Avalanche forecast

Ogden

Issued Dec 18, 2022valid to Dec 19, 2022Utah Avalanche Center

Avalanche danger

Alpine
Treeline
Below treeline

Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Areas of CONSIDERABLE avalanche danger exist on all northwest through east facing aspects at ALL ELEVATIONS (even LOW ELEVATIONS) for triggering avalanches 1-4' deep and hundreds of feet wide. These avalanches may be triggered at a distance, even from below. Areas of MODERATE avalanche danger exist on all other aspects and elevations. You can also trigger new soft slab avalanches of wind blown snow in the upper elevations today.

Avoid traveling on, below, or adjacent to slopes 30 degrees or steeper on northwest through north thorough the easterly aspects. Safe and excellent riding can be found on low angle slopes with nothing steeper above you.

Avalanche problems

Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alpine
Treeline
Below treeline
Likelihood
Likely
Size
3
There is weak, sugary faceted snow (a persistent weak layer, or PWL) on almost all aspects and elevations throughout the Wasatch Range. This PWL has been buried by several feet of storm snow and wind-drifted snow which has created dangerous avalanche conditions, with three serious avalanche accidents this past week. WHAT IS UNUSUAL is that each of these avalanche accidents took place in the lower elevations bands below 8000’. What this means is that these avalanches can occur not far from parking lots or trailheads.This PWL is especially dangerous on aspects facing northwest through north and east where triggering avalanches is likely.

Although avalanches involving this PWL are less likely on solar aspects facing west through south, there is too much uncertainty given the amount of snow we have received this past week and avalanches failing in this PWL are still possible.

Examples of this problem (triggered near the Cutler Ridge Thursday (Keeler) and during the storm (mid-week).

Ben Lomond 8200', NE aspect during the storm. PC unknown

TREND: Slowly decreasing in sensitivity and spatial extent. Size remains the same.
Wind Slabs
N
NE
E
SE
S
SW
W
NW
Alpine
Treeline
Below treeline
Likelihood
Possible
Size
2
Southwesterly winds overnight have had plenty of low-density snow to blow around and you are likely to find sensitive slabs of wind-drifted snow at the upper elevations. The new soft slabs will be most pronounced on north through east through south facing slopes.

Any wind slab avalanche that you trigger has the potential to step down into deeper weak layers in the snowpack, creating a very large and dangerous avalanche.

Look for evidence of fresh drifts and wind slabs that look wavy, rounded, smooth, and pillowy, and avoid those slopes. Signs of sensitive wind-drifted snow include cracking and collapsing of the more dense drift over lower density snow below.

Long running dry sluffs are still possible in the cold, dry snow...and may transition to wet loose sluffs with today's direct sun and warming temperatures.

TREND: Decreasing danger

Special Avalanche Bulletin

DANGEROUS AND UNUSUAL AVALANCHE CONDITIONS WILL LAST THROUGH AT LEAST THIS WEEKEND. HEAVY SNOWFALL THIS PAST WEEK HAS CREATED DANGEROUS AVALANCHE CONDITIONS AT ALL ELEVATIONS. DON'T BE LURED BY THE BEAUTIFUL SUNNY SKIES AND FRESH POWDER INTO THINKING AVALANCHE CONDITIONS ARE SAFE WHEN THEY ARE NOT.

DO NOT TRAVEL ON, UNDERNEATH, OR ADJACENT TO SLOPES 30 DEGREES OR STEEPER ON SLOPES FACING NORTHWEST, NORTH, NORTHEAST, AND EAST WHERE TRIGGERING LARGE AND DANGEROUS AVALANCHES IS LIKELY. THIS INCLUDES LOW-ELEVATION FOOTHILLS WHERE AVALANCHES CAN OCCUR NOT FAR FROM PARKING AREAS AND TRAILHEADS.

Recent Activity

I published a blog "Dangerous and Unusual Avalanche Conditions" describing the avalanche accidents in the central and southern Wasatch over this past week.

THERE WERE THREE SIGNIFICANT AVALANCHE ACCIDENTS THIS WEEK with serious injuries. Two injured parties required rescues. The avalanches broke down over 2' deep into the layer of November facets. These avalanches occurred at low elevations below 8,000':

Tuesday - Pink Pine Ridge 7,800' North-facing 2-3' deep, 60' wide. Read the preliminary report. UAC staff visited the area on Wednesday, but due to avalanche danger, chose not to approach the avalanche.

Wednesday- Thomas Fork in Neffs Canyon 7,200' North-facing 2' deep 200' wide. Read the preliminary report.

Friday, December 9, an avalanche accident on Santaquin Peak in the Provo mountains that failed in the persistent weak layer of faceted snow also involved serious injuries. The avalanche was 1-2' deep and 600' wide.

(rescue from Pink Pine, pc: Wasatch Backcountry Rescue)

An experienced party traveling near Monte Cristo reported some cracking in the snowpack yesterday. There report is HERE>

On Friday, near Grandview Peak, a snowmobiler remotely triggered (triggered at a distance) a soft slab failing on our PWL (persistent weak layer) of weak faceted grains. The avalanche was on a steep northeast facing aspect at 9200' with estimated dimensions of 2' deep and 300' wide. (photo below). Mark Staples rode up to investigate and his report yesterday is HERE>

Check out all the avalanches HERE and if you see an avalanche, please report it.

Snow and Weather

Skies are clear. Mountain temperatures are in the upper teens and low 20s. Winds are westerly, blowing 15-20mph with gusts to 20mph. The highest anemometers are recording hourly averages of 25-30mph with gusts to 35.

Riding conditions are excellent although solar aspects will have a thin crust this morning before it thaws. Nit-pickers will complain of a bit of wind damage up high.

For today, we'll have sunny skies with light to moderate westerly winds. Temperatures will warm to the mid-20s. For the outlook, we'll be under a zonal (westerly) then cool northwest flow with embedded disturbances through the week. We may pick up a few inches with a mid-week storm.

Get caught up in significant weather and avalanche activity over this past week by reading our Week in Review.

Additional Info

Mark Staples has also written a season summary HERE.

General Announcements

CLICK HERE FOR MORE GENERAL INFO AND FAQ

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

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