Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Friday - February 23, 2018 - 6:29am
bottom line

The avalanche danger is CONSIDERABLE today on steep slopes that face NW-N-E right around treeline and above, especially on slopes that have recent deposits of wind drifted snow. Human triggered wind slabs, and deeper persistent slab avalanches up to 3' deep are likely in these areas. Backcountry travelers need to practice cautious route finding and make conservative decisions. Expect the danger to increase during the day as new and drifting snow make conditions more sensitive. The avalanche danger is MODERATE below treeline.




special announcement

Episode 5 of the UAC podcast "To Hell in a Heartbeat - A Conversation With Tom Diegel and Matt Clevenger About the 12.26.08 Full Burial on Little Water" is live. Matt and Tom talk about the avalanche documented in To Hell in a Heartbeat. Check it out on ITunes, Stitcher, the UAC blog.​

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current conditions

3-5" of snow has fallen since yesterday bringing our total since Monday up to about 15". SE winds overnight averaged 20 mph along ridge tops with gusts as high as 40, and it's 10 degrees at 10,000'. Soft settled powder conditions exist below treeline while above winds have scoured surfaces and drifted snow on to leeward slopes. The snowpack is still thin but we now have a skiable and rideable base with 42" on the ground at 10,000' in Gold Basin. Use caution and tread lightly as there are many obstacles lying just below the surface.

Base depth in Gold Basin: 42" Base depth at Geyser Pass Trailhead: 30"

New snow totals in Gold Basin.

Snow totals at the Geyser Pass Trailhead, (9600')

Wind, temperature, and humidity on Pre Laurel Peak (11,700')

Road conditions to Geyser Pass Trailhead: Grand County plowed on Tuesday. The road will be snowpacked with possibly a few inches accumulating today. 4wd is recommended.

Grooming conditions: Trails were last groomed through Gold Basin on Tuesday. They will be covered with 3-5" of snow today.

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

Little by little we continue to add weight to our relatively fragile snowpack. I haven't heard any reports of collapsing this week, but stability tests continue to show propagation on weak, sugary, faceted snow at the base of the snowpack. As we continue to add snow we grow closer to tipping the balance and the additional weight of a skier or rider is all that is needed on many slopes. The danger for triggering a persistent slab avalanche up to 3' deep is greatest on steep slopes, right around treeline and above, that face NW-N-E, especially if these slopes are overloaded with recent deposits of wind drifted snow. Human triggered avalanches remain likely in these areas. Addtional snow today and tonight will continue to keep the pressure on the snowpack.

The snowpit below illustrates the unstable base we are dealing with. An extended column test produced propagation failure on weak, faceted snow at the ground. ECTP 21
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

Blowing and drifting snow continue to be the order of the day. Southerly winds throughout the week have created wind slabs in upper elevation, wind exposed terrain. Older, harder slabs, covered by more recent snow exist further down slope, while recent fresh drifts continue to form on the leeward sides of upper elevation ridge crests and terrain features. On Wednesday I was able to crack out several drifts and this trend will continue today with more snow and wind in the forecast. Backcountry travelers should avoid any slope where the snow has a smooth, rounded appearance, or where you can detect recent deposits of wind drifted snow. The danger is greatest on steep terrain right around treeline and above that faces NW-N-E. In these areas, a triggered wind slab has the very real potential to step down causing a deeper and more dangerous persistent slab avalanche.

Frequent cracking in the snow surface indicates wind slab development.

weather

It's going to be a cold, snowy, windy day in the mountains. 10,000' temps will be in the mid teens but wind chill values will make it feel well below zero. Southwest winds will be on the increase averaging 20-25 mph. 3-5" of snow are possible today with showers lingering overnight.

general announcements

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This information does not apply to developed ski areas or highways where avalanche control is normally done. 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 occur.