Avalanche Advisory
Advisory: Moab Area Mountains Issued by Eric Trenbeath for Friday - December 13, 2013 - 6:42am
bottom line

The bottom line is that a MODERATE avalanche danger exists on slopes steeper than about 35 degrees with a NW-NE aspect. There are still areas of CONSIDERABLE avalanche danger, on upper elevation steep slopes with a NW-E aspect where the potential exists to trigger a high consequence avalanche. Elsewhere, the avalanche danger is generally LOW.
current conditions

The mountains have been under clear skies and a gradual warming trend through the course of the week. This has had its effect on the snow surface and a mixed bag of surface conditions exists. WNW winds earlier in the week scoured and etched exposed upper elevations, while yesterday, a strong sun and warm temperatures finally had their way with southerly aspects and they will be crusted over today.In addition a new layer of surface hoar has developed. Settled powder still exists on northerly aspects below tree line and in sheltered areas. Winds were mostly light overnight, averaging 10 mph on Pre-Laurel Peak with gusts to 20 mph out of the SW. They swung around to the NW about an hour ago. The temperature is a balmy 18 degrees, and it will climb into the high 20's today. There is currently 22" on the ground at Geyser Pass Trailhead, and 36" in Gold Basin.
recent activity

.

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

With the wind slabs that formed over the weekend gaining strength, the buried, persistent slab has again become the main player. The existing snow pack structure is very weak with both mid level facets and basal facets at the ground. The recent wind slabs have added additional stress to the buried, persistent slab. Stability tests showed that the recent slabs are now bonding to the old snow surface, and are in effect, becoming part of the persistent slab. Sheer failure is occurring at the mid level facets that have formed at the bottom of persistent slab. What this means is that the potential exists to trigger a deep, and dangerous avalanche on steep NW-E facing aspects above about 10,500'. For pit profile pictures, go here: http://utahavalanchecenter.org/observations/19045
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

It still remains possible to trigger one of the wind slabs that formed last weekend. Though isolated, this problem exists at extreme upper elevations on steep slopes with a NW-E aspect. This problem is most acute near ridge crests, underneath rock bands, and on the lee sides of terrain features on upper elevation, exposed terrain. In addition, NW winds may have formed slabs on SE aspects at extreme upper elevations.
weather

Sunny skies are on tap today with high temperatures in the upper 20's. Winds will average 10-15 mph from the WNW. Expect more of the same with increasingly warmer temperatures over the weekend. Dry weather continues into next week with our best chance at a change coming by next Thursday or Friday.
general announcements

OBSERVATIONS: If you are out and about in the mountains, I'd love to know what you are seeing. Please submit your observations here: http://utahavalanchecenter.org/node/add/observations?destination=bc_obs_3

LUNA Information: There will be a meeting for all interested grooming volunteers on Saturday, December 14, at 8 a.m. at the MARC.

ROAD CONDITIONS: Plow crews will be initiating road closures during plowing this season due to conflicts with traffic. The plan is to call me the day before they plan to plow so I can post it in this advisory. This closure could take up to two hours so please plan accordingly. Do not expect plowing over the weekend. San Juan County does an excellent job keeping our road open but please keep in mind that their first priority after a storm is to open roads in and around populated areas.