Boletín de aludes

Salt Lake

Publicado el Feb 20, 2024válido hasta el Feb 21, 2024Utah Avalanche Center

Peligro de aludes

Alta montaña
Límite del bosque
Bajo el límite del bosque

Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche danger is CONSIDERABLE at upper elevations where you are likely to trigger a wind-drifted snow avalanche near ridgetops and on the leeward side of terrain features. These wind-drifts may be covered over by new snow, will be hard to see, and could break above you. Mid and low elevation slopes have a MODERATE avalanche danger. There is a thin layer of facets associated with a crust now buried 1'-2' deep. We have been seeing avalanches triggered on this layer primarily on east-southeast and west facing aspects.

Careful snowpack evaluation, cautious route-finding, and conservative decision-making will be essential today and if in doubt travel on terrain less than 30 ° in steepness.

Problemas de aludes

Wind Slabs
N
NE
E
SE
S
SW
W
NW
Alta montaña
Límite del bosque
Bajo el límite del bosque
Probabilidad
Likely
Tamaño
3
Expect to see wind-drifts that could be 6"-24" deep and up to 150' wide. You may not see signs of wind-drifted snow, such as pillow-shaped deposits as they will be buried under the newest snow. There was a large natural wind-drifted snow avalanche reported from Ben Lomond and I would expect that we could see similar avalanches in high alpine terrain or along the Park City Ridgeline. Cornices are a sign of wind-loading and may be sensitive today breaking further back than you expect.

Video of active wind-loading on the Park City Ridgeline (Malone)
Persistent Slabs
N
NE
E
SE
S
SW
W
NW
Alta montaña
Límite del bosque
Bajo el límite del bosque
Probabilidad
Likely
Tamaño
3
A weak interface made up of a crust with small facets above it has been found on east-southeast and west aspects and maybe found on southerly aspects at mid and upper elevations. This crust is now buried 1'-2' deep. The stubborn and unpredictable nature of this layer means you may trigger an avalanche on this layer remotely. This avalanche problem is spotty-meaning that a snowpit in one location may not tell you if the slope you want to travel on has this buried layer. Assess each slope individually before committing to steep terrain on these aspects. Cracking and collapsing are signs that this layer is present. The tricky part is that this layer is buried on slopes we normally consider "safer". The early season persistent weak layer (PWL) avalanche problem is moving in the right direction as more snow is added to the snowpack, and the weak layer near the ground continues to gain strength. Triggering an avalanche on this layer may occur in an isolated area where it is thin, rocky and steep and likely places that avalanched earlier this month (repeater avalanches). February 15th and 16th were the last two reported avalanches failing on this layer. They occurred on northwest facing slopes at 10,500' that most likely loaded from the southerly wind event. If an avalanche were to be triggered in the PWL, it would be 4'-6' deep and well over a 100' wide primarily on northwest-north-northeast aspects at high elevations.
Loose Wet
N
NE
E
SE
S
SW
W
NW
Alta montaña
Límite del bosque
Bajo el límite del bosque
Probabilidad
Possible
Tamaño
2
Warm temperatures and a rain line to 7500' means we may see wet loose avalanches today. Roller balls, pinwheels, and sinking down into the surface snow are signs of instability. If the snow is saturated move to cooler snow at a higher elevation.

Special Announcement

Join the UAC and Inspired Summit Adventures for the grand opening of our new Transceiver Training Park at Pinebrook, Sunday, February 25, from 3:00-6:00PM.

Recent Activity

Yesterday we had reports of wind-drifted snow avalanches on Superior and Pioneer Ridge. We had one report of a cornice triggered avalanche in West Porter on an easterly aspect at 9,000' that failed on small facets above a crust. There was a wet snow avalanche from Sunday that resulted in a close call for an ascending group in Little Cottonwood Canyon.

Above photo from West Porter (DB)

Snow and Weather

This morning, under overcast skies trailhead temperatures are in the high 20's° F and the highest ridgelines are in the low 20's °F. Winds are blowing from the southwest 15 gusting to 25 MPH at the lower ridgelines and from a westerly direction 25 gusting to 55 MPH at the 11,000' ridgelines. Overnight we received 5"-8" of snow with .5"-1.36" of water weight. Today, look for overcast skies, mild temperatures 35°-39° F and winds blowing from the south-southwest 20 gusting to 30 MPH at the 9,000' ridgelines and 35 gusting to 55 MPH at the 11,000' ridgelines with isolated gusts to 70 MPH. We can expect to see intermittent snow showers through the day with 5"-6" of new snow and .35"-.55" of water by late afternoon. This may fall as rain below 7500'. There is a chance of lightning and periods of increased precipitation where we might go over on our snow and water numbers in some locations.

Our partners at the National Weather Service have issued a Winter Weather Advisory through 10pm Wednesday night.

Additional Info

Mark describes how to identify thin facets above a crust on aspects where we don't normally see avalanches. The Wasatch has more snow (thicker slab) over this weak layer.

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