Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Our snowpack is saturated in most areas, and elevated temperatures, a poor overnight refreeze, and the possibility of rain up to 6,500 feet cause concern for dangerous loose wet avalanches today. Multiple large natural wet avalanches occurred yesterday. The possibility of similar activity continues. Choose slopes less than 35 degrees in steepness and free of overhead hazards.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3

    The cold front will likely help keep our rapidly melting snowpack from coming completely unglued again today. However, odds are that the freeze won't be deep enough to lock everything in place throughout the day. As the day's heat rises, the crusts that recently formed and the already saturated snowpack below will become cohesionless and cause concern for loose wet avalanches. Elevations below 7,000 feet lacked a refreeze last night. The southern reaches of our forecast area had the warmest temperatures. 

    Temperatures are forecast to reach the upper 40s for elevations below 6,000 feet and low-30s to mid-40s  for above 6,000 today. Freezing levels are expected to stay near 6,000 feet for the Seeley zone, 6,500 for Rattlesnake, 7,000 for the northern Bitterroot, and 7,500 for southern Bitterroot today. 

    Wet sloppy snow, sinking past mid-boot, and triggering wet sluffs on small, safe test slopes are signs that it is time to move to shadier aspects or exit avalanche terrain. Plan your day in the mountains so you are not crossing or beneath avalanche terrain. 

     

    03/28/2022 Jeff and Trask witnessed a very large wet avalanche yesterday.  This slide could have easily destroyed a single-family home (D3). The estimated slide path length was one mile long, 2400ft of vertical fall, and 600ft wide at the debris pile. It was triggered by a point realise from a cliff band near the summit that then stepped down to rock and ground. Photo: Trask Baughman

Avalanche Discussion

Since our last forecast, we've had elevated temperatures, and poor overnight refreezes. The elevated temperatures stuck around for over a week. Saying the snowpack is melting is a bit of an understatement. The snowpack was rapidly destabilizing and thoroughly saturated yesterday. It was easy to start large loose, wet avalanches in the Rattlesnake by tossing a single snowball. Large debris piles from loose wet avalanches up to D2 were strewn at the base of any south or east-facing avalanche terrain with more minor point releases on north and west aspects. In the Seeley zone, multiple large D2+ wet slides released yesterday as well as a witnessed D3 that stepped down as a wet slab near Sunday Mountain.

The SNOWTELs have been recording some impressively high temperatures in recent days. Stuart Mountain at 7400ft in the Rattlesnake and Saddle Mountain at 7940ft in the Southern Bitterroot stayed in the mid-40s to 50s from 10 am on Sunday until 5 pm yesterday. Temperatures reached the low 60s in the Jocko at 6330ft on Sunday and low-50s yesterday with only 2 hours in the low-30s Sunday night. SNOWTELs across the forecast area recorded low temperatures to only the mid-30s to low 40's °F on Sunday night and low 30s last night. 

Thankfully a series of weak storms are moving in from the northwest, allowing temperatures to moderate slightly.  Temperatures dropped to the low 30s after midnight with freezing levels near 7,000 feet last night. Rain showers have brought a trace amount of water so far. 

Wet slides should not be underestimated today. Our snowpack is saturated in many areas and any refreeze crusts are unlikely to be thick enough to bridge the cohesionless snowpack below. Areas with the thickest supportable crust may be safe while they remain frozen, but warm temperatures or rain will break this crust down. A softening surface crust is a clear sign to exit avalanche terrain. South and east-facing slopes that haven’t already released are most suspect.

Ski and ride safe.

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