Avalanche Advisory
Advisory: Logan Area Mountains Issued by Toby Weed for Thursday - December 17, 2015 - 6:57am
bottom line

HIGH (level 4): Very ​dangerous avalanche conditions exist on drifted slopes at upper elevations in the backcountry, and natural avalanches are likely or occurring today. You are likely to trigger dangerous avalanches in drifted terrain at upper and mid elevations. Avoid travel on or below slopes steeper than about 30 degrees and obvious or historic avalanche paths.
avalanche warning

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

  • * TIMING...THROUGH 6 AM FRIDAY MORNING.
  • * AFFECTED AREA...THE NORTHERN MOUNTAINS INCLUDING THE WASATCH...THE LOGAN AREA MOUNTAINS...AND THE WESTERN UINTA MOUNTAINS...THE MOUNTAINS OF SOUTHEAST IDAHO
  • * AVALANCHE DANGER...HIGH WITH NATURAL AVALANCHES OCCURRING.
  • * IMPACTS...RECENT SNOWFALL AND STRONG WINDS HAVE CREATED A HIGH AVALANCHE DANGER.
  • TRAVEL IN AVALANCHE TERRAIN IS NOT RECOMMENDED. 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

Dangerous avalanche conditions exist today in the backcountry. The danger is HIGH and natural avalanches are likely or occurring this morning in drifted terrain at upper elevations. The Tony Grove Snotel at 8400' reports 13 inches of light snow overnight, containing .8" of water. There's 40 inches of total snow at the site containing 69% of average water content for the date. West winds increased last night during periods of heavy snowfall, easily drifting the light snow, with the UDOT Hwy 89 Summit weather station recording average wind speeds in the mid twenties and gusts of around 40 mph. The CSI Logan Peak weather station is currently reporting single digit average NW wind speeds and a chilly 2 degrees at 9700'.

Very weak faceted snow is widespread at mid and upper elevations in the Bear River Range, and it's now capped by a rather inconsistent rime or rain-crust and up to around a foot of light powder. Wind and accumulating snow are creating a heavier slab layer on top of the loose faceted snow.

Loose faceted snow crystals plague the shallow snowpack in the Logan Zone. (12-15-2015)

The shallow snow is quite weak across the Logan Zone and in the Providence Canyon where I found fist-hard snow from top to bottom. (12-15-2015)
recent activity

Ski areas in the Ogden and Salt Lake Area mountains report more activity from control work yesterday, with a few triggered avalanches going pretty big, stepping down to the rocks, and involving old sugary snow in the basal layers of the snowpack. No avalanche activity has been reported in the Logan backcountry recently.
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

***Pay close attention to signs of unstable snow like whoompfing 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!

Very weak faceted snow is widespread across the zone at mid and upper elevations. Last night's west wind and significant accumulations of easily drifted light snow was probably enough to overload the very weak basal snow on many slopes, and both triggered and natural persistent slab avalanches are likely, especially in drifted terrain at upper elevations... There is a HIGH danger and you should avoid travel on or under all slopes steeper than 30 degrees in the backcountry today.

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

West winds picked up overnight and there was lots of nice light powder on the snow surface and falling, so drifting certainly occurred and will be ongoing today in upper elevation terrain. Wind slab avalanches are likely to become more sensitive to human triggering as the slabs continue to build, and they may step down into weak basal snow near the ground or pull out a persistent slab in descent. Avoid travel in or below steep drifted terrain today....

weather

Snow is possible in the mountains today, mainly in the afternoon, with west winds averaging in the mid teens. At 8500' high temperatures of around 18 degrees F are expected. Snow is likely again tonight, with temperatures rising to around 30 degrees, stronger southwest wind, (gusts in the 30s) and a possibility of 3 to 5 additional inches of accumulation. Unsettled, somewhat stormy weather will continue through the weekend, and there's potential for a more significant storm (with lots of water or heavy snow) early next week.

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.