind speeds and gusts of around 40 mph this afternoon. 3 to 5 inches of snow is expected tonight, with winds veering from the southwest and a low temperature around 16 F. A few inches of snow is likely tomorrow, with a high temperature around 28 F and 15 to 20 mph south winds. The storm will intensify Sunday night and last through Monday, with strengthening south and west winds and 8 to 16 inches of snow possible by Monday evening.
general announcements

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

The National Avalanche Center just released their Avalanche Problems Explained video... Not all avalanches are made the same. As a result, travel and decisions in avalanche terrain are influenced by the kind of avalanche you expect to encounter. Watch HERE

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.