Banner Summit

The chance of avalanches will peak on Monday and then decrease with cooler temperatures / wind / cloud cover Tuesday afternoon through Thursday. Some details:  

Wet Snow Avalanches:  Monday's hot, sunny, calm weather will continue pushing liquid water into the snowpack. Avoid any steep slopes where you're sinking into a wet, mushy, unsupportable snowpack, and slopes where you experience snowpack collapsing. The time windows for frozen, supportable crusts could be brief or non-existent.  Have a plan B in case the snowpack is a sloppy mess where you planned to ride or ski. Don't linger under large avalanche paths while they are baking in the sun; wet avalanches frequently release naturally, on their own.  

• Wet Loose: Professionals reported widespread natural wet loose avalanche activity on sun-drenched aspects in the northern Sawtooth Mtns over the weekend. Most of the avalanches appeared to involve only the recent storm snow and were small, but some were large enough to bury people. Given the weak or non-existent freeze Sunday night, expect more wet loose slides with Monday's sunshine, heat, and light wind. Wet loose avalanches are most likely on very steep, wind protected upper and middle elevation slopes while they directly face the sun. The threat of these avalanches follows the sun around the compass, beginning on E-SE facing slopes in the morning,  moving to S-SW aspects midday, and ending on W-NW facing slopes late afternoon and evening. Watch for rollerballs and pinwheels,  signs the snow surface is wet. 
• Wet Slabs: On many shadier (NW-N-NE-E) alpine and upper elevation slopes where the total snow depth is more than about 4 feet, the snowpack has not yet transitioned to a well-drained, "summer" snowpack; liquid water has not reached all of the faceted weak layers that plagued us earlier this season. We don't expect widespread wet slab avalanche activity this week, but there's a chance of isolated, large, natural or human-triggered wet slabs on Monday and Tuesday. Accurately predicting when wet slab avalanches will release on individual slopes is challenging at best.  

Dry Slab Avalanches: Last week's storm formed slabs in alpine and upper elevation terrain, and several large avalanches released naturally on N-NE-E aspects in the Sawtooth and northwestern Smoky Mtns (see photos below). While the slabs have stabilized in recent days, we can't rule out triggering a large dry slab avalanche on very steep, shady, alpine slopes. If you're hunting for dry snow to ski or ride, watch for fresh cornices, dunes, and drifts, signs the wind was at work moving snow. Cracks shooting out from your boards or sled are clear signs you've found a slab. Large avalanches are unlikely where you find dry, powdery snow.   

Loose Snow: Large, natural and human-triggered, dry loose snow avalanches (sluffs) are not likely but worth mentioning. On what slopes are you most likely to see this?

• Very steep, shady alpine terrain
• Significant snow fell last week
• Sheltered from the wind

Recent Observations: 

• April 3rd - Copper Mtn, Banner Summit: CLICK HERE
• April 2nd - Frenchman Ck, Smoky Mtns: CLICK HERE

 

SNOWPACK AND AVALANCHE GENERAL INFORMATION

Some basic points to remember until you put the sleds and boards away for the summer:

• Spring weather can rapidly alter snow conditions and snow stability. Think minutes and hours rather than days and weeks.
• Storm slab and wind slab avalanches are most likely during and immediately following a storm. 
• Short periods of sunshine after a snowstorm can quickly create wet loose avalanche instabilities.
• Keep wet slab avalanches in mind, especially during rain events and when we go days without the temperature dropping below freezing. Many shady, upper elevation slopes have not yet gone through a "spring transition". Travel cautiously in this terrain when rain or hot, sunny spells push meltwater deeper into the snowpack. 
• Give cornices a wide berth and don’t linger beneath them. 
• Complicated, consequential terrain doesn’t get less complex or serious in the spring and summer. Respect the mountains, maintain safe travel procedures, and keep your guard up.
  
  

OBSERVATIONS

Even though we’re done issuing forecasts, we’ll continue posting observations when we get out in the mountains. We encourage you to do the same. Please let everyone know what you’re seeing out there, especially if you see or trigger any avalanches. We’re always trying to collect as much information as possible about large wet slab avalanches (where, when, etc); let us know if you come across any of these beasts in your travels. There are several ways to stay connected and to share what you see:

Submit an Observation:

• CLICK HERE for the online form
• Download the Avy App: Apple | Android
• Email us: info@sawtoothavalanche.com
• Text us at 208-481-5921

View Observations:

• CLICK HERE to view Observations.
• CLICK HERE for details on recent Avalanches.
• CLICK HERE to view our Photos & Video page.