Observation: NWAC Observer

Advanced Information

Weather Summary

Clear and mostly calm, with some terrain features channeling very light easterly flow, which did not transport any surface snow. With a F to 4F upper snowpack, much snow could be available for transport, should the winds choose to blow. A well-shaded thermometer read 30F in the alpine on a southerly aspect, while a north-facing slope of similar elevation was holding an air temp around 20F.

Avalanche Observations

Map of listed avalanches: Avalanche Observation Comments:

No new avalanches observed. Noteworthy outliers exist (now >72hrs old), some of which have already been reported by friends and colleagues. Among these are some isolated pockets on Kangaroo Ridge that appear deeper-than-mere-windslabs.

Snowpack Observations

On a solar slope at 6800', a profile had a depth of 135cm. As observed by others, the recently buried Dec.9 surface hoar was visually discernible in the pit wall, but proved unreactive to tests (and non-problematic on the slope scale while traveling on skis). It seems that the SH is essentially being absorbed by adjacent soft layers, as it decomposes. The mid-late November crusts and facets (down about 70cm) were also unremarkable in small and large column tests. This layer, which poses a legitimate concern in many surrounding regions to our north and east, does not seem to present a widespread problem around WA Pass. Today, I observed new growth of 1-2mm surface hoar on a weak sun crust, likely formed on Dec.11. This SH was likely destroyed by the sun by midday, as the uppermost 10cm of the snowpack became moist. We can probably expect many iterations of crust formation and surface hoar growth in the coming days on solar slopes.
South-facing slopes, though no longer blower, offered smooth skiing by mid-day with some surface warming.

On a polar aspect (due N at 7400'), a profile had a depth of 155cm. I found no layers of concern in the pit. The November interface presented as a 5cm thick P-hard layer of rounding facets over a few cms of 4F hard facets. The layer was down about 70cm in the pit and unreactive to tests. Lower on the slope, I observed surface hoar between 5-10mm in size, up to about 6000' in elevation.
Very good ski quality.

Avalanche Problems

No problems observed today. One sz.1 windslab from Blue Lake Col was the most recent looking activity and is now > 48 hrs old and previously reported by other observers.