Got In. Got It. Got Out.

Went to the Flathead Range today to monitor the start of the storm and look at the layers of facets buried where the snowpack is shallowest. 

• We saw increasing snowfall rates. Very light snowfall throughout the morning began to pick up around 1pm. By 330pm we noticed moderate snowfall. 
  • 1 inch of very low density new snow fell by our exit at 4pm. The new snow sat atop 3-6 inches of soft recent snow.
  • In open terrain above about 5800 feet the new and recent snow sits on old, hard wind slabs.
  • We tested many steep slopes and got minimal sluffing. On one short, north-facing, 45 degree pitch we we able to trigger a loose dry avalanche that entrained the recent snow.
  • We saw 5 more small sluffs in steep chutes we expect were about 24 hours old.
• We experienced increasing wind and blowing snow.
  • When we got above 6000 feet around 11am southwest winds were light to moderate with occasional strong gusts. We saw puffs of blowing snow. By our exit winds were moderate and blowing snow was consistent. 
  • We found many ridgelines with wind-affected snow and fresh cornices. Mostly of these were stubborn - not breaking wider than our skis with kicking. None of the ones we kicked triggered more than very small sluffs on the slopes below.
• Temperatures were rising.
  • We took air temperature at 10am: 1 deg F. When we took it at 345pm at about the same elevation: 12 deg F.
  • The rising temperature was having the subtle effect of consolidating the new and recent snow. We did a shovel tilt test and the surface snow slid off harder snow below with only one "baby burp."
  • We got just enough cracking in the new and recent snow to clue us in that it was starting to form a slab.
• We tested a layer of buried facets from mid-December at lower and middle elevations where the snowpack was shallowest. We got no propagating results.
  • The facets are bigger, looser, and more developed than I have seen them before. They're 1-2 feet below the surface depending on elevation.
  • Below 4500 feet elevation the sugar rests above and below a hard crust from December 18th. Above that elevation, the crust is replaced by graupel, but the facets remain, sadwiched between 2 thin hard slabs.
  • We suspect that these weak grains will be a problem with a thicker, stiffer slab on top.

So, our takeaways: We have stiffer snow buried with a weak layer on top (either the low density recent snow, or the buried facets depending on location). The slab looks like it's coming tonight.