Salt Lake Avalanche Advisory

Forecaster: Drew Hardesty

SPECIAL ANNOUNCEMENT

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This will be our last week of morning forecasts. After Easter Sunday, we will do intermittent afternoon updates until near the end of April or conditions become very benign, whichever comes first.

BOTTOM LINE

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


Danger Rose Tutorial

A mostly LOW danger will rise toward MODERATE with daytime warming and sun on the steep east to south to westerly facing aspects. Human triggered longer running wet sluffs will be possible as the wet snow quickly gains speed on the slick underlying crusts. Slide-for-life conditions exist in the steepest exposed alpine terrain.

Continued poor structure dictates a continued mention of the Low Probability-High Consequence deep/wet slab releases in thin rocky terrain, particularly the easterly aspects (northeast>southeast). By definition you'd call it Moderate...but it doesn't seem enough.

CURRENT CONDITIONS

A Pacific storm off to the west will drive our weather for the next couple of days. We'll have warm and windy conditions with a weak cold front passing through early evening with a stronger, colder front tomorrow evening. Mountain temperatures are inverted, with ridgetop temps in the mid 30s. Trailheads are in the mid to upper 20s. Winds are southwesterly at 10-15mph, but should catch fire as the day wears on. Mostly cloudy skies should 'burn off' (most real meteorologists would cringe at that description) and we'll have partly cloudy skies before long. Riding conditions are fair to middlin' when the superficial crusts soften...and best on low angle slopes devoid of old chicken heads, pinwheels, and debris. Have at it.

RECENT ACTIVITY

Received exactly zero observations from yesterday. Two older reports came in that should give us something to discuss -

A wet slab naturalled south of Snowbasin on a steep east-northeast facing slope at 9000'. Dimensions are an estimated 2-3' deep and 100' wide and thought to have peeled out on Monday. I plan to head that way this morning.

Details are a bit thin, but a person skinning in the Canyons backcountry on Monday likely remotely triggered a 'repeater' in what they call Home Run - a steep east facing slope at 9000'. Dimensions reported were 70' wide, running 300' vertical.

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

Two types of wet issues to deal with. I'll start with the most benign. Wet sluffs from the April Fool's few inches will be easy to initiate in the steepest terrain with sun and daytime warming. These should only pose an issue if caught too late in the day in unforgiving terrain. These will run on the stout 3" crust from the April 1 cold front.

THREAT #2
WHERE PROBABILITY SIZE TREND
      Over the next 10 hours.

OK - these wet avalanches are of a different character altogether...and could arguably be called deep or persistent slabs...(though for simplicity I'll call them wet b/c the snow is isothermal.) It's mostly a function of the weak interfaces within the snowpack - the crusts/facet interfaces...the depth hoar at the base of the snowpack. Add warm temperatures to make the snow damp, moist...or even wet - and we'll continue to have a conditionally unstable snowpack....with both natural and human triggered wet slabs possible.

Clues -

Collapsing. Presence of wet, damp,or moist depth hoar or very wet layers of snow - even beneath the wolf-in-sheep's clothing supportable crust. Other tracks on the slope mean nothing.

Wet slabs are a poorly understood - particularly in relation to timing. The above rose is my best guess estimate of where these are more likely to be found. Our problems may just fade away this spring...then again, I fear that we may have a wet slab problems until the snowpack is in the streams or aquifers....Stay tuned.

Glide avalanches remain possible in the steep east to northeast facing terrain of Broads, Stairs, and Mill B South of BCC.

(note - gray areas denote lack of snow)

MOUNTAIN WEATHER

We'll have mostly cloudy to partly cloudy skies, temps warming to near 50 at 8000' and 40 at 10,000'. Winds will blow 20-25mph from the southwest with some gusts into the 50s along the highest ridgelines. A weak cold front drops temps a bit early evening, with a strong cold front tomorrow evening. Temps behind the second front will drop to the low teens on Friday. We may see 2-5" by then. High pressure builds back for the weekend, with another weak system potentially on tap for mid-week.

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 and Park City – 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.

Twitter Updates for your mobile phone http://utahavalanchecenter.org/twitter)

Daily observations are frequently posted by 10 pm each evening.

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

UDOT canyon closures UDOT at (801) 975-4838

Wasatch Powderbird Guides does daily updates about where they'll be operating on this blog http://powderbird.blogspot.com/.

Remember your information can save lives.If you see anything we should know about, please participate in the creation of our own community avalanche advisory by submitting avalanche and snow observations. You can also call us at 801-524-5304 or 800-662-4140, or email by clicking HERE

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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.