Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Sunday - December 4, 2016 - 7:29am
bottom line

The avalanche danger is MODERATE on steep upper elevation slopes that have recent deposits of wind drifted snow. There is also a MODERATE danger for triggering a deeper, persistent slab in upper elevation, north facing terrain.

Elsewhere the avalanche danger is generally LOW.




special announcement
current conditions

Northerly ridge top winds have been on the increase since about midnight last night and are currently blowing in the 20-30 mph range and mountain temperatures are in the low teens. Good powder conditions over a supportable base can still be found below tree line and in sheltered alpine bowls, but the early season snow pack remains shallow, and rocks and dead fall lurk just beneath the surface. Above tree line, winds have affected the snow surface in exposed areas, and some south facing slopes have developed a thin crust. Average snow depth is 24"-36".

Storm totals and temperature 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')

From nothing on the ground two weeks ago to this. Not bad for early December.


Snow is wind affected above tree line.


But drop down below, and it's powder!

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

There is plenty of loose snow available for transport. and with winds on the rise you will need to be alert to freshly formed wind slabs on the lee sides of ridge crests and terrain features at upper elevations. Look for smooth, rounded deposits of wind drifted snow, and be alert to signs of instability such as cracking or collapsing in the snowpack.

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

So far we have the makings of what Western Uintah forecaster Craig Gordon is calling a "designer snow pack." With virtually no snow on the ground prior to the first 9" storm on 11-16, we've had a succession of storms pile up in short order that have given us an instant snow pack 24"-36" deep. The snow pack is "right side up" meaning it gets progressively denser near the bottom. Of note are some early stage basal facets, or sugary weak snow near the ground. Though not currently reactive, their development will likely increase over the next week with the coming cold temperatures and periodic clear nights. I've also been able to tease out a weak layer that sheers, but doesn't propagate mid way down in the pack. These things aren't currently huge red flags, but you'll want to investigate the snow pack before committing to steep, upper elevation, northerly facing terrain.

Sheers like this continue to show up but they aren't propagating.

weather

Dry and seasonally cool weather is expected to prevail today. The next storm system remains on track for the first half of the work week with the main impact being very cold temperatures beginning Tuesday up north and spreading south for Wednesday and Thursday thanks to arctic air being steered over the region. This weather system is trending drier and less-organized, so snow production will likely be on the lighter end. Nevertheless, the northern and central mountains could still see amounts approach a foot over a 2-day period ending Tuesday.

Today

Mostly sunny, with a high near 28. Northwest wind around 15 mph, with gusts as high as 25 mph.

Tonight

Partly cloudy, with a low around 17. Breezy, with a west southwest wind 15 to 20 mph, with gusts as high as 30 mph.

Monday

Mostly sunny, with a high near 23. Breezy, with a west wind 15 to 20 mph, with gusts as high as 30 mph.

Monday Night

Partly cloudy, with a low around 11. Breezy, with a west southwest wind 15 to 20 mph.

Tuesday

A 40 percent chance of snow. Partly sunny, with a high near 19. Breezy, with a west southwest wind around 20 mph, with gusts as high as 35 mph.

Tuesday Night

A 40 percent chance of snow. Partly cloudy, with a low around -4.

Wednesday

Sunny and cold, with a high near 8.

general announcements

The road to Geyser Pass Trailhead is plowed and clear.

Grooming of cross country trails has commenced for the season. Kirstin and Travis got things packed out and rolled into Gold Basin and through the lower meadow on Thursday.