Avalanche Advisory
Advisory: Ogden Area Mountains Issued by Drew Hardesty for Sunday - January 29, 2017 - 6:20am
bottom line

The avalanche danger today is MODERATE on all aspects and elevations. The danger for wet snow avalanches will rise to MODERATE with daytime warming. Human triggered avalanches are possible on many steep slopes today...and may be triggered from a distance.




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current conditions

Skies are partly cloudy with light to moderate northerly winds. The Ogden skyline gusts are in the 30s and 40s. Temperatures are in the mid to upper 20s. Sun and wind damage exist on the sunny aspects and in the open, exposed terrain, but excellent conditions remain in the sheltered terrain. With over 100" on the ground at the mid and upper elevations, the Ogden snowpack sits at 150-200% of normal. Coverage and conditions are some of the best in years.

recent activity

No new avalanches have been reported in the Ogden area backcountry for a few days; however, second hand reports are filtering in of human triggered avalanches just along the Logan/Ogden mountain divide. Similarly, just to the south in the Parley's/Big Cottonwood Canyon area, six human triggered avalanches occurred on Friday with two people caught and carried in these 2-4' deep and up to 800' wide avalanches. Observers are still noting collapses both to the north and south of the Ogden mountains, but this is not to say that it won't occur today.

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

This past week's persistent slab avalanches were triggered on a layer of buried surface hoar or on a layer of small, faceted crystals buried 2-4 feet deep. This layer is widespread in the Ogden area mountains though there are some places where it was destroyed prior to the storm. The buried surface hoar is most dangerous where it was sheltered from the wind and buried intact. It might catch you off guard as you descend into sheltered, lower and mid-elevation slopes or gullies. Though observers near Ben Lomond noted its presence Thursday and were unable to get propagation while performing stabiity tests, this type of weak layer is deceptive and takes a while to strengthen.

Because this weak layer can be coy, your best bet for finding it is to dig about 4 feet deep, perform stabilty tests like the ECT, and make sure it doesn't exist. Buried surface hoar does not behave like a typical weak layer so a lack of cracking, collapsing, or other obvious signs of instability does not mean slopes are stable. Tracks from other people are also not a guarantee of stability. If you are not interested in digging then the easy solution is to avoid being on, connected to, or underneath slopes steeper than 30 degrees.

Left: Observed buried surface hoar near Rodeo Ridge was unreactive to stability tests Thursday. (pc:M. Henderson)

Right: One of numerous avalanches failing on buried surface hoar or small facets on Monday in the Cutler Ridge area. (pc: B. Brandt)

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

There is plenty of snow available for transport and wind drifts should be considered suspect and avoided in steep upper elevation terrain. Drifts often appear rounded, scalloped, or otherwise textured and form in the lee of terrain features such as rocky outcrops and sub-ridges. These drifts may be more sensitive than usual as some of them may be siting on small surface hoar or granular faceted snow formed Thursday night.

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

Cold, dry snow under the heat lamp and with mountain temps rising into the mid 30s at 8500' will conspire to dampen the snow surfaces on the steep sunlit slopes. With prolonged dampening, both natural and especially human triggered wet avalanches will be likely with daytime warming. Please choose terrain to avoid the steep sun-drenched slopes by midday - particularly those above roads and infrastructure. The danger may rise toward Considerable with extended warming....

weather

Clear skies, moderate though gusty northerly winds, and temps rising to near freezing at 8500' today. High pressure builds throughout the region over the next few days. Storms passing by to the north of us will attempt to flatten the ridge, but we'll only see clouds and increased west to northwest winds through mid-week. Longer range models offer some hope for something next weekend.

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

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

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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.