Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - February 17, 2018 - 6:44am
bottom line

Heightened avalanche conditions exist on many drifted slopes, and there are areas with CONSIDERABLE danger at upper elevations, where human triggered wind slab avalanches, 1 to 2' foot-deep, are likely. You will find great powder riding, mostly stable snow, and Low danger in sheltered terrain and at lower elevations.

  • Evaluate snow and terrain carefully, and make conservative decisions.
  • Avoid cornices and steep drifted terrain at upper elevations.




current conditions

We've found stellar powder riding conditions in the Central Bear River Range, with well over a foot of nice new snow at upper elevations, and a few much needed inches at lower elevations refreshing backcountry access routes. Unfortunately, westerly winds picked up yesterday, continued to blow overnight, and are forecast to increase further today ahead of a strong winter storm. While you will find mostly stable snow and a Low danger in sheltered terrain and at lower elevations, heightened wind slab avalanche conditions exist on many drifted slopes, and there are areas with Considerable danger at upper elevations.

  • The Tony Grove Snotel at 8400' reports 3" of new snow and 0.3" SWE (or Snow Water Equivalent) in the past 24 hrs. It's 20°F, and there's 63 inches of total snow, with 83% of normal SWE.
  • I'm reading 23°F at the UDOT Hwy 89 Logan Summit sheds, and after blowing 30 mph with gusts of 50 mph overnight, there's a 15 to 20 mph west wind.

recent activity
  • There were several natural avalanches that occurred during periods of heavy snow and strong wind Thursday and more yesterday. These soft wind slab avalanches, 1' deep and about 50' wide, were on drifted north through east facing slopes at upper elevations, and most were likely triggered by cornice falls.
  • Snowboarders unintentionally triggered, but escaped a couple slow moving soft slab avalanches in Miller Bowl above Tony Grove Lake Thursday. The 10" deep avalanches on a very steep NNE facing slope at around 8700' failed within the new snow and ran on a widespread slick rain-crust.
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

Continuing and increasing west wind will have plenty of soft snow to drift, will build up existing slabs, and create new drifts in lee slope deposition areas. Today's wind slabs will be stiffer, thicker, wider, run farther, and be less manageable than they were yesterday.

  • Wind slabs are made up of stiffer, drifted snow. They can appear chalky and rounded and can make hollow drum-like sounds.
  • Avoid drifted snow in and around terrain features like sub-ridges, cliff bands, scoops, and gullies.
  • Avoid ridge-top cornices, which often break further back than expected. Wind slab avalanches are likely today under cornices.
  • In some areas, wind slabs formed on slopes with poor snow structure, and dangerous avalanches failing on persistent weak layers are possible.
  • Cracking and collapsing or whumpfing are red flags indicating unstable snow.
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
  • Soft storm slab and loose avalanches entraining the recent new snow and running on a slick ice-crust are possible in steep terrain at upper and mid-elevations. Be aware of possible terrain traps, like trees, cliffs, or benches below you.
  • Continue to practice safe travel protocols by exposing only one person at a time when moving through avalanche terrain. Widespread buried faceted layers appear dormant for now, but if you trigger an avalanche running on old snow it could be dangerous. Continue to avoid very steep rocky slopes with shallow snow and poor snow structure.
weather

The National Weather Service in Salt Lake City has issued a Winter Storm Watch. A mild day is expected across the area today. A significant winter storm will move slowly through the region Sunday through Tuesday.

  • Today: A 20 percent chance of snow. Partly sunny, with a high near 32. Wind chill values as low as -6. Windy, with a west southwest wind 31 to 38 mph, with gusts as high as 55 mph.
  • Tonight: Snow, mainly after 11pm. Low around 27. Windy, with a west southwest wind 40 to 45 mph increasing to 50 to 55 mph in the evening. Winds could gust as high as 80 mph. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.
  • Sunday: Snow. Temperature falling to around 22 by 3pm. Windy, with a west wind 33 to 40 mph, with gusts as high as 55 mph. Chance of precipitation is 100%. New snow accumulation of 9 to 13 inches possible.
general announcements

Episode 5 of the UAC podcast To Hell in a Heartbeat - A Conversation With Tom Diegel and Matt Clevenger About the 12.26.08 Full Burial on Little Water is live. This podcast talks with Matt and Tom about their experience and the massive success of the To Hell in a Heartbeat video which has been viewed almost 3M times. Check it out on ITunes, Stitcher, the UAC blog, or wherever you get your podcasts.

We have discount lift tickets for Alta, Snowbird, Brighton, Solitude, Snowbasin,and Beaver Mountain. Details and order information here. All proceeds from your purchase go towards paying for avalanche forecasting and education.

The UAC Marketplace is online. The holiday auction is closed, but our online marketplace still has deals on skis, packs, airbag packs, beacons, snowshoes, soft goods and much more.

The UAC has new support programs with Outdoor Research and Darn Tough. Support the UAC through your daily shopping. When you shop at Smith's, or online at Outdoor Research, REI, Backcountry.com, Darn Tough, Patagonia, NRS, Amazon, eBay a portion of your purchase will be donated to the FUAC. See our Donate Page for more details on how you can support the UAC when you shop.

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 Check it out on ITunes, Stitcher, the UAC blog, or wherever you get your podcasts.

Now is a great time to practice companion rescue techniques with your backcountry partners. Here's our rescue practice video.

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

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.