Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Thursday - December 24, 2015 - 7:19am
bottom line

HIGH (level 4): Very dangerous avalanche conditions exist, especially in drifted terrain at upper and mid elevations. Large and destructive triggered avalanches remain likely. Resist the temptation, and continue to avoid travel in backcountry avalanche terrain today. Stay off of and out from under slopes steeper than 30 degrees and obvious or historic avalanche paths.




avalanche warning

THE FOREST SERVICE UTAH AVALANCHE CENTER IN SALT LAKE CITY HAS EXTENDED THE BACKCOUNTRY AVALANCHE WARNING.

* TIMING...EXTENDED THROUGH 6 AM MST FRIDAY

* AFFECTED AREA...ALL THE MOUNTAINS OF NORTHERN AND CENTRAL UTAH AND SOUTHEASTERN IDAHO TO INCLUDE THE WASATCH RANGE, THE BEAR RIVER RANGE, THE WESTERN UINTAS AND THE MANTI-SKYLINE PLATEAU. OTHER MOUNTAIN RANGES WILL LIKELY BE AFFECTED AS WELL

* AVALANCHE DANGER...THE AVALANCHE DANGER FOR THE WARNING AREA IS HIGH

* IMPACTS...HEAVY SNOWFALL COMBINED WITH STRONG WINDS HAS CREATED WIDESPREAD AREAS OF UNSTABLE SNOW. HUMAN TRIGGERED AVALANCHES ARE LIKELY AND WILL OCCUR IN MANY AREAS. STAY OFF OF AND OUT FROM UNDER SLOPES STEEPER THAN 30 DEGREES.

BACKCOUNTRY TRAVELERS SHOULD CONSULT WWW.UTAHAVALANCHECENTER.ORG OR CALL 1-888-999-4019 FOR MORE DETAILED INFORMATION. THIS WARNING DOES NOT APPLY TO SKI AREAS WHERE AVALANCHE HAZARD REDUCTION MEASURES ARE PERFORMED.
current conditions

There is a HIGH danger and you should continue to avoid backcountry travel in avalanche terrain today. Heavy snowfall and extensive drifting from strong and sustained west winds overloaded a very weak preexisting base, and unstable, avalanche-prone snow exists over widespread areas.

Footage: Snow cloud from a large natural avalanche off Cascade Peak yesterday morning as seen from Utah Valley. (12-23-15)

The Tony Grove Snotel at 8400' reports around 12 inches of new snow in the last 24 hours, containing 1.2" of water. The station reports a gain of 5" of water since Sunday, 12/20/15! It's 12 degrees this morning and there's 70 inches of total snow, now containing 110% of average water content for the date. It's 5 degrees at the 9700' CSI Logan Peak weather station, which recorded fairly light west wind overnight. Yesterday, west northwest winds blew in the 30 mph range and gusted into the 50s at the UDOT hwy 89 Logan Summit weather station, but they've subsided significantly.

The snow in the backcountry on the mostly gentle backside of Beaver Mt. showed many obvious signs of instability including extensive audible collapsing or whumpfing and very long, sometimes remote triggered shooting cracks. (Pagnucco, 12-22-2015)


recent activity

Saturday (12-19-15): A very experienced local rider who was separated from his companion is lucky to be alive after triggering a good sized avalanche, being caught and carried through thick trees, and then being mostly buried and trapped in the debris.

Sunday (12-20-15): A skier reported remote triggering a large hard slab avalanche Sunday afternoon on a drifted north facing slope high on the south rim of Logan Canyon off the ridge deviding Logan Canyon from Dry Canyon..... Go to his Report

A sizable remote triggered avalanche from Sunday in the backcountry above Logan Canyon. (Syrstad, 12-20-15)

The snowplow triggered a couple persistent slab avalanches Tuesday at lower elevations on the Hwy 89 road cut in Beaver Canyon. These were close to two feet deep and released on weak basal layer facets, sliding to the ground. (12-21-15)

Poor visibility yesterday prevented us from seeing the probable natural activity in the backcountry, but extensive avalanche activity was reported from the Wasatch and Uinta Ranges, and we have a very similar weak snowpack and picked up as much or more snow locally.

***To view our updated list of backcountry observations and avalanche activity from around Utah, go to our observations page

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

Widespread very weak snow is now overloaded by a few feet of heavier drifted snow and deceptive powder and very dangerous avalanche conditions exist in many areas. Dangerous persistent slab avalanches remain likely today, especially in drifted terrain at upper and mid-elevations.

***You should give slopes steeper than about 30 degrees some time to strengthen after the huge load they receaved in the last couple days. It'll be wise to continue to avoid backcountry avalanche terrain, but if you must venture into the mountains and into the backcountry, pay close attention to signs of unstable snow like recent avalanches, whumpfing, and shooting cracks, and be willing to reevaluate your plans. In these conditions you could trigger avalanches remotely, from a distance or worse, from below!

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

Differentiated from persistent slabs only by depth and slab hardness, deeper hard slab avalanches, also failing on weak faceted snow in the basal layers of the snowpack, are also likely, mainly in drifted upper elevation terrain.

weather

We can expect cloudy conditions and a 40 % chance of snow again today, with 1 to 3 inches of accumulation possible by this evening. Temperatures at 8500' will stay in the mid to lower teens and 15 to 20 mph southwest winds will push wind chills well below zero. Another wave of stormy weather will bring a bit more snow to our area, although most of the energy will be to our south and east, with continuing moderate southwest wind tonight and 4 to 8 inches of accumulation possible by late Christmas Day. Looks like we can expect a cold snowy day tomorrow, with high temperatures around 12 degrees and moderate north winds. Clearing and sunshine is expected for the weekend, the snowpack will not stabilize as quickly as powder starved riders loose patience, and we'll probably see a perfect setup for avalanche accidents in the backcountry.

general announcements

Please submit snow and avalanche observations from your ventures in the backcountry HERE. You can call us at 801-524-5304 or email HERE, or include #utavy in your Instagram or Tweet us @UAClogan. To report avalanche activity in the Logan Area or to contact the local avalanche forecaster call me, Toby, at 435-757-7578. 

I'll update this advisory throughout the season on Monday, Wednesday, Friday, and Saturday mornings by about 7:30

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.