Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Thursday - January 25, 2018 - 7:07am
bottom line

Dangerous wind slab avalanche conditions exist on drifted upper elevation slopes in the backcountry. Drifting from continuing strong southwest winds today will cause the danger to increase and become more widespread. Scary persistent slab avalanches are possible on very steep shady slopes and in rocky areas with shallow snow.

  • Evaluate snow and terrain carefully, and make conservative decisions.
  • Avoid travel in drifted terrain and steep rocky areas with shallow snow cover.



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current conditions

The Tony Grove Snotel at 8400' reports an inch or two of new snow overnight. It's 33°F, and there's 53 inches of total snow at the site containing 89% of normal SWE (Snow Water Equivalent). It's 25°F at the CSI Logan Peak weather station, with 35 mph wind, but the wind direction sensor still appears iced. South winds increased overnight on Ogden Peak and are currently blowing around 60 mph, with a recent gust of 76 mph. Expect strong southwest winds to continue today and snowfall to increase this afternoon. Drifting snow will cause a rising avalanche danger in the backcountry today. Dangerous wind slab avalanche conditions already exist at upper elevations and will continue to develop and become more widespread in exposed terrain.

recent activity

A skier was caught, deployed an airbag, and was partially buried by an avalanche he triggered in the backcountry above Park City yesterday. Report

In the Logan Zone:

  • One party reported triggering small wind slabs and some natural activity in exposed terrain in the Franklin Basin Area yesterday.
  • Another party intentionally triggered a couple small wind slabs off the ridge in Hell's Kitchen on Tuesday.

Chunks of drifted snow in a small natural wind slab avalanche observed in the Franklin Basin Area yesterday.

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

Wind slab avalanches, made up of drifted snow are likely in exposed upper elevation terrain. Strong and continuing southwest winds and snow today will create fresh wind slabs, which are likely be sensitive to human triggering.

  • Watch for and avoid fresh drifts on steep lee slopes and in and around terrain features like sub-ridges, gullies, scoops, and rock outcrops.
  • A ride in even a small avalanche could be particularly dangerous in areas with shallow snow, due to the potential for being dragged through rocks.
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

Snowpit tests still show propagation and slab failure on buried weak layers made up of sugary, faceted December snow. Dangerous persistent slab avalanches remain possible on very steep slopes with shallow snow and poor snow structure. On Tuesday, I triggered collapsing and found suspect shallow and weak snow conditions in the trees on a northwest facing slope. Yesterday, we wallowed around in knee-deep loose facets in the Dog Leg Trees area in Providence Canyon.

  • Pay attention to possible signs of instability like cracking and whumpfing or collapsing, but remember these signs aren't always present when avalanches are triggered, so you you have to dig to find poor snow structure.
  • As rather heavy and perhaps inverted new snow stacks up on slopes with existing poor snow structure in the next couple days, the danger of large persistent slab avalanches will increase.

Paige took pictures of these well developed and chained facets, which are widespread in Providence Canyon (1/24/18).

weather

A storm system along the West Coast will weaken as it approaches. The associated cold front will sweep across the area today. High pressure will return for the upcoming weekend and early next week.

  • Today: Snow, mainly after 11am. High near 27. Windy, with a south southwest wind 34 to 41 mph, with gusts as high as 60 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 3 to 5 inches possible.
  • Tonight: Snow showers. Low around 14. Wind chill values as low as -3. Breezy, with a west southwest wind 16 to 26 mph, with gusts as high as 40 mph. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.
  • Friday: Snow showers likely, mainly after 11am. Cloudy, with a high near 22. Wind chill values as low as -1. Breezy, with a west southwest wind 16 to 21 mph increasing to 23 to 28 mph in the afternoon. Winds could gust as high as 41 mph. Chance of precipitation is 60%. New snow accumulation of 3 to 7 inches possible.
general announcements

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Episode 3 of the UAC podcast is live. We talk with UDOT Avalanche Program Supervisor Bill Nalli on how he and his teams keep the Greatest Snow on Earth from avalanching over the open roads and highways of the state. 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 these 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.

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 tweet or 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.