X
Avalanche Danger Rose: this graphic represents an avalanche forecaster's idea of how the avalanche danger exists across the topography in a given region. It is not a map...it is an idea. Picture it as a cone-shaped mountain viewed from above, built of three elevation bands; the outer ring represents low elevations, the middle ring represents middle elevations, and the innermost circle represents high elevations. Each elevation band is divided into sectors that represent the slope aspect (N-NE-E-SE-S-SW-W-NW). Each sector\'s color represents the avalanche danger rating assigned that day (see Avalanche Danger Scale).

In this example, the Avalanche Danger Rose depicts an avalanche danger rating of considerable on all high elevation aspects and on north to west-facing mid elevations; all other sectors possess moderate avalanche danger. The illustration depicts the spatial distribution of this forecast across a landscape.
X Wind Slabs: A relatively cohesive layer that forms when wind deposits snow on the lee side of ridges, gullies, and other terrain features. These slabs may be soft or extremely hard and can take up to a week to stabilize.
X
X
Avalanche Problem Rose: this graphic represents an avalanche forecaster's idea of the distribution of a particular avalanche problem across the topography in a given region. Picture it as a cone-shaped mountain viewed from above, built of three elevation bands; the outer ring represents low elevations, the middle ring represents middle elevations, and the innermost circle represents high elevations. Each elevation band is divided into sectors that represent the slope aspect (N-NE-E-SE-S-SW-W-NW). Sectors colored grey are thought to have the identified avalanche problem while white sectors do not.

In this example, the Avalanche Problem Rose indicates that a particular avalanche concern exists on all high elevation aspects and on north to west-facing mid elevations and that this concern is far less likely to be encountered on other aspects and elevations.
X Chance of Avalanches: This graphic depicts how likely you are to trigger avalanches or encounter natural avalanches while traveling on avalanche prone slopes. Unlikely means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. The chance of triggering or observing avalanches increases as we move up the scale. Certain means that humans will be able to trigger avalanches on many slopes, and natural avalanches should be expected.
X Size of Avalanches: This graphic depicts the potential size and destructive force of expected avalanches. Small avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become large enough to bury, injure, or kill people, large enough to bury or destroy vehicles and break a few trees, and large enough to destroy railway cars, buildings, or a substantial amount of forest. Historic avalanches are massive events capable of destroying villages and gouging or altering the landscape.
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LOW: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

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MODERATE: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

X

CONSIDERABLE: Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

X

HIGH: Very dangerous avalanche conditions. Travel in avalanche terrain is not recommended.

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EXTREME: Avoid all avalanche terrain.

Current Advisory
January 23, 2017 7:30 am by Ethan Davis

All Zones | Sawtooth Mountains | Smoky & Boulder Mountains | Wood River Valley | Soldier Mountains

Sawtooth Mountains

Bottom Line: The avalanche danger is CONSIDERABLE at upper and middle elevations. Rapid snowfall and wind-loading formed touchy slabs in many areas. Triggering a wind slab avalanche is likely on all wind affected slopes at any elevation. Slabs will be found in fewer locations at lower elevations and the danger is MODERATE. Fast-moving loose snow avalanches are likely in very steep terrain.

Primary Avalanche Problem

Wind Slabs   

Aspect/Elevation   

Certain
Unlikely

Chance of Avalanches   

Historic
Small

Size of Avalanches   

Wind slabs will be atop my problem list as I head out into the field today. Yesterday’s storm packed a punch. Wind speeds increased around midday with a frontal passage mixing moderate wind and strong gusts down into lower elevation terrain. Add in a dose of low-density snow and we’re left with touchy wind slabs in many areas. Yesterday, I observed rapid wind slab formation at exposed middle elevation terrain in the Smokys. SAC staff found similar conditions near Thompson Peak where 1-2’ thick slabs sat on a stiff crust.

Today’s avalanche problem has more to do with where the wind is (or was) than what elevation you’re at. The danger is higher at upper and middle elevations because there are more locations in these elevation bands where wind has created slabs. At lower elevations, slopes tend to be more sheltered from the wind and the slabs are fewer. The very important exception is where wind was channeled along the highway 75 corridor and moraines along lakes that jut out above the valley floor. Small naturally occurring slab avalanches were observed along the stretch from Galena Pass to Stanley and these slabs will continue to be sensitive to the weight of a rider. No matter where you choose to ride be on the lookout for obvious signs of instability like recent avalanches, cracking or collapsing. These are Mother Nature’s best clues that the snow you’re on is still unstable. Even small pockets of wind slab can have big consequences if they drag you through trees, over rocks or bury you in a gully.

Additional Discussion
Today, you may be able to trigger small, soft slab avalanches in areas that received a foot or more of recent snow and are sheltered from the wind. There is a complex variety of weak layers in and below our recent storm snow including: surface hoar, sugary facets, crusts, or crust/facet combos. Yesterday, observers near Banner Summit found a particularly sensitive layer of surface hoar on north through east-facing middle and low elevation sheltered slopes. Additionally, loose-snow avalanches are likely in very steep terrain. These slides start small, but gather speed and snow as they cascade downhill.

Weather Forecast

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

10 F 19 F 9 F

Cloud Cover

Overcast Overcast Overcast

Ridgetop Wind Speed

Light Light Moderate

Wind Direction

SE NE N

Snowfall

24hr: 3-6" 12hr: 1-3"
0-2" 0-2"

Avalanche Notes

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Mountain Weather Summary

A quick hitting storm moved through yesterday afternoon and evening. Snow accumulations were 3-6” in the Sawtooths and 5-9” in the rest of the advisory area. Mountain high temperatures reached the upper teens F and low-density snow was easily redistributed by moderate winds with strong to extreme gusts from the south and east.

Light snow will continue in some areas today with 1-3” possible near Galena Pass and Soldier Mountain. Daytime highs will reach near 20 F and light wind will blow from the northeast and east. Tonight, wind speeds will kick up again to blow moderate from the north while low temperatures dip near 10 F. Tomorrow’s weather will be similar to today with mostly cloudy skies and a slight chance for light mountain snow.

Sawtooth Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

10 F 19 F 9 F

Cloud Cover

Overcast Overcast Overcast

Ridgetop Wind Speed

Light Light Moderate

Wind Direction

SE NE N

Snowfall

24hr: 3-6" 12hr: 1-3"
0-2" 0-2"

Smoky & Boulder Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

11 F 19 F 6 F

Cloud Cover

Overcast Overcast Overcast

Ridgetop Wind Speed

Light Light Moderate

Wind Direction

E E N

Snowfall

24hr: 5-9" 12hr: 0-2"
1-3" 0-2"
           

Wood River Valley

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

15 F 23 F 10 F

Cloud Cover

Overcast Mostly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Light Light Moderate

Wind Direction

SE NE N

Snowfall

24hr: 5-8" 12hr: 0-2"
0-2" 0-1"
   

Soldier Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

11 F 18 F 10 F

Cloud Cover

Overcast Overcast Overcast

Ridgetop Wind Speed

Light Light Moderate

Wind Direction

E E N

Snowfall

24hr: 5-8" 12hr: 0-2"
1-3" 0-2"
           

General Information