Avalanche Advisory
Advisory: Provo Area Mountains Issued by Greg Gagne for Friday - January 26, 2018 - 7:27am
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Recent winds and storm snow have created a CONSIDERABLE hazard exists at the mid and upper elevations on slopes facing north through east for triggering a persistent slab avalanche. A CONSIDERABLE hazard also exists at the upper elevations for triggering a fresh wind drift.

Fortunately, there is plenty of safe, excellent riding today in the new snow on lower-angled terrain.




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current conditions

Temperatures range from the low to mid teens F, and winds are out of the west/northwest. Although winds have diminished since the passage of yesterday afternoon's cold front, they are gusting into the teens at mid elevations, and 20's and 30's at the upper elevations. At 11,000' winds are blowing in the 30's, with gusts into the 50's mph.

2-4" of new snowfall from late yesterday afternoon and overnight was reported from the Provo mountains.

The new snow will provide superb riding conditions today, especially on lower-angled terrain.

Although it is Salt-Lake centric, be sure to read our Week in Review highlighting avalanche activity and snowfall from this past week.

recent activity

No avalanche activity was reported from the backcountry on Thursday, with only a couple of observations from the few intrepid souls that ventured out. You can check out all field observations by clicking HERE.

Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

I just don't trust it. In the Salt Lake and Park City area mountains, at least five human-triggered slides occurred on steep north through northeast aspects this past week, with the most recent slide occurring this past Wednesday on Pointy Peak along the Park City ridgeline. These slides failed on faceted layers down 2-3', and were over 100' wide and running several hundred feet. Some of these slides were triggered remotely (from a distance), and one occured on a slope with nearly 20 tracks on it. Yesterday's strong west/southwest winds, as well as 6-8" of new snow (with 0.5" water) have put a new load onto these slopes, stressing these weak layers once again.

The aspects I am most concerned about are 9000' and above, facing north through east.

On Wednesday Drew spent time in the UFO Bowls on Timpanogas, finding a complex structure of faceted snow and crusts.

The video below is from field work Zinnia and I performed yesterday looking at the snowpack where the Pointy Peak avalanche occurred, highlighting the poor structure of a strong slab on top of weaker facets:

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

Yesterday's strong west/southwest winds created drifts at the mid and upper elevations. These drifts were hard, and ranged in depth from 6" to 18" along mid and upper elevation ridgelines. Although my partner and I were finding them to be stubborn and only cracking right around our skis, one observer reported them to be more sensitive. The new snowfall will cover these drifts, making them difficult to identify. These fresh drifts will primarily be found at the mid and upper elevations on aspects facing north through southeast. However, channeling around terrain features may have created deposits on almost any aspect.

Although I think the biggest issue with these fresh wind drifts is where they have overloaded persistent weaknesses on northerly aspects, drifts may also be sensitive where they also formed on top of weaker, low-density snowfall from this past week.

Westerly winds today will have fresh snow to work with, and will create new drifts, especially at the upper elevations.

weather

Today will be one to savor. Be sure to bottle it up as you'll want to crack it open in July. Partly sunny with high clouds and temperatures in the low teens at the mid and upper elevations, and rising into the low 20's F at the lower elevations. West/southwest winds gusting into the 20's mph and into the 30's at the upper elevations, likely exceeding 40 mph at 11,000'. We may get a trace of new snow.

Enjoy it while you can as temperatures warm this weekend, with riming possible.

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.