Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Tuesday - December 22, 2015 - 7:21am
bottom line

HIGH (level 4): Avoid all backcountry travel in avalanche terrain today. Stay off of and out from under slopes steeper than 30 degrees and avoid all obvious or historic avalanche paths. Very dangerous avalanche conditions exist at upper and mid elevations. Large and destructive natural and human triggered avalanches are likely, and the continuing storm will only cause the danger to rise and become more widespread.




avalanche warning

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

* TIMING...IN EFFECT FROM 3:30 PM MST MONDAY TO 6 AM MST WEDNESDAY

* 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 IS CREATING WIDESPREAD AREAS OF UNSTABLE SNOW.  BOTH HUMAN TRIGGERED AND NATURAL 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

We strongly recommend that people should avoid backcountry travel in avalanche terrain today. Heavy snowfall and extensive drifting from strong and sustained southwest winds overloaded a very weak preexisting base, and unstable, avalanche-prone snow exists over widespread areas. There is a HIGH danger in the backcountry this morning, but the danger will continue to rise and become more widespread as the storm continues today and tonight, and it looks as though snowfall rates and winds may even intensify a bit tomorrow. Very weak faceted snow is widespread in the basal layers of the snowpack at mid and upper elevations. Rapidly accumulating and drifting heavy snow is in the process of creating a heavier slab layer on top of the weak base, and worsening avalanche conditions have already become very dangerous in the backcountry around Logan.

  • So far, it's a very productive storm water-wise, with the Ben Lomond Snotel reporting a gain of almost 4 inches of water in the last 24 hrs.
  • The Tony Grove Snotel at 8400' reports 14 inches of new snow in the last 24 hours, containing 2.4" of water. It's 19 degrees this morning and there's 54 inches of total snow now containing 94% of average water content for the date.
  • The CSI Logan Peak weather station recorded overnight average southwest wind speeds in the upper thirties, with gusts in the mid sixties and it's 13 degrees at 9700'.


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 yesterday 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)

***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

A slab layer consiting of settled snow from last week and drifted fresh snow from yesterday, overnight, and today is overloading existing widespread very weak faceted snow, and we are entering a very dangerous and scary period in the backcountry. Dangerous persistent slab avalanches are likely in drifted terrain at upper and mid-elevations, and heavy snowfall and drifting today will cause the danger to increase and become more widespread. Natural activity is most likely during periods of particularly heavy snowfall and/or extensive drifting, and dangerous and destructive humman triggered avalanches are likely on steep slopes, many of which have just or are about to reach the tipping point.

***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 might 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

Deeper hard slab avalanches, also failing on weak faceted snow in the basal layers of the snowpack are possible in drifted upper elevation terrain. The continuing storm will only cause larger and more destructive avalanches and the danger to rise and become more widespread.

weather

The National Weather Service in Salt Lake City has continue a Winter Storm Warning for the mountains of SE Idaho and Northern Utah. We can expect periods heavy snowfall and sustained fairly strong west-northwest winds today, with temperatures dropping below 20 degrees this evening. Snowfall and sustained west wind will continue tonight, and the current forecast calls for 8 to 16 inches of accumulation by tomorrow morning. Significant additional snowfall and increasingly windy conditions are expected to continue in the mountains through late Wednesday.

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.