Whumphing in Hollywood Bowl Area

Submission Info
Tuesday, January 9, 2018 - 1:00pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
37° 36' 2.88" N, 119° 1' 39.36" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up the low angle ridge between Hollywood Bowl and Red Cone Bowl to test our persistent weak layer. We got lots of feed back from the layer buried on 1/4 and the rain crust that was buried on 1/6, mostly with our ears and feet. We heard and felt collapsing and whumphing in many places today. Probably the biggest event of the day was one slope scale whumphing event on a 50' tall 30deg incline opening in the trees that also produced long (50') shooting cracks. The slope was supported below, but that may be the only reason we did not trigger and actual slide. Snowpack tests at 9400' on a 21deg slope facing NNW showed some potential for fracture initiation in the weak layer: CT22 SP x2 in the facets that lie just a few inches under the rain crust, buried 62cm down here under old wind deposits. However, other results in that location were mixed: CT3 RP x2 down 10cm at an interface between new snow and a previous wind deposit, CT12 RP x2 down 18cm in an interface between wind deposits. PST to test the weak layer at 62cm had no results. ECTN 12 and ECTN20. The layer of concern was found buried 30 to 40cm down under storm snow from 1/6-today, and also 65+cm down in places where the wind had blown since 1/6. Hand shears all along our route from McLeod Lake to under the Mammoth Crest had moderate to easy failures on the persistent layer with some failing on isolation. Test slopes had limited results with only short localized cracking. Bottom line, I think, is that things are tricky to manage out there right now and it's better to be safe than to rely on being lucky.

Temperatures definately cooled with elevation today: Tair= 4deg C at 9000' at 1130am, Tair= -2deg C at 10,000' at 1350pm. Poor visiblity all day, could not see the Crest at all. Snow showers varied betwee very light to light (S-1 to S1).

Weather Observations
Blowing Snow: 
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