Salt Lake Avalanche Advisory

Forecaster: Drew Hardesty

SPECIAL ANNOUNCEMENT

I am issuing a Special Avalanche Advisory for the northern mountains of Utah, to include the Logan area mountains, the Western Uintas and the Wasatch Plateau. 2-4' of snow coupled with strong winds since Saturday is enough to create unstable avalanche conditions in localized terrain. Those without proper avalanche training and experience should avoid steep mountain slopes for the next few days.

BOTTOM LINE

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


Danger Rose Tutorial

In the wake of the storm, the backcountry is littered with pockets of CONSIDERABLE danger. The new CONSIDERABLE definition indicates "Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential." True enough. The danger is most pronounced at the mid and upper elevation northerly through easterly facing aspects approaching 35 degrees and steeper.

CURRENT CONDITIONS

A blizzard indeed. Current wind chill at 11,000' is -46F. Really.

Ahead of the storm, the southerly winds blew 45-55mph with gusts into the 80s, with even some off-ridgeline anemometers in Ogden cranking 40 gusting to near 80. 5-7" of 6% density is being reported overnight, adding to the couple-few inches during the day yesterday. It's a far cry from the graupel-and-Sierra-cement 15-20% we've enjoyed up until now (mostly). Since Saturday, this pushes storm totals to roughly 40-50" in the upper Cottonwoods, 25-35" in the Park City and Ogden mountains, and about 25" or so above Provo.

Temperatures are now below zero at nearly all mountain stations. The northwesterly winds are 15-20mph and skies remain mostly cloudy, with some light snow falling in the mountains. Riding conditions should be quite good.

RECENT ACTIVITY

We had no reports of activity in the backcountry yesterday, but observers reported continued collapsing of the snowpack and propagation with snow-tests beneath the now-infamous November 14 rime crust. Control workers at the ski areas reported stiff, stubborn hard slabs with some failures at the base of the snowpack but with no fracturing and release.

THREAT #1
WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

The additional snow and wind continues to put the screws to the slow-to-heal interfaces within the snowpack. With such a patchwork of conditions due to the severe scouring and loading events, conditions will vary wildly from slope to slope. For example, I've found very unstable conditions near Guardsman Pass and much more stable conditions a mile away to the north and west. You'll need to put in the work to determine the local structure, strength and energy. If this doesn't mean anything to you, avoid slopes approaching 35 degrees and steeper.

Generally, the probability of triggering one of these 2-4' deep slabs has decreased, but the consequences of triggering one is severe. They're most localized to mid and upper elevation north through east facing slopes, but trigger points will be isolated to certain thinner parts of the hard slabs out there. No results from slope cuts or cornice drops should offer little indication of stability.


THREAT #2
WHERE PROBABILITY SIZE TREND
      Over the next 24 hours.

New shallow soft wind drifts now sit above yesterday's myriad stubborn hard slabs. It may be possible to intentionally trigger the new drift to seemingly 'clean out' the hazard, only to trigger the hard drift beneath it. Very different - the upper has good probability, low consequence, the lower has low probability, high consequence. Cornices remain large and dangerous. Give them a wide berth.

MOUNTAIN WEATHER

We'll have mostly cloudy skies today with an occasional flurry or two. Temps will remain cold with highs lucky to reach the upper single digits. Winds will be 20-25mph from the northwest. Temps will rebound Friday ahead of the next approaching storm due Saturday night into Sunday. The long range models suggest a continued progressive storm track for Utah. Stay tuned.

GENERAL ANNOUNCEMENTS

Please contact Alta Central (801-742-2033) if you trigger a large avalanche in the backcountry - especially if you are adjacent to a ski area - 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.

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Wasatch Powderbird Guides flight plan.

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

Daily observations are frequently posted by 10 pm each evening.

Free UAC iPhone app from Canyon Sports.

Subscribe to the daily avalanche advisory e-mail click HERE.

UDOT canyon closures UDOT at (801) 975-4838

We appreciate all your avalanche and snow observations. You can also call us at 801-524-5304 or 800-662-4140, or email to uac@utahavalanchecenter.org

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.

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.

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.