Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Monday - February 20, 2017 - 6:06am
bottom line

There is a very solid MODERATE avalanche danger in steep, upper elevation, wind exposed terrain where newly formed wind slabs and fresh drifts up to 18" deep exist on the leeward sides of ridge crests and terrain features. Once triggered, these slabs will be large enough to pack a punch. Suspect any steep slope with recent deposits of wind drifted snow. There is also a MODERATE danger for triggering a storm snow avalanche on all aspects, at upper and mid elevations on slopes steeper than about 35 degrees. Storm snow may run as a loose, dry sluff, or cohesive soft slab. And finally, with daytime heating, there will be a MODERATE danger for loose, wet avalanches on sun exposed slopes.




special announcement

Longtime local skier Craig Bigler lost a ski in the North Woods on Thursday. If you run across it please give him a call at 435-260-1007.

current conditions

A decent storm over the weekend brought up to a foot of medium density snow to the mountains and powder conditions on Sunday were excellent. Snow totals varied widely however, and you need to gain elevation to gain depth. Geyser Pass, and the Trans - La Sal trailheads only had a few inches of snow, while Gold Basin had 9" on the stake. Southeast ridge top winds blew in the 20-25 mph range for most of the storm with gusts into the 40's, but below tree line they were mostly light. By Sunday evening they had shifted to the NW averaging 15-20 mph.

In my travels on Sunday I didn't see any obvious signs of instability such as cracking in the snow surface, but I did find wind fresh wind drifts up to 18" deep. I also dug a pit on a NE aspect just below treeline at 11,000' and found a reactive layer of weak, faceted snow that had formed near the snow surface prior to the storm. Distribution of this weak layer varies, but a quick pit, even dug with your hand, will tell you if it is there.

For recent observations go here.

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

Storm totals and temperature in Gold Basin. (10,000')

Snow totals, temperature and snow/water equivalent at the Geyser Pass Trailhead. (9600')

recent activity

Lack of visibility prevented a good look around in the high country on Sunday, but I expect there were some natural storm snow releases on steep, upper elevation northerly aspects. If you observe any of these in your travels, please let me know by SUBMITTING OBSERVATIONS. Thanks!

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

Expect to find recently formed wind slabs and fresh drifts up to 18" deep in upper elevation, wind exposed terrain. Look for smooth, rounded deposits of wind drifted snow on the leeward sides of ridge crests and terrain features, and avoid steep slopes that have a "fat" appearance to them. In some cases, ridge crests have been scoured on both sides and loading has occurred farther down slope. Take extra care on these slopes, especially if they are convex, as they can lure you down beyond the point of no return.

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

Instabilities may linger in the storm snow for another day or two, particularly on slopes that have a weak faceted layer underneath. Loose, dry sluffs or cohesive soft slabs may be triggered. Continue to mind your slope angle, put in some cuts on test slopes, and take a minute to dig down and look for the underlying weak layer.

Avalanche Problem 3
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

As the sun pokes out today we can't overlook the potential for loose, wet slides in the surface snow on sun exposed slopes. Look for signs of instability such as roller balls or pinwheels, and get off steep slopes if they become sloppy.

weather

Washington's Birthday

Scattered flurries before 7am. Mostly sunny, with a high near 34. Breezy, with a north wind 5 to 10 mph becoming west southwest 15 to 20 mph in the afternoon. Winds could gust as high as 30 mph.

Tonight

Scattered flurries before midnight, then isolated snow showers after 1am. Mostly cloudy, with a low around 27. Breezy, with a west wind 15 to 25 mph, with gusts as high as 40 mph. Chance of precipitation is 20%.

Tuesday

Scattered flurries before 7am, then a slight chance of rain and snow showers after noon. Partly sunny, with a high near 37. Breezy, with a southwest wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.

Tuesday Night

Scattered snow showers, mainly after 11pm. Mostly cloudy, with a low around 26. Breezy, with a west southwest wind 20 to 25 mph, with gusts as high as 35 mph. Chance of precipitation is 30%.

Wednesday

A 10 percent chance of showers after 5pm. Mostly sunny, with a high near 37. Breezy, with a southwest wind 20 to 25 mph, with gusts as high as 35 mph.

Wednesday Night

A 40 percent chance of snow showers, mainly after 11pm. Mostly cloudy, with a low around 18. Breezy.

Thursday

Snow showers likely, mainly before 11am. Cloudy, with a high near 22. Breezy. Chance of precipitation is 70%.

general announcements

Road conditions: Expect to find a few inches of snow on the road at the upper end with somewhat sloppy an muddy conditions down low.

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The information in this advisory is from the US Forest Service which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.