Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Friday - January 1, 2016 - 7:06am
bottom line

MODERATE (level 2): Heightened avalanche conditions exist in the backcountry, especially in drifted terrain at upper and mid elevations. Although conditions are becoming more stable, you still might trigger a dangerous deep slab avalanche in some areas, most likely from an area on a steep slope where the snow is shallow or rocky. Avalanches might be triggered remotely, from a distance or possibly from below. Evaluate the snow and terrain carefully and continue to practice wise backcountry travel protocols.




current conditions

The snow on most slopes appears to be stable, but the snow structure is poor and you still might trigger dangerous avalanches in some areas. A couple inches of very light snow yesterday only improved riding conditions in the backcountry. You'll find nice smooth settled powder riding conditions across the zone, and cold temperatures are keeping the snow nice and soft, even in the sun. It's easy to break trail since you don't sink in very deeply. You can ride almost anywhere, but you should be cautious in avalanche terrain because you still might trigger a large and dangerous avalanche, most likely from an area where the snow is thin or rocky.


We're keeping an eye on the snow surface these days, since weak layers commonly develop on or near the snow surface during high pressure conditions. We watched as V Feathery surface hoar or frost crystals grew on the snow surface during the day yesterday. (12-31-2015)


The Tony Grove Snotel at 8400' reports an inch of new snow from overnight and 6 degrees. The station reports 20 inches of settlement in the last week (since Christmas Eve), and there's now 50 inches of total snow, containing 99% of average water content for the date. It's 5 degrees at the 9700' CSI Logan Peak weather station, which is showing easterly winds averaging close to 30 mph with a 41 mph gust this morning.


recent activity

Evidence of significant natural activity from last week's productive 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.

  • On 12/19 an experience local rider was caught and carried through trees, mostly buried, and trapped by 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 Saturday. 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

Winds from the overnight drifted light surface snow in exposed terrain, and shallow fresh wind slabs developed near ridge tops and in and around terrain features like gullies and rock outcroppings. These fresh slabs are likely to be small and generally manageable, but you should use caution in drifted terrain. Be especially aware of trees or other terrain traps below you. The weight of a smaller wind slab avalanche overrunning a slope below might trigger a larger and more destructive avalanche involving old weak snow.

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 in many areas and dangerous deep slab avalanches might be triggered from shallower areas on the slab today, 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

STATE WEATHER SYNOPSIS...AN UPPER LOW OVER THE WESTERN GREAT BASIN WILL REMAIN IN PLACE INTO SATURDAY. THIS WILL ALLOW A WEAK RIDGE TO PERSIST OVER THE EASTERN GREAT BASIN INTO THE WEEKEND. A SERIES OF WEAK WEATHER SYSTEMS WILL MOVE ACROSS THE AREA BEGINNING EARLY NEXT WEEK.

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.