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.
X

LOW: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

X

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.

X

EXTREME: Avoid all avalanche terrain.

Current Advisory
February 22, 2017 7:30 am by Scott Savage

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

Sawtooth Mountains

Bottom Line: A snowbiker was caught and partially buried in an avalanche in the Soldier Mountains yesterday. You remain likely to trigger slab avalanches in wind-loaded terrain today. Wind-drifts are largest and most widespread at upper elevations, resulting in a CONSIDERABLE danger. At middle and lower elevations, the wind features are more isolated and the danger is MODERATE. While stability is better in terrain not affected by yesterday’s wind event, human triggered slab avalanches and sizable sluffs are possible on some very steep slopes.  

Primary Avalanche Problem

Wind Slabs   

Aspect/Elevation   

Certain
Unlikely

Chance of Avalanches   

Historic
Small

Size of Avalanches   

Details are not yet available, but a snowbiker was caught and partially buried in an avalanche in the Soldier Mountains yesterday. In the past 24 hours, the mountains picked up another 3-8” of new snow while strong to extreme winds gusted over 70mph, raking many normally sheltered slopes. Winds blew hard enough to down trees in lower and middle elevation terrain and form large drifts in areas that are frequently dead calm. Professionals in the Soldier’s reported “trees recently blown down everywhere and 1 fallen tree started a small wind slab avalanche on a road cut...the entire area is totally wind effected.”  Ski patrollers at Baldy reported downed trees, cornices and drifts growing quickly during the day, and cracks shooting up to 15 feet in front of their skis. Expect to see a bizarre landscape of wind features in exposed terrain today, including another generation of 1-5 foot thick, soft and hard wind slabs. These fresh wind deposits lie above several generations of wind slabs that formed in previous days. You could find wind deposited snow anywhere and everywhere: near ridgelines, on the sides of gullies (cross-loaded areas), on aprons in the bottom of cirques, near prominent terrain features lower on slopes, and in places you rarely see wind effects. Huge cornices have grown on many ridgelines.  

How should we manage this problem? Avoid it. Stability - and riding and skiing conditions - is better on slopes not affected by recent winds. Seek out softer snow to decrease your risk. Loading patterns could be complex; pay attention as conditions may change over very short distances. Many of the wind drifts will be hard enough to support your weight without initially cracking but could eventually break well above you. Cornices have grown substantially this week and should not be trusted - give them a wide berth.     

Additional Discussion:
If you find an area not affected by yesterday’s impressive wind event, check for buried crusts or surface hoar in the upper 3 feet of the snowpack before committing to consequential terrain (slopes with trees, cliffs, or terrain traps at the bottom). The surface hoar and crusts will appear as obvious stripes in a snowpit (see photo in Media section). These layers are not widespread or overly sensitive, but avalanches could fail on them on very steep slopes. Large loose snow avalanches (sluffs) are also possible in very steep, sheltered terrain. When you’re pondering whether to ski or ride a slope, picture what would happen to you if it did avalanche. If that mental picture makes you cringe, maybe it’s time to move to less serious or gentler terrain.

Weather Forecast

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

16 F 27 F 11 F

Cloud Cover

Overcast Mostly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Strong Light Light

Wind Direction

W SW N

Snowfall

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

Avalanche Notes

Transcript from a podcast on the season snowpack and avalanche summary, recorded on Valentine’s Day, February 14:

This is Scott Savage from the Sawtooth Avalanche Center in Ketchum, Idaho with a snowpack and avalanche summary for the season to date through Valentine’s Day.

Seasonal snowpacks are like snowflakes in that they’re all unique, but this year has definitely been an outlier that will be remembered for years to come.  We got the season started with some October storms that left snow in upper elevation and shady middle elevation terrain by Halloween. High pressure in the first half of November led to some amazing fall mountain biking but didn’t help the snowpack much. The “snowpack”, if you want to call it that, was either dirt or an ugly crust facet combination. Facets are those weak, crumbly, sugary crystals that don’t stick together well and lead to persistent slab avalanches when they get buried.  In mid-November and early December, the weather turned much colder. Small storms moved through the area but only produced a handful of small avalanches in wind-loaded areas. Mainly, we created a thin, weak, faceted snowpack that was waiting for a load.

It sure got a load. Starting on December 8th, an unrelenting series of storms hit central Idaho. We had a widespread avalanche cycle in mid to late December with persistent and deep persistent slabs failing on the facets and crusts that formed in the fall. Many alpine paths ran full track with crowns in the 4-10’ range. After those early season weak layers had been flushed, wind slabs continued to run during storms on mid-storm weaknesses and on subtle faceted weak layers that formed during short dry spells in between the December and January storms. While none of those weak layers really jumped out at you, they were just weak enough to produce widespread natural activity given the barrage of storms hitting Idaho.

Through Jan 24th, the lower elevation snowpack was at near record levels, around 200-600% of normal in the Snake River Plain and south central Idaho mountain valleys. Both Ketchum and Stanley had exceeded their seasonal snowfall averages already, totaling around 120” by Jan 24th. We enjoyed a roughly 1.5 meter deep snowpack in the valleys, easy access everywhere, and “off the hook” riding and skiing conditions.

We began February with a 10 day prolonged storm cycle, including multiple atmospheric river events. So what is an atmospheric river? It’s a long, narrow ribbon in the atmosphere that carries lots of water. On average, they are about 250-400 miles wide. On satellite images, they actually look like rivers. A typical atmospheric river carries an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. You get the idea – when an atmospheric river hits a major mountain range, it’s going to dump in a big way. We got 7-12” of water in 10 days, and the storm finished with a big bang. The last couple inches of water fell as rain to about 8000-9000 feet, setting off an impressive wet avalanche cycle in the valleys. Avalanches took out mature timber, putting it in dog walking parks, people’s back yards, and in rivers. At the same time, several feet of snow fell in the alpine and produced large natural wind slab avalanches up to a mile wide.

Over the past 2 months, our middle elevation weather stations recorded 20-27” of water (SWE). That’s translates to about 200-300” of snow. In the past month alone, we picked up 14-18” of water and about 140-200” of snow. The Sawtooth Avalanche Center issued 2 EXTREME danger ratings, 19 HIGH danger ratings, only 13 days with MODERATE danger, and a single day of LOW danger. We had never issued an EXTREME danger rating before this season. Typically, we’ll see 1-5 days each year with HIGH danger ratings...this season’s 21 days of HIGH or EXTREME danger is unheard of.  We’re already looking forward to checking out the destroyed timber and avalanche carnage this summer when we’re out riding bikes and hiking beneath the large avalanche paths in the mountains.  

So that’s the past; where does that leave us now? The rain event last week saturated the entire snowpack below about 7500 feet, so lower elevations have done their thing and can probably handle just about whatever Mother Nature may throw at them. Stout crusts formed on all aspects below about 8000’ and on many SW through SE facing slopes. We do have some thinner crusts, near surface facets, and possibly isolated surface hoar that has grown on some partially shady and shady aspects, but strong temperature inversions have held those processes in check by keeping upper elevation temperatures in the 20’s to 40 F during this dry spell. We will probably have some issues develop at the interface between the current surface and future snowfall, but we’re not seeing any widespread weak layers below the current snow surface.

What’s the crystal ball saying for the week ahead? With another series of atmospheric river events forecast to hit us from Thursday, Feb 16th on, we’re anticipating widespread wind slab avalanche activity in exposed terrain and possibly some storm slab avalanches in sheltered terrain where more than about a foot of snow accumulates. Avalanche activity should be focused on the prime time 37-45* slopes. We expect the warm, fluctuating temperatures to create short lived, mid-storm weaknesses that heal pretty quickly. By quickly I mean heal in a couple days instead of weeks.  The strong February sun will cause periods of wet loose avalanche problems on sunny aspects following storms when skies clear.

For the longer term view: On the whole, we have an unusually deep, strong snowpack that will keep us skiing corn for months even if it were to quit snowing now. But hopefully it doesn’t quit snowing now.

Thanks for tuning in. Check out our website at sawtoothavalanche.com for more information on conditions in south central Idaho.

Mountain Weather Summary

SNOTEL stations are not currently reporting data, but most mountain locations appear to have received 3-8” of snow in the past 24 hours. Strong to extreme winds raked the mountains Tuesday before gradually diminishing in the afternoon. Mountain temperatures cooled from morning highs near freezing to the 20’s F by sunset. Overnight, light snow showers continued, W/NW winds blew at light to moderate speeds, and temperatures dipped to the teens F.

Today, we should get a bit of a break from the wet and windy pattern as a storm passes to our south. Expect partly to mostly cloudy skies with stray showers depositing up to an inch of snow in some locations. Temperatures reach the teens to 20’s F while moderate W/NW winds blow on the ridgetops.

Tonight, scattered showers deposit 1-3” of snowfall, temperatures cool to the single digits and teens F, and moderate N winds blow on the ridges. Unsettled weather and cooler temperatures persist this week.

Sawtooth Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

16 F 27 F 11 F

Cloud Cover

Overcast Mostly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Strong Light Light

Wind Direction

W SW N

Snowfall

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

Smoky & Boulder Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

10 F 18 F 9 F

Cloud Cover

Obscured Mostly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Moderate Light Moderate

Wind Direction

W NW N

Snowfall

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

Wood River Valley

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

13 F 23 F 14 F

Cloud Cover

Obscured Partly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Moderate Moderate Light

Wind Direction

NW NW E

Snowfall

24hr: 3-8" 12hr: 1-3"
0-1" 0-1"
   

Soldier Mountains

Last Night
5PM - 5AM

Today
5AM - 5PM

Tonight
5PM - 5AM

Temperature

12 F 21 F 10 F

Cloud Cover

Obscured Mostly Cloudy Mostly Cloudy

Ridgetop Wind Speed

Extreme Strong Strong

Wind Direction

W W N

Snowfall

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

General Information