Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Saturday - December 21, 2013 - 6:49am
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Very dangerous avalanche conditions exist in the backcountry, and there is a Level 4 or HIGH danger on drifted upper elevation slopes. Natural and human triggered avalanches are likely in some areas. Dangerous wind slab and persistent slab avalanche conditions are widespread across the Logan Zone at upper and mid elevations due to very weak preexisting faceted snow. You could trigger avalanches remotely, from a distance or below. Avoid travel in avalanche terrain this weekend. Stay off of and out from under steep slopes and obvious or historic avalanche paths..




special avalanche bulletin

THIS SPECIAL AVALANCHE ADVISORY IS FOR THE MOUNTAINS OF NORTHERN UTAH TO INCLUDE THE WESTERN UINTAS. DANGEROUS HUMAN TRIGGERED AVALANCHES MAY BE TRIGGERED IN STEEP WEST TO NORTH TO EAST FACING TERRAIN ABOVE 8000` IN ELEVATION. EXPERT ROUTE-FINDING IS REQUIRED FOR SAFE TRAVEL IN THE MOUNTAINS. THIS SPECIAL AVALANCHE ADVISORY WILL CONTINUE THROUGH THE WEEKEND. THIS ADVISORY DOES NOT INCLUDE SKI AREAS OR HIGHWAYS WHERE AVALANCHE CONTROL IS NORMALLY DONE.
current conditions

The Tony Grove Snotel at 8400' reports 4" of new snow overnight, containing 0.4 of an inch of water equivalent. It's 15 degrees this morning, and there is 31 inches of total snow containing 59% of average water content for the date. The 9700' Logan Peak weather station reports 10 degrees and west winds, currently averaging in the mid-teens this morning. The station shows several hours overnight with 30 mph average southwest winds and a high probability of significant drifting. Widespread, very weak preexisting faceted snow plagues the shallow snow on most slopes in the region, and is especially bad on upper and mid elevation slopes facing the northern half of the compass.

Faceted snow is widespread, very weak and getting weaker. This photo was taken on 12-17-2013 in the White's Bedground Area off Red Pine Ridge.
recent activity

Ski resorts from the Ogden and Salt Lake Area Mountains report another very active avalanche control day yesterday, and there were several human triggered avalanches in the Wasatch and Uinta backcountry, including a couple close calls.

Here's a picture of one of many human triggered avalanches from yesterday in the Wasatch Range. (White Pine PC)
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

After a fairly calm day in the mountains yesterday, southwest winds picked up for several hours overnight. Drifting caused the development of wind slabs, in many cases on top of very week preexisting snow. Natural and triggered wind slab avalanches are likely today on steep slopes with fresh deposits of drifted snow. You'll find wind slabs composed of stiffer snow in exposed lee slope terrain, especially in and around terrain features like gullies, scoops, sub-ridges, rock outcroppings, and cliff bands. We recommend that you avoid travel in all steep drifted terrain this weekend.
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

Yesterday's heavy new snow piled up on preexisting very weak sugary or faceted snow, which is widespread in the region. Natural and dangerous human triggered avalanches failing in old weak faceted snow or in the basal layers of the existing snow pack are likely in drifted terrain and in areas that picked up a foot or more of new snow since Thursday. You could trigger persistent slab avalanches remotely or from a distance, and this could be an especially bad scene if you trigger one from below. Collapsing and/or shooting cracks are obvious red flags requiring you to reevaluate your route. Avoid and stay out from under steep slopes, slopes connected to steep slopes and obvious or historic avalanche paths this weekend.
weather

Snowfall will continue through much of the day in the mountains, with another 2 to 4 inches forecast by evening. High temperatures at 8500' should reach around 22 degrees and moderate west winds are expected. Mountain temperatures will drop to around 15 degrees tonight with northwest winds and 1 to 2 inches of accumulation possible. It'll be mostly cloudy tomorrow with another 2 to 4 inches of snow forecast and moderate west winds. Unsettled weather will continue into the first part of next week, and a high pressure system will move in around Christmas Day.

Check out our one stop weather page........HERE
general announcements

The Utah Avalanche Center wishes you a safe and powder-filled holiday season. Please consider the UAC in your holiday giving plans - your donations pay for these advisories and we can't do this without your help.  What is it worth to you every day to get an avalanche and mountain weather advisory?  The cost of a beverage or the gas it takes to get up the canyon?  You can donate here.

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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 snow and avalanche conditions. You can also call us at 801-524-5304 or 800-662-4140, email by clicking HERE, or include #utavy in your tweet or Instagram.

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I'll issue these advisories on Monday, Wednesday, Friday, and Saturday mornings. 

This advisory is produced by the U.S.D.A. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist.