Avalanche Advisory
Advisory: Salt Lake Area Mountains Issued by Drew Hardesty for Thursday - April 27, 2017 - 6:15am
bottom line

EXTRA CAUTION ADVISED: Human triggered wind and storm slabs are probable in steep wind drifted terrain this morning. They'll be most pronounced on steep north to east to south facing terrain of the mid and upper elevations. Note that conditions can turn on a dime in the springtime: with any periods of direct sun, the snow is likely to become damp and unstable, leading to the potential of natural wet avalanches.

Most ski resorts are closed for the season and they no longer perform avalanche mitigation, so treat them just like backcountry terrain.‚Äč Additionally, be sure to follow any restrictions the closed resorts may have for uphill travel. Alta ski area is currently closed to uphill traffic.




special announcement

Alta is closed to uphill traffic today.

We have stopped issuing regular avalanche advisories for the 2016/2017 season. For the rest of the month we will issue Friday updates for the central Wasatch Mountains and updates any time there is measurable snowfall; however, we have discontinued issuing avalanche danger ratings altogether.

current conditions

Overnight snow totals are up to 10" (.97" snow water equivalent) in upper Little Cottonwood, with about half that amount in Big Cottonwood and the Park City ridgeline. The Ogden area mountains picked up 5" and the Provo area mountains 2-4". The snowfall intensity was particularly high between 2 and 4am, leading to a natural avalanche cycle during those hours. Snowfall appears to be a bit more showery now with "face-stinging graupel" currently being reported in the Cottonwoods.

Winds ramped up out of the west northwest around 2am and are blowing 25-30mph with gusts to near 50. Even the Reynolds Peak weather station in mid-BCC has hourly averages of 20-25mph with gusts to 35. 11,000' winds are 45mph with gusts to 65. Temps are in the low 20s.


Snow depths are up to 150" in upper Little Cottonwood and 136" in upper Big Cottonwood (elevations 9600') . The Ogden mountains still boast 90"-105" (8000' elevation sites) and the Provo mountains have 100" at 8800' elevation. The Alta Guard broke 500" during Tuesday's storm for the 18th time since 1944 and the first time since 2010/2011. Alta Guard monthly snowfall can be found here.


For more information:

  • Weather stations and wind sites click HERE.
  • Weather forecast and discussion click HERE.
  • NOAA snow and avalanche page click HERE.
recent activity

Yesterday: Tuesday's widespread instability mostly stabilized yesterday with only one size 2 natural reported in the radical terrain of Tanners Gulch in mid-LCC. Narrow windows of "sun-breaks" (as the Pacific northwesterners call them) aided and abetted the warming and greenhousing to allow for some minor rollerballing and push-a-lanches as the Tuesday storm snow dampened to become unstable in localized terrain.

This morning: As mentioned above, the high precipitation intensity and strong west to northwest winds led to a natural avalanche cycle noted in the steep south facing mid-canyon paths of Little Cottonwood, with another noted this morning on Hellgate. All estimated to be size 2 (big enough to bury a person). Refer place names to Wasatch Backcountry Skiing map.


Full list of reported avalanches HERE

Other observations HERE.

Although we will be shutting down regular operations, we will continue to post recent avalanche activity and observations, so please do continue to send them to us. You can check the latest observations here. We also follow avalanche-related activity on Instagram - be sure to tag your photos with #utavy .

Avalanche Problem 1
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

The moderate to strong west to northwest winds will easily promote wind slab formation both to the lee of the high ridgelines but also cross-loaded beyond sub-ridges and other terrain features as they race up the westerly drainages of the central Wasatch mountains. Even the base of Alta has gusts into the 30s. Both wind slabs and storm snow slabs will be particularly sensitive to human provocation this morning on all steep terrain of the mid and upper elevations, most notably on steep north to east to south facing terrain. Overall stability should slowly improve as the day wears on.

Test slopes and snow tests should provide meaningful information to go along with the classic signs of instability in the form of cracking and collapsing of any recently drifted snow. Note that the drifts may be up to 18-20"+ in heavily loaded terrain while the storm slabs will be about half that.

In a nutshell: sensitive, widespread and up to 2' deep.

For more infomation on these and other avalanche problems in general, check in with the Avalanche Problem Toolbox.

Avalanche Problem 3
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Wet Snow Avalanches - These are always a possibility in the spring. With so much new snow, these avalanches will occur as soon as the sun appears. Even an hour of strong sunshine could start a cycle of wet snow avalanches.

Glide Avalanches - Although lower elevations and south aspects are beginning to melt out, there is still a deep, 10' snowpack in the upper elevations. The following aerial photo from April 5 shows glide cracks in Stairs Gulch. With a deep snowpack in the alpine regions, Spring mountaineering conditions are prime right now in the Wasatch. However, certain drainages in Big Cottonwood Canyon - including Stairs Gulch, Mill B South, and Broads Fork - are also known paths for glide avalanches, and this terrain should be avoided. (We received an excellent, personalized observation discussing glide avalanches, and you can also visit Bruce Tremper's blog on glide avalanches as well.)

weather

We'll see intermittent showers today with some possibility of additional "sun breaks". Temps will remain generally cool along the ridgelines with a cooling trend continuing through tomorrow. Ridgetop temps will be in the upper teens to low 20s. Winds should be at their highest hourly averages now, but expect the west to northwesterlies to blow 20-25mph throughout the day. We should see a few more inches tonight with additional "wrap-around" moisture with the departing Low pressure system tomorrow into Saturday. It may all add up to another 5-10" by then.

general announcements

Remember your information can save lives. If you see anything we should know about, please help us out by submitting snow and avalanche conditions. You can also call us at 801-524-5304, email by clicking HERE, or include #utavy in your tweet or Instagram.

To get help in an emergency (to request a rescue) in the Wasatch, call 911. Be prepared to give your GPS coordinates or the run name. Dispatchers have a copy of the Wasatch Backcountry Ski map.

Backcountry Emergencies. It outlines your step-by-step method in the event of a winter backcountry incident.

If you trigger an avalanche in the backcountry, but no one is hurt and you do not need assistance, please notify the nearest ski area dispatch to avoid a needless response by rescue teams. Thanks.

EMAIL ADVISORY If you would like to get the daily advisory by email you will need to subscribe here.

DAWN PATROL Hotline updated daily by 5-530am - 888-999-4019 option 8.

TWITTER Updates for your mobile phone - DETAILS

UDOT canyon closures: LINK TO UDOT, or on Twitter, follow @UDOTavy, @CanyonAlerts or @AltaCentral

Utah Avalanche Center mobile app - Get your advisory on your iPhone along with great navigation and rescue tools.

Powderbird Helicopter Skiing - Blog/itinerary for the day

Lost or Found something in the backcountry? - http://nolofo.com/

Ski Utah mobile snow updates

To those skinning uphill at resorts: it is critical to know the resort policy on uphill travel. You can see the uphill travel policy for each resort here.

Benefit the Utah Avalanche Center when you shop from Backcountry.com or REI: Click this link for Backcountry.com or this link to REI, shop, and they will donate a percent of your purchase price to the UAC. Both offer free shipping (with some conditions) so this costs you nothing!

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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