Avalanche Discussion

www.turns-all-year.com/skiing_snowboardi...ex.php?topic=11576.0

With links to this presentation by NWS:

www.wrh.noaa.gov/sew/Dec20-21WinterStorm/player.html

Good info on avy danger, especially toward the last few slides (no pun intended)...

It's amazing how insightful it can be to walk around in the evolving event that shapes the forecast. We had the "opportunity" to walk around in the bitter cold of the northeast winds of Monday around Table Mtn., both north and south, and found that on eveything from northeast around east to southwest, walking near ridgetops under a little prominence that had a 30+ degree slope on it caused the newly slabbed fresh snow from Saturday (which on Sunday had been non-coalescent but now was wind-stiffened into a slab) to break above the skier and run on the ice crust. Once one entered below ridge levels, however, the north aspects were noncoalescent powder and stayed that way all week, with obvious slow bonding to the crust as the week went on. It will be interesting to see if this layer can still react that far down after the new cycle, though I expect probably it will be very unlikely. Just reinforces for me how awesome reports like the Rogers Pass report, from folks walking around in it and testing it every day, are.

NWAC:

If this were not enough for future concern, reports
Crystal Mountain from early Tuesday morning indicated
widespread surface hoar had formed overnight. If the
surface hoar gets buried by expected low wind snowfall
Tuesday night it may be a recipe for dangerous conditions
to develop once loaded by heavier denser wind deposited
snow expected in the near future!

Be careful, after this next storm, in the Crystal BC - dig your pits boys and girls

cd

I know everyone reads these without me reposting here, but the emphasis is mine:

Recent moderate snowfall has been received in most areas during the past few days. For the most part this recent snow is quite light and fluffy, and intermittent moderate winds have generally transported this onto lee slopes where mostly 6-18 inch soft slabs and considerable avalanche danger exist. These lee slopes are predominantly northeast to southeast exposures near higher ridges and west facing slopes near the passes. Weak layers within our still relatively shallow snowpack are many and very significant, ranging from buried surface hoar layers to intermediate or advanced facets to just really weak low density snow layers. This is perhaps the weakest snowpack structure that I have observed in late December for over 20 years, and many field reports of wading or wallowing in the snow at or near the ground when one steps off the packed trail seem to corroborate this assessment. The only positive aspects of the current snowpack in terms of BC avalanche danger is the relatively lack of cohesion in the near surface snow and the still relatively shallow depth that is allowing for some vegetation and terrain anchoring of this fragile snowpack below about 4 to 5000 feet.

Overall, our delicate snowpack is primed for a rapid and dramatic increase in the danger when loaded by heavier and more normal Cascade snowfalls. Unfortunately, in order to start putting the daily impact of these persistent weak layers of facets and surface hoar behind us, we need substantial loading by heavy dense snow, high winds and/or rain. Although this kind of weather is expected to arrive beginning later Friday and continue for much of Saturday, the current magnitude of frailty that our snowpack embodies may take many such storms to build a strengthening bridge over these buried weaknesses...and even then these flimsy layers may re-emerge as problems next spring. In short, this weekend and especially Saturday may be an excellent time to risk your health away from the mountains by shoveling your walk, exchanging your gifts at the mall, or trying out some new high-tech lowland gear.

Good point lordhedgie, I just read the forecast today and was going to add the same thing to this discussion - be careful out there! I'll likely hit the resort this weekend, and will probably carry my avy gear.

I dug a quick pit on Hyak around 7:30 this morning. I'm not very scientific but a littler under two feet of loose snow on top of packed snow is what I saw. It didn't take much to get all of the loose snow to slide in the pit, basically just sliding the shovel behind the block and it went. I had a fun low angle run and didn't oberve anything sliding as I skied out. The highway thermometer was at 29 F when I left. Hyak is groomed to the top which made access a breeze. I did snag the top of a lil christmas tree which sent me into a beauty of a face plant.