Avalanche Advisory
Advisory: Salt Lake Area Mountains Issued by Greg Gagne for Friday - April 28, 2017 - 6:16am
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Human triggered wind and storm slab avalanches are possible today. Any increase in wind and or snowfall can quickly elevate the hazard. Conditions can change almost instantly during the Springtime, with sensitive wind or storm slabs one minute, followed by the potential of natural wet avalanches if the sun appears even for a short time. Pay attention to rapidly changing conditions.

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

As of 6 am: Overnight snow totals are 2-4" in the Cottonwoods, with Little Cottonwood on the higher end. West/northwest winds which have been sustained for the past 24 hours, gusting in the 30's - 50's mph, have diminished since 3 am, and are now gusting into the teens and low 20's mph out of the west/northwest.

Temperatures are more appropriate for late January than late April, with mountain locations ranging through the teens.

Approximate storm totals this past week are 18-40" with over 4" of water, with Little Cottonwood Canyon on the higher end of snow and water totals.


Week in Review

Perhaps Ullr is thanking us for our perseverance the past several seasons as the last week of April delivered Winter 2.0:

Friday April 21 featured 8" of snow in the Cottonwoods with minor sluffing and small, wet-loose activity reported.

Saturday brought an extended period of east winds and cool temperatures with several skier-triggered slides from fresh wind drifts in the upper elevations.

Sunday included wet loose activity as the sun warmed the snow surface.

Snowfall began on Monday and continued well into Tuesday. Storm totals at Alta totaled 26" with 2.6" of water. Snowfall rates of 3-4" per hour were observed in upper Little Cottonwood Canyon, generating an early-morning natural cycle with several natural as well as skier-triggered avalanches running at the new snow/old snow interface.

As is often the case in the Spring, by Wednesday conditions rapidly settled out with only minor wet loose activity reported.

Snowfall began overnight Wednesday into Thursday, with 10" of snow in LCC, and about half that amount in BCC and the Park City ridgeline. This storm featured strong northwest winds that created sensitive wind slabs in the mid and upper elevations, with

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

Widespread skier-triggered activity was reported from Little Cottonwood Canyon on Thursday. These slides involved fresh wind drifts at the mid and upper elevations, breaking out 8-12" deep, failing at either a layer of graupel or a lower-density layer within the storm snow. Most of these were smaller pockets, but a large wind slab avalanche was unintentionally triggered midday on southeast facing Cardiff Bowl, propagating 1000-1500'. Although other reported slides were smaller, at least one report involved a slide that took out a skin track with a skier being carried s short distance.

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

Sustained west/northwest winds created very-sensitive, widespread wind slabs at the mid and upper elevations on Thursday. Although these are likey to be less sensitive today, additional storm snow and winds may create a fresh batch today. Watch for signs of instability such as cracking and collapsing of any recently drifted snow. A common theme of avalanche activity this past week was a general surprise at how widely avalanches were propagating.

Winds are forecasted to shift to the northeast overnight and into Saturday, creating additional fresh wind drifts.

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

Avalanche Problem 2
type aspect/elevation characteristics
LIKELIHOOD
LIKELY
UNLIKELY
SIZE
LARGE
SMALL
TREND
INCREASING DANGER
SAME
DECREASING DANGER
over the next 24 hours
description

Additional snowfall during the day on Friday may create sensitive storm slabs, especially if there is a spike in precipitation intensity (PI). Density changes within the storm snow can provide the necessary weak layer. Additionally, Friday may feature convective activity as the sun warms the atmosphere, and convective showers can quickly elevate PI rates for a short period.

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 natural 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

At least one more day of winter! Mountain temperatures today will rise into the 20's F and winds will be out of the north/northwest. Winds may gust into the 20's and 30's mph at the mid elevations, with stronger gusts at 11,000' Expected snowfall during the day today is 4-8". Winds begin to turn northerly later today which should begin to shut off snowfall overnight.

Snow showers may continue overnight and into early Saturday morning, with winds veering to the northeast. Temperatures will remain cool, but with increasing sun Saturday afternoon.

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!

Benefit the Utah Avalanche Center when you buy or sell on ebay - set the Utah Avalanche Center as a favorite non-profit in your ebay account here and click on ebay gives when you buy or sell. You can choose to have your seller fees donated to the UAC, which doesn't cost you a penny.

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