Avalanche Advisory
Advisory: Salt Lake Area Mountains Issued by Drew Hardesty for Saturday - January 13, 2018 - 5:32am
bottom line

We have a CONSIDERABLE avalanche danger on many slopes in the backcountry. The danger is real. Human triggered slides up to 3' deep are likely and may be triggered from below. The danger is most pronounced on steep northerly through easterly facing slopes at the mid and upper elevations.

If you're headed into the backcountry - or exiting though the gates at the ski area - you must have the proper gear, training, and skilled partners. Chance and hope are poor risk management strategies.

PSA - Be aware of other parties in the backcountry - you would never would want to accidentally trigger a slide onto a party below - by remotely triggering a slide or kicking a cornice.




special avalanche bulletin

THE FOREST SERVICE UTAH AVALANCHE CENTER IN SALT LAKE CITY HAS ISSUED A BACKCOUNTRY AVALANCHE SPECIAL BULLETIN.

* TIMING…IN EFFECT FROM 9 PM MST FRIDAY TO 9 PM MST MONDAY

* AFFECTED AREA…FOR THE MOUNTAINS OF NORTHERN UTAH INCLUDING THE WASATCH RANGE...BEAR RIVER RANGE...UINTA MOUNTAINS.

* AVALANCHE DANGER…DANGEROUS HUMAN TRIGGERED AVALANCHES REMAIN LIKELY.

* IMPACTS…BEAUTIFUL WEATHER OVER THE HOLIDAY WEEKEND AND RECENT FRESH POWDER SNOW WILL LEAD TO A SIGNIFICANT INCREASE IN PUBLIC USE IN THE MOUNTAINS OF NORTHERN UTAH. SNOWPACK, WEATHER, AND HUMAN CONDITIONS ARE PERFECTLY ALIGNED FOR A POTENTIAL ACCIDENT THIS WEEKEND. MANY SLOPES, ESPECIALLY ONES ABOVE 8000 FT WITH A NORTHERLY THROUGH EASTERLY ASPECT, ONLY NEED A SKIER OR RIDER TO TRIGGER AN AVALANCHE 2-3 FEET DEEP AND SEVERAL HUNDRED FEET WIDE.

THIS WARNING DOES NOT APPLY TO SKI AREAS WHERE AVALANCHE HAZARD REDUCTION MEASURES ARE PERFORMED.
current conditions

Clouds currently enveloping the Wasatch should burn off quickly this morning. West to northwest winds are blowing 10-15mph with gusts to 25. The highest elevation anemometers hum at 25mph with gusts to 30. Temps are in the upper teens to low 20s. Riding conditions remain quite good on the shady, sheltered slopes, but you'll find plenty of wind damage in the open, exposed bowls and in the high alpine terrain.

Snow depths are 40-50" at 9000' with many snow stakes sitting at 70% of normal.

"Week In Review" found HERE. These are published each Thursday night. Archived advisories can always be found here.

Progression of danger roses and overall hazard rating from 12/29 - 1/4. (Click on the day of the week for the archived forecast for that day.)

Friday Saturday Sunday Monday Tuesday Wednesday Thursday

Low Low Considerable Moderate Considerable HIGH HIGH
recent activity

While cracking and collapsing remained a common theme, there were no reports of avalanches from the backcountry yesterday. Explosive control work at the resorts, however, yielded large hard slab avalanches 2-5' deep, leaving impressive amounts of debris in the runout zones.

Spatial distribution of avalanches since January 7th. Photos of recent slides can be found here. Thursday remotely triggered slide in BCC below. (pc:Torrey)


List of all avalanches found 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

The fact that no backcountry avalanches were reported yesterday means nothing. We all have our individual levels of acceptable risk, but none of the forecasters here would consider jumping into steep terrain holding this current poor structure. If we were crossing beneath the steep terrain, we'd do so quickly and one at a time. In my view, the risk/reward curves are not parallel for the current conditions. Remember, however, that by choosing low angle slopes with no overhead hazard, you have low risk/high reward. You also have options with your aspects in a similar* regard.

Guide/avalanche educator John Mletschnig put it well in his observation from the top of Big and Little Cottonwood yesterday - "Overlaying slab is now a meter deep in many high elevation areas in upper BCC/LCC and consequently (more) difficult to trigger. More than one interface facet layer could act as a failure layer. From the surface the snowpack appears more stable than it should be trusted due to a capping effect of the slab and dense, smoothed out graupel surface. Thin spots in the slab and large triggers could easily bring down large well connected slabs potentially running long and far. Remotely triggering an avalanche remains a distinct possibility."

*As you can see in the accompanying rose, the potential for human triggered slides is much more likely on mid and upper elevation northerly to easterly facing slopes.

Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 12 hours
description

Slowly stabilizing soft and hard slabs litter the open bowls and exposed alpine terrain and may still be sensitive to provocation (you). With soft slabs, you're in the snow; with hard slabs you're on top of the snow. The second kind tends to break well above you when you collapse the tapering teardrop of slab. Triggered wind slabs may step down into older, weaker snow, producing a much larger avalanche.

weather

Any cloudy cover should start to burn off soon. We'll have winds out of the northwest, blowing 10-15mph. Ridgetop temps will rise toward the upper 20s. High pressure builds in over the next several days with a couple storms on the horizon - one for mid-week and another for the weekend. More info on our Mountain Weather page, updated by noon.

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.