Avalanche Advisory
Advisory: Provo Area Mountains Issued by Greg Gagne for Friday - February 10, 2017 - 7:13am
bottom line

A CONSIDERABLE hazard exists at the low and mid elevations for wet loose avalanches. Travel on or underneath steep slopes at the low and mid elevations is not recommended today.

A MODERATE hazard exists for fresh wind drifts above 9000'. Strong winds may deposit drifts on all aspects and well down off of ridgelines. Cornices will only grow larger today - stay well back from the edge of corniced ridge-lines.

Forgive the oft-used cliche, but unusual weather breeds unusual avalanches.




special announcement

Wasatch Backcountry Skiing Weather: Friends of the UAC President Steve Achelis has done it again: check out his one-stop-shop page here.

Know-Before-You-Go (KBYG) tonight at 6:30 PM at Mad Dog Cyclery in Orem. Details can be found here.

current conditions

Strong winds and very warm temperatures highlight the current weather conditions this morning. Winds are out of the south and southwest and have been strong for at least the past 24 hours, with gusts in the 40’s mph at the mid elevations, and 50’s - 60’s mph at the upper elevations. A few stations reported overnight gusts of 70 mph or more.

Most mountain stations have been well above freezing for the past 36-48 hours. Temperatures in the Provo mountains currently range through the 40’s F.

Below is the 7 am update for Arrowhead Divide at 8200'


No precipitation recorded overnight.

Week in Review

4-6” of snowfall fell in the Cottonwoods and Park City mountains from Thursday Feb 2 through Saturday Feb 4, with some favored locations along the Park City ridgeline receiving upwards of 8”. Persistent winds also resulted in isolated human-triggered wind slabs releasing in upper elevations over the weekend.

Monday marked the beginning of a period of warm and very windy conditions with heavy, wet snowfall and a rain/snow line reaching 8000'. Snow and water totals by Wednesday included:

  • Salt Lake area mountains 6-8" snow with 1" water. As is often the case with this winter's storm track, Brighton fared the best with 17" of snow and 1.75" water.
  • Park City mountains 9-11" snow with 1" water.
  • Provo mountains 15" snow with 4.7" water. Much of the precipitation fell as rain at the lower and mid elevations. A significant natural cycle occurred at the upper elevations in the Provo mountains, as well as wet avalanches that went to the ground from both natural avalanches as well as through control-work.
  • Ogden mountains 10-17" snow with 3" water. The Ogden mountains had especially strong winds, gusting to over 80 mph, including Mt Ogden clocking in at 94 mph. Road closures included North Ogden Divide as well as SR158 leading to Powder Mountain.

Temperatures warmed significantly beginning on Wednesday, with overnight lows only dropping to the mid 30's F. A few natural avalanches were reported on Wednesday from cornice falls. On Thursday, the base of Alta reached 50 F, with many mid and upper elevations rising into the mid 40's F with increasing winds.

recent activity

Avalanche activity reported from Thursday were wet loose slides at the low elevations in Little Cottonwood Canyon in the Salt Lake mountains. This included a wet natural at the lower elevations in Coalpit Gulch, as well as a loose wet slide that overran the Great White Icicle ice climbing route. (Although the warm temperatures should currently classify it as a "dry-tooling" route.)

Shockingly few reports from the backcountry on Thursday. For the few that ventured out, reports highlighted damp snow as well as large pinwheels and rollerballs at the low and mid elevations. I found surprisingly decent ski and travel conditions above 10,000’, although sustained strong winds overnight at the upper elevations have likely changed that scenario.

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

I can't believe we are talking about a saturating, rain-on-snow event in early February. Unusual weather breeds unusual avalanches. The snowpack hasn't cooled in nearly 48 hours, and rain (possibly heavy at times) to 9000' will elevate avalanche concerns at the low and mid elevations with natural wet avalanches possible. Travel is not recommended on or underneath any steep slopes at the low and mid elevations today.

ROOF AVALANCHES continue to be a significant concern. Avoid being in the "runout zones" below a pitched roof.

GLIDE releases should be on your radar in the standard glide avalanche regions of Broads Fork, Stairs Gulch, and localized areas of Mill B south. Full-depth glide releases are notoriously unpredicatable, but rain and melt-water percolating down onto the smooth underlying rock slabs below is a classic contributing factor.

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

Strong winds from the south and southwest will drift any new snow and create sensitive wind drifts at the upper elevations. Although I am not expecting these drifts to be large, such strong winds can deposit snow on all aspects and well down off of ridgelines.

There are very large cornices adorning our mid and upper elevation ridgelines. Some of these cornices have released naturally, or have released with minimal human provocation. On Wednesday a skier unintentionally collapsed a large cornice fall along the Patsy Marley ridgeline in the Salt Lake mountains. Natural or human-triggered cornice falls may not only trigger an avalanche, but they also will involve very large blocks of snow. (Think of it like tumbling down a slope along with a fleet of small delivery trucks.)

Stay well back from the edges when traveling along corniced ridgelines.

weather

Rain at the low and mid elevations, and 2-5” of snow possible at the upper elevations.

Temperatures will remain warm today at the low and mid elevations, remaining in the 40’s F. Above 10000’ temperatures should cool as the day progresses, dropping to the upper 20’s F by sunset.

A much-needed cold front arrives this evening as the flow switches to the northwest and continued snowfall overnight.

general announcements

Remember your information can save lives. If you see anything we should know about, please help us out by submitting snow and avalanche conditions. You can also call us at 801-524-5304, email by clicking HERE, or include #utavy in your tweet or Instagram.

To get help in an emergency (to request a rescue) in the Wasatch, call 911. Be prepared to give your GPS coordinates or the run name. Dispatchers have a copy of the Wasatch Backcountry Ski map.

Backcountry Emergencies. It outlines your step-by-step method in the event of a winter backcountry incident.

If you trigger an avalanche in the backcountry, but no one is hurt and you do not need assistance, please notify the nearest ski area dispatch to avoid a needless response by rescue teams. Thanks.

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DAWN PATROL Hotline updated daily by 5-530am - 888-999-4019 option 8.

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UDOT canyon closures: LINK TO UDOT, or on Twitter, follow @UDOTavy, @CanyonAlerts or @AltaCentral

Utah Avalanche Center mobile app - Get your advisory on your iPhone along with great navigation and rescue tools.

Powderbird Helicopter Skiing - Blog/itinerary for the day

Lost or Found something in the backcountry? - http://nolofo.com/

Ski Utah mobile snow updates

To those skinning uphill at resorts: it is critical to know the resort policy on uphill travel. You can see the uphill travel policy for each resort here.

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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 exist.