Salt Lake Avalanche Advisory

Forecaster: Brett Kobernik

SPECIAL ANNOUNCEMENT

Bruce Tremper will be giving a free Science of Avalanches talk at the Treasure Mountain Middle School in Park City tonight at 6:30pm.

There are a number of slots open for our Advanced Avalanche Workshop later this month. Brett Kobernik will lead this class which will focus on our remarkable weak layer formation this year and persistent weakness in general. DETAILS


BOTTOM LINE

Danger by aspect and elevation on slopes approaching 35° or steeper.
(click HERE for tomorrow's danger rating)


Danger Rose Tutorial

There are pockets of a CONSIDERABLE avalanche danger. The most likely areas to find an avalanche are in the mid to upper elevation northwest through east aspects that have old weak snow with a recent slab on top. It is hard to judge which slopes have a slab present until you’re already on them so, unless you’re absolutely sure, it’s best to avoid the steep terrain. It is very difficult for me to trust steep slopes when a persistent weakness is present.


CURRENT CONDITIONS

Under clear skies, temperatures cooled to around 30 or even into the mid 20s at many locations. West winds increased and are in the moderate speed category. The snow surface remains variable and is described well in these two observations from Nalli and Hutchinson.


RECENT ACTIVITY

Ev was able to intentionally trigger a couple of small avalanches on northeast facing Clayton's Peak on Thursday. DETAILS.


THREAT #1

WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

“Persistent” is an adjective that we use to describe a type of weak layer in regards to a slab. There are a slew of definitions for the word "persistent":

1) lasting or enduring tenaciously.

2) existing for a long or longer than usual time.

and my favorite... 3) characterized by a specified habitual behavior pattern, especially a dishonest or undesirable one.

A persistent weakness is comprised of either faceted grains and or surface hoar. They are the bane of the backcountry enthusiasts existence. They are responsible for the majority of bad avalanche accidents and fatalities here in Utah. They can heal to the point where they're not dangerous any more ONLY after a significant amount of snow followed by enough time for settlement and bonding to occur. Our persistent weakness hasn't even reached it's apex of danger yet, let alone start to heal. In some places there isn't even a slab present, just all weak snow which is getting weaker. In others the recent skiff of snow and stronger winds have formed a slab that's scattered about and is sensitive to people screwing with it. With a persistent weakness, you’re patience needs to be persistent as well. These persistent slabs will collapse and fail long after you thought they should be stable. Only if you are 100% certain that there is not a slab over facets should you get onto steep slopes.


MOUNTAIN WEATHER

We'll see partly cloudy skies with temperatures not as warm as yesterday but still into the mid to upper 30s at 8000 feet. Moderate speed west winds should slow as the day goes on. A mild storm will move through on Saturday with snow showers that might add up a few inches of snow accumulation then high pressure starts to build back in. There is a slight chance this little system could produce a bit more snow than expected.


GENERAL ANNOUNCEMENTS

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 – Alta Central (801-742-2033)

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

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

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

Daily observations are frequentlypostedby 10 pm each evening.

Subscribe to the daily avalanche advisory e-mail clickHERE.

UDOT canyon closuresUDOTat (801) 975-4838

Wasatch Powderbird Guides are suspending the opening of helicopter skiing operations. Once we have enough snow cover, daily updates to this bloghttp://powderbird.blogspot.com/will begin for the 2011-2012 season.

You have the opportunity to participate in the creation of our own community avalanche advisory by submittingavalanche and snow observations. You can also call us at 801-524-5304 or 800-662-4140, or email by clickingHERE

Donate to your favorite non-profit –The Friends of the Utah Avalanche Center. The UAC depends on contributions from users like you to support our work.

We will update this forecast tomorrow morning. Thanks for calling..


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.


This advisory provided by the USDA Forest Service, in partnership with:

The Friends of the Utah Avalanche Center, Utah Division of State Parks and Recreation, Utah Division of Emergency Management, Salt Lake County, Salt Lake Unified Fire Authority and the friends of the La Sal Avalanche Center. See our Sponsors Page for a complete list.