Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Wednesday - February 3, 2016 - 7:19am
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CONSIDERABLE (level 3): Dangerous avalanche conditions remain on drifted slopes in the backcountry. Careful snowpack evaluation, cautious routefinding, and conservative decision-making will be essential again today. You are most likely to trigger avalanches on drifted upper elevation slopes, and large and dangerous triggered deep slab avalanches remain possible on some slopes steeper than about 30 degrees with weak sugary or faceted snow near the ground.




special announcement

Sad news of an avalanche fatality in the backcountry near The Canyons in Park City. A 50-year-old lone backcountry skier was caught and buried by an avalanche on Sunday. His body was located by beacon search yesterday afternoon (2-2-16). Here is our Preliminary Accident Report.

current conditions

Monday's wind jacked the snow in exposed terrain, and there's a wide variety of wind effected snow ranging from stiff thick slabs, solid wind boards, thin wind skins or crusts, scoured off areas, and on slopes facing the wind a bit of sastrugi . I found nice fast shallow settled powder on a solid rain-crust at lower elevations yesterday, with the best smooth turning conditions in low angled terrain. The settled and re-crystallized snow on sunny slopes was still nice and soft in the afternoon, but thin sun-crusts probably formed on the surface overnight in places. There are still areas with dangerous avalanche conditions, with our main concern the possibility of deep slab avalanches on drifted upper elevation slopes with shallow overall snow cover.

The temperature is 9 degrees and there's an inch of new snow from overnight at the 8400' Tony Grove Snotel. There's 75 inches of total snow, containing 106% of average water content for the date. The 9700' CSI Logan Peak weather station reports 2 degrees and the wind sensor still appears rimed. The UDOT Hwy 89 summit weather station reports 11 degrees and moderate wind from the northwest overnight.
recent activity

My party noticed a fresh deep slab avalanche on Monday in the Oscar Mayer slide path in Logan Dry Canyon. A local observer skied the line on Sunday afternoon before the east winds picked up Sunday night, and the sizable avalanche must have occurred overnight or early in the morning of February 1. Report is HERE

A fresh natural deep slab was observed in Logan Dry Canyon (Oscar Mayer) on February 1. It was likely a natural caused by a period of east wind overnight, which drifted snow onto the slope, overloading weak faceted snow or depth hoar. (Glew, 2-1-2016)

Looks like a fairly widespread natural avalanche cycle over the weekend, with numerous large and long running avalanches visible in the generally east facing avalanche paths in the Wood Camp Area and in the Wellsville Range above the towns of Mendon and Wellsville, and south, above Hwy 89/91 (Sardine)

A hiker on snow-shoes triggered and may have been caught in a loose avalanche at the mouth of Logan Dry Canyon Saturday. And, it looks like a pedestrian sledder might have taken a similar ride in loose snow at the very bottom of Green Canyon.

There were several (apparently manageable) human triggered avalanches in the Logan Zone last week. These on north through east facing upper and mid elevation slopes were around a foot deep and up to about 50' wide.

A video posted on Facebook from a large sled triggered avalanche (1-19-16) in Christmas Tree Bowl is .....HERE

***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

Persistent wind slab avalanches including stiff drifted snow and failing on preexisting weak surface snow are still likely in steep wind exposed terrain today.

  • In some areas the weekend snow fell on and preserved weak surface snow consisting of small sugary or faceted grains or feathery frost crystals called surface hoar. The buried weak snow may turn out to be a longer lasting persistent weak layer.
  • East winds overnight easily drifted the weekend's fresh snow at upper elevations on Sunday night.. The winds veered back around from the west and northwest on Monday, drifting significant quantities of light snow into deposition areas. Watch for and avoid slopes with recent deposits of drifted snow, particularly near ridge tops and in and around terrain features like gullies, sub-ridges, scoops, and rock outcroppings.

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

Heavy snow over the weekend overloaded a complex snowpack, with existing buried persistent weak layers in some areas and still weak basal layer depth hoar in others.

  • Triggered deep slab avalanches are possible in some areas today. Weak snow structure exists mainly in areas where the total snow is 3' deep or less, including in shallow rocky upper elevation terrain as well as many areas at lower and mid elevations where you still sink through all the way to the ground in boots or off the sled. I'm finding propagation in most of my snowpit tests these days, with failures common in loose sugary faceted snow in the basal layers.
  • In areas with particularly poor snow structure, the weak faceted snow in the basal layers of the snowpack appears to have been reactivated by the added weight of drifted accumulations from this weekend's snow. Dangerous and destructive​ deep slab avalanches involving old snow and failing on sugary faceted snow or rock salt-like depth hoar are possible, especially in areas with shallow overall snow cover.

***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 trigger avalanches remotely, from a distance or worse, from below!
weather

A weak disturbance will graze northern Utah today and there's a good chance for snow showers this morning. It'll be cloudy but some clearing and a bit of sun is possible this afternoon. High temperatures at 8500' are expected to be around 14 degrees, there will be a moderate west wind (15-20 mph), and we could see an inch or two of accumulation. Snow will redevelop late tonight, with low temperatures around 7 degrees and continuing west wind. An inch of snow is possible late. Snow is likely tomorrow in the mountains with continuing sustained west wind, a high temperature near 20 degrees, and 3 to 5 inches of accumulation possible. A strong high pressure system will build over the area for the end of the week..
general announcements

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.