Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Tuesday - November 29, 2016 - 7:00am
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The avalanche danger remains CONSIDERABLE on slopes that have recent deposits of wind drifted snow. The mountains have received over two feet of snow since Sunday, and things need time to adjust and stabilize. The danger is greatest above tree line on slopes that face NW-N-E, but all steep terrain should be approached with caution.




special announcement

Grand County will be plowing the road this morning. The gate will be closed while plowing is in progress. Expect a road opening between 10:30 and 11:00 a.m.

current conditions

The snow train keeps delivering and we picked up another 10" of light density snow in the past 24 hours, most of that coming in after 4:00 p.m. yesterday afternoon. This brings snow totals since Sunday up to 17" at the Geyser Pass Trailhead, and 27" in Gold Basin. Winds during this latest northwest flow event have been remarkably well behaved averaging 5-15 mph. They picked up around 5:00 a.m. and are currently blowing from the north in the 20-30 mph range. It's a very frigid 2 degrees not counting wind chill on Pre Laurel Peak, and 10 degrees at the Geyser Pass Trailhead.

In my travels yesterday I found excellent powder conditions over a supportable base. But the snow pack was still quite shallow, and dead fall still posed a problem in wooded areas. Above tree line the snow was more wind affected with southerly aspects showing signs of scouring, while northerly aspects were looking wind pretty loaded.

Got winter?

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

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

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

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 slabs formed on Sunday are stabilizing and are now more stubborn to trigger. However, in my travels above tree line yesterday, I was still able to crack out some fresh drifts along ridge crests. And peering farther down slope I could see smooth, rounded, characteristic pillows of wind deposited snow that looked pretty ominous. Avoiding slopes that look like that will be key today. Also look for signs of collapsing or cracking in the snow surface. Areas of greatest concern are slopes steeper than 35 degrees above tree line that have a NW-N-E aspect.

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

Today you may find some sensitivity in the new snow in the form of loose sluffs, or soft slabs. Even a little wind will make this snow more cohesive, and a relatively small slide starting in a large catch basin could translate to a lot of snow. Today is a good day to avoid being underneath big wind exposed terrain. Areas like Tele Gold and under the NE face of Tukno come to mind.

Avalanche Problem 3
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

The snowpack has received a significant amount of new snow over the past two days and in some areas this may equate to enough of a load to affect buried weak layers. Areas where you are most likely to encounter a persistent slab problem are on steep, northerly facing aspects at mid to upper elevations. Digging a snowpit, and performing a stability test is the only way to ascertain whether or not this problem exists, and this practice is highly recommended before venturing on to steep, avalanche prone terrain.

I have found this same sheeri in several snowpits on northerly aspects between 10,500' and 11,000' It appears to be a buried facet layer that formed near the old snow surface. Though not particularly reactive, it's there, and something to pay attention to.

weather

Today

A chance of snow before 11am, then a chance of snow showers, mainly between 11am and 4pm. Areas of blowing snow after 11am. Patchy fog before 10am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 15. Wind chill values as low as -10. North wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 50%. Total daytime snow accumulation of less than one inch possible.

Tonight

Partly cloudy, with a low around 7. North wind 5 to 10 mph.

Wednesday

Mostly sunny, with a high near 18. West northwest wind around 10 mph.

Wednesday Night

Mostly cloudy, with a low around 11. West wind 5 to 10 mph.

Thursday

A 20 percent chance of snow after 11am. Mostly cloudy, with a high near 17. West northwest wind 5 to 10 mph.

Thursday Night

A 30 percent chance of snow, mainly after 11pm. Mostly cloudy, with a low around 8.

Friday

A 40 percent chance of snow. Partly sunny, with a high near 16.