Flathead Range & Glacier NP

Problemi valanghivi

• 

  Loose Wet

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Likely

  Dimensione

  1.5–3

  Dangerous natural and rider-triggered loose wet snow avalanches are likely on steep slopes around the compass today, including at upper elevations. These are likely to run far, particularly in confined gullies. Their wet, heavy debris will be very difficult to escape. These slides will be most widespread on steep slopes capped with cornices or under rocks that shed snow.

  Timing may be an inadequate risk-reduction tactic today, thanks to the inversions that developed overnight. Refrozen snow in a valley bottom does not indicate the same up high, where temperatures have remained above freezing and into the 40s. A mild greenhouse effect may have primed shaded slopes - so far immune to the wet snow hazards - by warming and wetting heretofore dry surface snow. 

  If you're hunting dry snow or attempting a summit, have multiple route plans that allow you to hopscotch between individual slopes where the snow remains cool or refrozen and that aren't exposed to overhead hazards. That will be tricky on foot but easier on a snowmachine.

  In general, move off of steep slopes where the surface snow is wet and you see rollerballs are fanning out downslope. That may mean scuttling to a more shaded slope, a higher slope, or pulling the plug and heading home. Plan a route back to the trailhead that's free from overhead hazard. Slopes where snow is dropping off trees or rocks into wet surface snow are prime candidates for wet snow avalanches.

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alta quota
  • Limite del bosco
  • Sotto il limite del bosco

  Probabilità

  Unlikely

  Dimensione

  2–3

  It's Big Slab Powerball on steep, upper-elevation slopes today. More entries - large triggers like falling cornices and large, wet snow avalanches - than the past week or two. Probably only one or two losing tickets: avalanches that release on the deeply-buried but still present January Drought Layer.  

  If you're traveling on or under steep, leeward, upper elevation start zones today, you've bought a ticket in this lottery. Like most games of chance, the probability of having the chosen entry is small. Tiny, perhaps. But not zero. 

  Either avoid this terrain, or do what you can to make sure you don't have the wrong combination of numbers. Scan the terrain around you and above you as you travel today, paying particular attention to steep, leeward, upper-elevation start zones. Look for gaps in cornices where chunks have fallen off, or where you see rollerballs fanning downslope. Look for old, partially filled crowns - these indicate that large slabs have already released on the JDL, so another slide there is far less likely. Avoid traveling on wind-swept slopes where the snow surface is peppered with rocks; this clue can indicate variable snow depths where a person's weight or a large trigger is more likely to collapse the JDL.