Lawinenlagebericht

Salt Lake

Veröffentlicht am Feb 20, 2021gültig bis Feb 21, 2021Utah Avalanche Center

Lawinengefahr

Hochgebirge
Waldgrenze
Unterhalb der Waldgrenze

Veraltet — dieser Lagebericht ist 6 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A CONSIDERABLE avalanche danger exists on many slopes at the mid and upper elevations. Considerable means that dangerous human triggered avalanches are likely.

The danger is more prevalent on west to north to southeast facing slopes and on any freshly wind drifted terrain.

Any avalanche you trigger may step down into deeply-buried weak layers, creating very large and destructive avalanches 6-8' deep and hundreds of feet wide.

All the experienced backcountry riders I know are setting wide margins of safety and continue to rule out steep terrain for now.

The Good News: Safe and enjoyable powder can be found on low angle slopes with no overhead hazard.

Lawinenprobleme

Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Hochgebirge
Waldgrenze
Unterhalb der Waldgrenze
Wahrscheinlichkeit
Likely
Größe
4
In the past week, we have added 3-7 feet of snow containing 3-7 inches of water to a very weak and faceted snowpack in the mountains above Salt Lake. Although it may be a little bit harder to trigger an avalanche failing in these deeply-buried weak layers, any avalanche you trigger will be very large and destructive - 4-8' deep and hundreds of feet wide. Or even larger.

The most suspect terrain continues to be the west through north through southeast facing aspects at mid and upper elevations. HOWEVER, with so much snowfall - upper elevation south-facing terrain and low elevation north-facing terrain may also produce avalanches that break on buried persistent weak layers. Avoid being on or underneath any slope steeper than 30 degrees where this persistent weak layer is present.

Keep in mind:

Avalanches can be triggered from a distance or below.

Avalanches are running downhill thousands of feet and crossing hiking trails and summer roads.

Any fresh wind slab, cornice fall, or new snow avalanche may step down several feet into older snow.

Signs of instability, such as cracking or collapsing, might not be present today.

I am especially wary of outlying areas that hold a weaker and thinner snowpack, including Millcreek, Lambs Canyon, Snake Creek, and much of the Park City ridgeline,
Wind Slabs
N
NE
E
SE
S
SW
W
NW
Hochgebirge
Waldgrenze
Unterhalb der Waldgrenze
Wahrscheinlichkeit
Likely
Größe
2
Winds have increased during the overnight hours and will persist into today. These winds will have plenty of fresh snow available for transport, and fresh wind drifts and likely at the mid - and especially upper - elevations. Although you are more likely to find fresh drifts on the leeward aspects facing north through southeast, terrain may channel and funnel winds, with wind drifts possible on any aspect. Watch for signs of sensitive wind drifted snow such as cracking. Any avalanche initially occurring in a fresh wind drift may step down into deeply-buried weak layers, creating a very large avalanche.

Also watch for fresh cornices along exposed ridgelines. These cornices may be sensitive, and any cornice falls may also step down to deeply-buried weak layers.

Special Announcement

On Monday, February 22, at 7 PM, the UAC will livestream a one hour review and debrief of the tragic Wilson Glades avalanche accident, followed by a Q & A period. The link for registration is HERE.

A good primer for this will be to listen in to yesterday's RadioWest conversation about avalanches and the incident. Stream it here or wherever you get your favorite podcasts.

Recent Activity

Wednesday and Thursday's Extreme avalanche danger literally shook the Wasatch Range. The aftermath looks like a war zone: plenty of trees snapped, new avalanche paths, some paths running farther than they have in years. I am glad we did not hear of any incidents or close calls. Next time you see an avalanche worker or plow driver in a red or orange coat, maybe give them a nod of thanks.

It is worth mentioning that we in particular and the West in general are not out of the woods yet: We've suffered 22 avalanche fatalities in 21 days in the West, the most recent in Idaho and Wyoming. Utah is up to 6 avalanche fatalities for the season.

Conditions remain dangerous in many areas.

Clear skies Thursday allowed control work to be performed by helicopter in some of the large slide paths in Big Cottonwood Canyon. Thanks to Powderbirds and UDOT for this footage of Stairs Gulch. It's about 2 minutes long, but worthy of your time!

Two days in a row of no new avalanches reported from the backcountry.

Snow and Weather

Another storm is on the doorstep. Good radar returns highlight the early morning snowfall in the Ogden mountains and the central Wasatch should start to see snowfall in the next hour or two. The more orographically favored terrain may see upwards of 4-8"+ by early evening. This will arrive on top of yesterday's couple inches and a variable early morning rime crust.

Current mountain temperatures are in the upper teens to low 20s. Winds have been from the south, blowing 35-40mph with a few 11,000' gusts into the 90s.

With the arrival of the cold front, temperatures will drop back down to the low teens enroute the single digits tonight. Northwest winds will remain gusty aloft, with hourly wind speeds averaging 20-30mph.

We get a bit of a break Sunday and Monday with the next disturbances moving through Tuesday and possibly again Thursday night. You'll get whiplash just watching the temperatures this week.

Our Week in Review - where we highlight significant avalanche and weather events - is available. It is worthwhile reading this summary of this very active past week.

Some approximate snow and water totals over the past 7 days:

Little Cottonwood: 5-7' (4-6.75" water)

Big Cottonwood: 2-5' (2-5" water)

PC Ridgeline: 2-3' (1-2.5" water)

Ogden area: 2-3' (1-2.5" water)

Provo area: 1-2.5' (1-2.5" water)

Additional Info

These are two examples of avalanches from the recent avalanche cycle: the first is off Tuscarora in the Brighton periphery. The second is near West Scotties in the lower White Pine drainage of LCC. The first is upper elevation, east facing and open terrain. The second is mid-elevation, west facing, and more interspersed with trees. Quite different from one another, but they are both avalanche terrain. Both could kill you. Slope angle is the great equalizer right now.

pc: Bill Nalli

pc: Mitch Potter

General Announcements

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This information does not apply to developed ski areas or highways where avalanche control is normally done. This forecast is from the U.S.D.A. Forest Service, which is solely responsible for its content. This forecast describes general avalanche conditions and local variations always occur.

Observations and Avalanches

Backcountry Emergency Procedures