Forecast for the Logan Area Mountains

Toby Weed
Issued by Toby Weed for
Friday, December 28, 2018
MODERATE: Heightened avalanche conditions exist on drifted upper and mid-elevation slopes, and you could trigger avalanches involving wind-drifted snow. After last night's easterly wind, avalanches are possible in unusual or unexpected places. The snow is stable and the danger LOW in sheltered terrain, at lower elevations, and anywhere the snow was not recently drifted. You'll find excellent shallow powder conditions in the backcountry, but expect very cold temperatures, with wind chills well below zero.
  • Avoid slopes with stiffer, recently drifted snow.
  • Evaluate snow and terrain carefully.
Low
Moderate
Considerable
High
Extreme
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Weather and Snow
Quite cold in the mountains this morning, but we may see a bit of sunshine by afternoon. You'll find excellent shallow powder conditions in the backcountry, but easterly winds overnight created heightened avalanche conditions on drifted upper and mid elevation slopes. Shallow human triggered avalanches involving wind drifted snow are possible and perhaps likely in some places. East winds can create drifts in unusual or unexpected places, and these can be particularly devious in the Logan Zone.
Fine shallow powder riding conditions and mostly stable snow in the Logan Zone, but heightened avalanche conditions exist where light snow was drifted by east wind overnight.
The Tony Grove Snotel at 8400' reports 3 inches of new snow with .1" SWE in the last 24 hours, mostly from yesterday evening. It's a bone chilling 6º F and there's 40" of total snow containing 85% of average SWE. It's -1º F at the 9700' CSI Logan Peak weather station, and east-northeast winds are currently averaging about 22 mph, with gusts in the 40s.
We'll see clearing skies and perhaps even a bit of sun today as the low pressure system gradually moves away from the area. High pressure will return Saturday before another storm system impacts the area Sunday into Monday. Expect a high temperature at 8500' near 14º F and 11 to 15 mph east wind, veering from the north in the afternoon. Wind chill values will be as low as -14. It'll be partly cloudy and cold tonight. Low temperatures around 2º F, and 11 mph north wind will cause wind chills around -15. It'll be partly sunny tomorrow, with a chance of snow in the afternoon. High temperatures near 20º F and 15 mph south wind becoming west by afternoon are expected.
Recent Avalanches
No avalanches were reported recently in the Logan Zone.
There were two scary close calls in the Central Wasatch Range near Salt Lake City on Boxing Day, (12/26). A skier was completely buried except for his hand, but quickly rescued by his party in American Fork Canyon...report is HERE . Ice climbers were hit by an avalanche in lower Hogum Fork in Little Cottonwood Canyon, but managed to stay attached to the ice as they were overrun by soft snow....report is HERE
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Avalanche Problem #1
Wind Drifted Snow
Type
Location
Likelihood
Size
Description
Heightened avalanche conditions exist on upper and some mid-elevation slopes, and you could trigger avalanches consisting of wind drifted snow. Drifting occurred in exposed terrain much of last week, and there are some deeper hard wind slabs lurking under the fresh snow in places. East-northeast winds last night built fresh drifts at upper elevations in perhaps unexpected or unusual places.
  • Watch for and avoid fresh or older drifts on the lee sides of major ridges and in and around terrain features like cliff bands, scoops, gullies, stringers, and sub-ridges.
  • Avoid steep slopes that have a smooth, rounded appearance, or that sound hollow like a drum.
  • Hard wind slabs have a nasty tendency to let you get well out on them before releasing.
  • Cracking in the snow is a red flag indicating potential instability.
Avalanche Problem #2
Persistent Weak Layer
Type
Location
Likelihood
Size
Description
Although quite unlikely, dangerous human triggered hard slab avalanches failing on a persistent weak layer near the ground called depth hoar remain possible on isolated upper elevation slopes. Avoid very steep slopes with poor snow structure, including shallow, shady, or rocky terrain at upper elevations.
The shallow snow on the ground in many areas has become loose, sugary, and faceted in the past couple weeks. I've found particularly weak snow at mid and lower elevations in the backcountry, anywhere where the total snow is fairly shallow. In many areas, weak faceted snow near the ground is capped by a crust and a few inches of Christmas powder... Lacking a slab of stronger snow on top, the sugary snow is currently stable despite it's weakness.
Sugary, faceted snow from Thanksgiving creates a persistent weak layer near the ground on slopes with shallow snow cover. This from 12/20/18, on a west facing slope at 8500' on Beaver Mountain's backside.
Additional Information
I will update this advisory tomorrow morning.
General Announcements
The new UAC IOS mobile app is now available on the app store. Check out the new "My Weather" feature. HERE
Check out the new free online avalanche course series developed by the Utah Avalanche Center. This is a great way to refresh your skills or prepare you for a Backcountry 101 or Level 1 class. HERE
Now is a great time to practice companion rescue techniques with your backcountry partners. Here is our practice video.
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This advisory is from the U.S.D.A. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.