BC Zone Observation Report
Tuesday, January 1, 2019 at 12:00 AM
Ridgeline Wind Speed:
Most Significant Precip Rate:
S-1 - < 1 cm/hr
Scattered showers off and on all day, but no accumulation. Remarkably calm. Cold.
Very soft surface conditions, with powder on high ground that typically gets blown clean with even light winds. Definitely no Wind Slab avalanche concerns observed along Anthracite Mesa. It's possible wind slabs built above treeline, but not at the near treeline elevation. Persistent Slab avalanche structure is not profound and getting more complicated. Test results were mixed throughout the day, with numerous tests on a variety of aspects. North, northeast, and east produced no results on slopes with prior drifting and more than about 120cm total depth. Numerous cornice stomps on steep ground produced nothing. But, at lower elevations it was easy to trigger facet sluffing in weaker areas further down valley where the total snowpack was less than 100cm. Very little change in HS makes for huge differences in structure, test results, and the likelihood of triggering an avalanche. Southeast, south, and west all produced cracking on steeper slopes that held snow earlier in the season (these had a height of snow >70cm). The snowpack appeared a bit hung over from getting loaded on New Year's Eve. 15-20cm of very low density new snow seems to have been enough to make the snowpack quite grumpy and noisy. There still isn't any stiffness to the slabs, but old crusts are serving to propagate cracks with roughly 1-1.5" of water weight load over those crusts supported by a layer Fist-minus facets that were buried on December 19th.
Triggered one small sluffs in steep shady terrain. Observed two small natural avalanches off Gothic's West Face.
AS / c
Steep gullied features
Average Slope Angle:
O - Within Old Snow
Weak Layer Grain Type:
These cracked at the surface like a soft slab, but did not propagate at all. In motion, they poured down the slope with facets visibly flowing under the new snow.
Gothic West Face