Forecast for the Salt Lake Area Mountains

Brett Kobernik
Issued by Brett Kobernik for
Sunday, January 27, 2013

There is an increasing MODERATE danger for triggering a slab avalanche that breaks into preexisting weak snow. This danger will be on the rise with increased wind speeds and as the anticipated storm adds more weight. Avoid steep slopes and gullies in the lower elevations again today to avoid wet snow avalanches.

Low
Moderate
Considerable
High
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Weather and Snow

Temperatures remain fairly mild this morning hovering right around freezing in the 7000 to 8000 foot range and in the mid 20s along the ridges. Southwest ridgetop winds are fairly light but anemometers are just starting to hint at an increase in speed. There was just a dusting of snow that occurred late Saturday.

Recent Avalanches

Two small skier triggered wind slabs were reported from Saturday, one in White Pine and one in Red Pine. Some collapsing was noted in a few observations as well. The layering issue revolves around recent wind slabs that are overlaying facets that formed on the surface during the last period of high pressure.

Ad
Avalanche Problem #1
New Snow
Type
Location
Likelihood
Size
Description

Your biggest concern today is finding a pocket where the recent winds as well as today's anticipated winds have formed enough of a drift (slab) over the weak snow formed during the recent period of high pressure. Pay attention to any collapsing or "whoomping" you experience. This is the most obvious clue that you've found one of these scattered problem areas. Areas above around 8000 feet on west through north through east facing slopes are the most suspect.

More details on this layering: (not crucial reading)

It's hard to escape a near surface faceting event during periods of high pressure like we just experienced despite the mild temperatures in the mountains. Things would've been much worse though with colder temps during that period. The result is a layer of small grained facets that formed on the surface most pronounced but not limited to thin snowpack areas and lower elevations where temps were colder. The recent rapid warming changed the facets in the lower terrain to a saturated layer of wet snow which will become quite stable as things cool. The southerly winds helped to redistribute and strengthen the weak snow in the higher terrain HOWEVER it also has formed a slab over these facets in some areas. The weakest snow I've been finding is in the shady sheltered terrain but there is no slab there currently. I rate this as a run of the mill faceting event that's not alarming but enough to cause concern and will no doubt catch a few folks off guard. NOTE THAT ANY PERSISTENT BURIED WEAK LAYER DEMANDS RESPECT.

Theses pockets that you might trigger today aren't all that large but enough to pose a threat. If you decide to risk getting into terrain where these are present, keep your consequences low by not being above rocks, trees or terrain traps.

As for the future, today would be a good day to do some sleuthing to find areas where the recently formed facets are not as pronounced as well as finding areas where wind slabs are not overlaying them. That way you have some areas to go riding over the next few days and feel confident that the anticipated new layer of snow is not going to produce a slab avalanche. Spacial variation is the key here and folks with enough avalanche experience to understand that terminology should be the only one's attempting the type of mitigation technique I just described.

Looking further down the road, I'm hopeful that the small grained nature of these facets will play a role in them bonding as they get buried deeper in the snowpack. I'm not anticipating these grains to produce a widespread problem but I certainly expect to hear about a few human triggered avalanches over the next few days. Time will tell. Approach this situation with caution until we see how things are reacting.

Avalanche Problem #2
Wet Snow
Type
Location
Likelihood
Size
Description

With the continued warm temperatures at the lower elevations, a mention of the possibility of wet snow avalanches is in order for those who might be traveling in the low elevations. It is very important to avoid steep terrain traps such as gullies and chutes where wet snow avalanches may funnel in from above you.

Additional Information

Southwest winds will gradually increase a peak this afternoon. Temperatures will remain fairly mild for most of the day prior to the cold front that will pass through late this afternoon. We could see some snow showers during the day but most areas should get a good shot of snow during the frontal passage. The flow will shift more northwest afterward and areas favored oragraphically in that flow should see some more accumulations overnight. I'm expecting most areas to get about 6 inches with up to a foot in the most favored locations. 6/10ths to 1 inch of water weight is anticipated. We'll get a break during the day on Monday then the secondary portion of the system will move in Tuesday and Wednesday and provide times of snowfall with a bit more accumulations. Overall it's not a huge storm but perhaps just about right for some more good riding conditions.

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If you trigger an avalanche in the backcountry - especially if you are adjacent to a ski area – please call the following teams to alert them to the slide and whether anyone is missing or not. Rescue teams can be exposed to significant hazard when responding to avalanches, and do not want to do so when unneeded. Thanks.

Salt Lake and Park City – Alta Central (801-742-2033), Canyons Resort Dispatch (435-615-3322)

Ogden – Snowbasin Patrol Dispatch (801-620-1017)

Powder Mountain Ski Patrol Dispatch (801-745-3773 ex 123)

Provo – Sundance Patrol Dispatch (801-223-4150)

Dawn Patrol Forecast Hotline, updated by 05:30: 888-999-4019 option 8.

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This advisory is produced by the U.S. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist. Specific terrain and route finding decisions should always be based on skills learned in a field-based avalanche class