Avalanche Forecast
Issued: Mar 12th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
ghelgeson,
Avalanche Canada
East/Northeast wind Friday night into Saturday is expected to form another round of fresh wind slabs which will come to rest on a buried sun crust, these slabs may run faster & further than you'd normally expect. This adds to the damage done by southwest wind Thursday & Friday.
Summary
Confidence
Weather Forecast
Cool and crisp, Sunday looks like a beautiful late winter day.
FRIDAY NIGHT: Overnight low around -21C, light to moderate northeast wind, trace of snow possible.
SATURDAY: Broken cloud cover, daytime high around - 14 C, strong east/northeast wind, 1 to 3 cm of snow possible.
SUNDAY: Clear skies, daytime high around -13 C, light variable wind, no snow expected.
MONDAY: Scattered cloud cover, daytime high around -5 C, strong south/southwest wind, no snow expected.
Avalanche Summary
Fresh wind slab avalanches were quite sensitive to triggering as observed in this MIN report from Thursday. Wind slabs also released naturally on Thursday.
Last weekend our field team was in the Wheaton. They observed avalanches to size 2.5 on south facing slopes, starting high on ridges and rolling well into and through the trees. See a couple of MIN posts here and here.
The term 'Wheatonesque whumpfs' is worth holding onto. Remember that a whumpf is an avalanche that tried, with one key ingredient missing -- slope angle. Whumpf the right terrain and you've converted it into the real thing, hopefully it's not rolling down ontop of you.
Snowpack Summary
Almost 20 cm fell Thursday into Friday which adds to the 10 to 15 that fell earlier this week. You can stay up to date with snowfall with the Fraser Camp Wx Station which is back up and running. All the new snow has been subject to strong southwest wind which has formed wind slabs that were quite touchy on Thursday. The wind is expected to switch to the east/northeast Friday night into Saturday which will add further insult to injury to our powder riding dreams.
The Wheaton's continental snowpack is the kind of thing you'd find around Jasper or Kananaskis Country in the Rockies. It's a weak snowpack dominated by sugary facets and depth hoar, the icing is either layers or a fat cap of harder cohesive slab. It's an untrustworthy structure that requires really good terrain selection and travel habits, or a healthy dose of luck.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Recent new snow may be hiding windslabs that were easily visible before the snow fell.
Problems
Wind Slabs
Previously strong southwest winds have redistributed all the recent snow into widespread wind slabs. Wind is expected to shift to the east/northeast Friday night into Saturday which will form another round of slabs. The catch is that these new slabs will form above a buried sun crust which could allow them to run faster and further than expected.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 13th, 2021 4:00PM
