Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Monday - January 4, 2016 - 6:56am
bottom line

MODERATE (Level 2): Heightened wind slab avalanche conditions exist on recently drifted slopes, and dangerous though unlikely deep slab avalanches remain possible and might be triggered from a shallow or rocky area. Evaluate the snow and terrain carefully and continue to avoid steep drifted slopes at upper elevations.




current conditions

We've noticed the rapid development of small grained near surface facets and frost crystals or surface hoar on the snow surface in the past few days. Once buried, these can become thin persistent weak layers. Sustained southeast winds Friday continued through the weekend, scouring snow out of east facing avalanche paths and damaging nice settled powder at upper elevations. Drifting created sensitive and now stiffer and more stubborn wind slabs on top of weak surface snow, and over the weekend a few parties in different areas triggered small wind slabs or observed natural avalanches. It's 29 degrees at the Tony Grove Snotel at 8400' and there's 47 inches of total snow, containing 97% of average water content for the date. I'm reading 27 degrees at the 9700' CSI Logan Peak weather station, which is showing more southerly winds, still averaging in the mid twenties this morning.

Sustained east and southeast winds in the past few days jacked the nice snow in exposed terrain across the zone. (Pagnucco 1-1-16)
recent activity

***DB Bowl Avalanche: Here's a new video looking at a recent natural avalanche in Logan Dry Canyon.

Evidence of significant natural activity from the productive pre-Christmas storm is widespread across the Logan Zone. Most of the natural avalanches occurred early in the storm, but there are also a few that appear to be a bit more recent and might have been remote triggered...

Parties on New Years Day reported significant drifting and observed fresh natural wind slab avalanches. Over the weekend, riders triggered several manageable wind slabs in the Providence Canyon and Tony Grove Area. These were all around 30 feet wide and 8"-12" deep.

Pictures of triggered but manageable wind slab avalanches from the weekend. (1-2-16 Tony Grove, Flygare 1-1-16 Millville Peak, Wolford)

Last Year, 2015:

  • On 12/19 an experience local rider was caught and carried through trees, mostly buried, trapped, injurred, and rescued from an avalanche he triggered above the Tony Grove Campground. Video Report
  • On 12/20 a skier remote triggered a large Deep Slab avalanche high on the south rim of lower Logan Canyon.
  • I observed several large more recent avalanches in the upper Providence Canyon area on 12/26. I think these were Christmas Eve naturals, but they might've been remote triggered, unseen by riders in limited visibility. Video Report

***To view our updated list of backcountry observations and avalanche activity from around Utah, go to our observations page

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 and southeast winds Friday and over the weekend drifted light surface snow in exposed terrain, and fresh wind slabs developed near ridge tops and in and around terrain features like gullies and rock outcroppings. The wind slabs formed on weak sugary or faceted snow that was on the snow surface at the end of last year. Several natural and triggered wind slab avalanches were reported in the Logan Zone Friday and Saturday, and you could still trigger wind slabs in drifted terrain today. Today's wind slabs might be a bit larger and harder than they were over the weekend, and it'll be wise to avoid steep drifted terrain.

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 very weak snow was overloaded by a few feet of heavier drifted snow last week creating an unstable situation, with a cohesive slab sitting on weak sugary or faceted snow. Settlement and cold temperatures have helped to stabilize the snow and in many areas the slab layer is so thick that it would be very difficult for riders to trigger, but heightened avalanche conditions persist. Dangerous deep slab avalanches might be triggered from shallower areas on the slab, especially in outlying drifted terrain at upper and mid-elevations.

***Pay close attention to signs of unstable snow like recent avalanches, whumpfing, and shooting cracks, and be willing to reevaluate your plans. In these conditions you could still trigger avalanches remotely, from a distance or worse, from below!

weather

Expect mostly cloudy conditions in the mountains today, with 8500' high temperatures around 34 degrees and a moderate south wind. Snow is likely tonight, with 1 to 2 inches of accumulation possible, a low around 21 degrees and southwest winds. A few more inches of accumulation is possible with a continued weak but moist weather pattern Tuesday and on into Wednesday...
general announcements

The CROWBAR backcountry ski race will be Saturday January 30. More info at http://CrowbarSkiRace.org.

Please submit snow and avalanche observations from your ventures in the backcountry HERE. You can call us at 801-524-5304 or email HERE, or include #utavy in your Instagram or Tweet us @UAClogan. To report avalanche activity in the Logan Area or to contact the local avalanche forecaster call me, Toby, at 435-757-7578. 

I'll update this advisory throughout the season on Monday, Wednesday, Friday, and Saturday mornings by about 7:30

This advisory is produced by the U.S.D.A. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist.