Provo Avalanche Advisory

Forecaster: Drew Hardesty

SPECIAL ANNOUNCEMENT

We've extended the Special Avalanche Advisory through the National Weather Service. 1-2' deep and 200' wide avalanches will still be likely on a variety of steep north through southeasterly terrain today. Avalanches may still be triggered from a distance. Those without significant avalanche experience should avoid being on or under slopes approaching 30 degrees. The danger is more pronounced in the Logan and Uinta mountains....

BOTTOM LINE

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


Danger Rose Tutorial

A CONSIDERABLE danger remains for any steep north through southeast facing slope at the mid and upper elevations. Avalanches may release on slopes as gentle as 30 degrees, and are still likely to be triggered at a distance - or above you should you be beneath a steeper slope. Yesterday's instabilities will persist through today. Caution is warranted.

CURRENT CONDITIONS

The nose of another round of moisture has filled the skies, signalling the approach of yet another round of snow. Temperatures are rising from their overnight lows at midnight and are in the upper teens to mid-20s. Winds remain mercifully light with only the 11,000' anemometers showing speeds in the 15-20mph range.

A few inches here, a few inches there......since last Thursday, it's all added up to about 15-20" everywhere except for Provo (apologies)...Riding conditions are superb, though the sun damaged the southerly and off aspects yesterday.

RECENT ACTIVITY

Despite the lack of snowfall, the stronger westerly winds produced a number of sensitive wind slabs falling on the same surface weaknesses...and we have had reports of human triggered slides in the upper and mid elevation terrain.

Too many to mention. At least 15 reported human triggered slides yesterday and at least 30 since the 11th. (Check under Current Conditions for the expanding list.) One natural was reported from the Park City ridgeline. Human triggered slides were, and will remain, the rule and not the exception. We saw widespread sensitive soft slabs triggered 6" to 2' deep, with some reported up to 3' deep. Most 100-200' wide. Patterns extended from north through southeast that had been wind drifted (many from the stronger winds on Saturday), each failing on surface hoar and weak surface faceted snow that grew like weeds last Monday through Wednesday. (It should be noted that some released on west with a touch of south...) Many of these soft slabs released remotely, that it, at a distance - a common characteristic of buried, intact surface hoar.

New snow? Check. Recent wind? Check. Shallowly buried persistent weak layer? Check. Rapid warming? Check. Lots of triggers in the backcountry yesterday? Check. The odds continue to be stacked....

One disturbing outlier - control work in upper Little Cottonwood pulled out a repeater hard slab to near the ground on a steep northeast facing slope with a rough elevation of 10,800'. It pulled out 250' away from the bullet's target.

Collapsing and shooting cracks offered immediate signs of instability to others not observing slides.

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

Here's the truth of the matter: It'll be less sensitive today than yesterday, but it'll want to lure you onto the slope. This is perhaps why it will be more dangerous today than yesterday. Buried, intact surface hoar and faceted snow does not heal quickly. Recall their properties: collapse failure and remote propagation - at least 2 slides yesterday ripped out above the skier with the slab trying to rip the skier off a tree. Exceedingly weak in what we call 'shear' - ability to pull way back onto lower angled slopes. The stiffening slab may allow these slides to propagate wider than before.

Cold clear windless nights with high humidity early last week fostered the growth of these surface weaknesses, and while we usually count on sun and wind to damage or degrade them, Wednesday night's light, low density snow buried them all but intact. Uncommon. We now have a Colorado base with a Montana/Canada top. Take another step back.

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

More like LOW with pockets of CONSIDERABLE. You're more likely to trigger a deeper slab in steep shallow rocky terrain, particularly in areas that avalanched during the December cycle.

MOUNTAIN WEATHER

Yet another round of snow on this moist northwest flow. Favored locations may pick up the heavier end of 4-8". Provo may pick up a trace to two. Winds will be 15-20mph but gustier along the higher peaks. Temps will be in the low 20s. We'll get a bit of a break tomorrow with another pattern of precipitation likely by Thursday. Yet another weather pattern kicks snow into the weekend.

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.

Discount Lift tickets: Ski Utah, Backcountry.com, Alta, Deer Valley, Park City, The Canyons, Wolf Mountain, Snowbasin, Beaver Mountain, Brighton, Sundance, and Solitude have donated a limited number of tickets for sale at discounted prices.

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.