Advisory: Logan Area Mountains 	
Issued by Toby Weed for January 11, 2014 - 6:34am

There is a HIGH or Level 4 danger, and avalanches are likely on drifted upper and mid elevation 
slopes in the backcountry. Dangerous avalanche conditions are developing or exist in some areas at 
lower elevations as well. Dangerous triggered wind slab and persistent slab avalanches are likely 
on steep drifted slopes, and natural avalanches are quite possible. Large natural avalanches will 
become likely overnight, with another bout of strong winds and heavy snow forecast. Avoid travel in 
avalanche terrain today, stay off of and out from under steep slopes and obvious or historic 
avalanche paths.

THIS AVALANCHE WARNING IS FOR THE MOUNTAINS OF NORTHERN AND CENTRAL UTAH, TO INCLUDE THE WESTERN 
UINTA MOUNTAINS. VERY DANGEROUS AVALANCHE CONDITIONS EXIST THROUGH THE WEEKEND...AVOID BEING ON OR 
BENEATH STEEP MOUNTAIN SLOPES...AS AVALANCHES MAY BE TRIGGERED LOW ON THE SLOPE AS WELL. THIS 
WARNING DOES NOT INCLUDE SKI AREAS OR HIGHWAYS WHERE AVALANCHE CONTROL IS NORMALLY DONE.

The Tony Grove Snotel at 8400' reports close to two feet of new snow in the last 48 hours, 
containing 1.9 inches of water. It's a balmy 28 degrees this morning, and there is 49 inches of 
total snow containing 77% of average water content for the date. I am reading more reasonable west 
winds this morning at the UDOT Hwy 89 Logan Summit wind sensor, after sustained high winds for 
several hours yesterday, with 40+ mph average west winds and gusts close to 60 mph. The 9700' Logan 
Peak weather station reports 23 degrees, and southwest winds in the upper teens. Very dangerous 
avalanche conditions exist in the backcountry, with drifted and inverted heavy new snow, difficult 
trailbreaking, and safe riding limitted to lower angled meadows and packed trails. The heavy new 
snow is being drifted onto slopes with widespread very weak preexisting sugary or faceted snow.

There were several large natural and triggered avalanches across the Utah backcountry yesterday, 
with avalanches stepping down into weak basal layers. 

Locally; I cracked out a few wind slabs and collapsed a couple sizable cornices on drifted test 
slopes in the backcountry near Beaver Mt. yesterday. 

Avalanche Problem 1

Very dangerous wind slab avalanche conditions exist in exposed upper and mid elevation terrain, and 
the danger will increase and become more widespread overnight as more snow accumulates and is drifted 
by sustained strong west winds. Triggered wind slab avalanches and large cornice falls are likely on 
steep slopes with recent deposits of drifted snow, which are widespread across the region. Wind slabs 
generally form on the lee side of exposed ridge lines, but can also form on any slope aspect, 
especially in and around terrain features like gullies, scoops, sub-ridges, rock outcroppings, and 
cliff bands. Avoid steep slopes with recent wind deposits, which are often smooth, rounded and 
chalky looking, and can sound hollow or drum-like. It is possible that a wind slab avalanche could 
step down into weak old snow, producing a larger more dangerous avalanche.

Avalanche Problem 2

Dangerous human triggered avalanches failing in old weak faceted snow or in the basal layers of the 
existing snow pack are likely on slopes with poor snow structure, especially in drifted upper and 
mid-elevation terrain. I've found very weak preexisting faceted snow to be widespread in the 
Logan Zone, and it plagues slopes at all elevations, so we'll find a danger of persistent slab 
avalanches pretty much anywhere a significant slab layer consisting of more cohesive snow develops. 
Warmer temperatures, possible rain and continued drifting may lead to increasing danger today, and 
as cohesive slab layer forms, it is becoming more likely that you could trigger avalanches remotely, 
from a distance, or worse, from below. Audible collapsing or whoompfing is a significant red flag 
indicating serious persistent slab avalanche potential. Recent drifting and rapid accumulations, 
cracking, and perhaps natural avalanches are other red flags to take heed of today. An energetic 
storm overnight and tomorrow will cause the danger of persistent slabs to rise further still and 
become even more widespread.

We'll see a bit of a break in the stormy weather in the mountains today, but west winds will 
continue and strengthen ahead of the next energetic wave of storminess, which will begin to affect 
our area this afternoon. Expect 8500' high temperatures around 35 degrees, and a period of 
pre-frontal rain is likely below around 7500 this afternoon. Snowfall will increase tonight and 
continue tomorrow, with westerly winds remaining in the strong category. 6 to 14 inches of 
accumulation is forecast by tomorrow evening. A high pressure system will gradually build over 
our region as we head into the work week.