Eastern Sierra Avalanche Forecast - 1/9/15

Avalanche Advisory published on January 9, 2015 @ 7:00 am
Issued by Sue Burak - Inyo National Forest
advisory discussion

Mild daytime and night time temperatures are promoting lower gradients of temperature and vapor diffusion. Angular facets are rounding and forming clusters of small rounded and rounding faceted particles. As temperatures cool off again this weekend, temperature gradients could increase and drive another round of faceting. Despite the lack of new snow, the blessing of low-angle sun this time of year is that the snow holds up for long periods.

recent observations

I found the deepest snow of my travels this season today on the north facing slopes of the Knob, the outcrop of weathered granite north of Red’s Lake. A convex roll held 80 cm (31 in) of soft, facets, rounded forms and a 10 cm (4”) layer of fist hardness depth hoar on the ground.

Climbing up the south slopes, damp surface snow with cooler snow below clogged climbing skins similar to what happens in the spring.  The snow surface texture changed every few feet, from wind blasted hard slab, soft settled dry snow, to wet clogging snow. A thin, crumbly sun crust marked the interface between the snow prior to the wind event of the first of year and a few inches of snow that managed to stay on the snow surface.

Near surface faceted snow was found wherever the snow was dry. Despite air temperatures above freezing, low January sun angles and long, clear, relatively cold nights keep the sun’s energy from melting the snow surface on north aspects in open glades.

Snow pit tests did not reveal any reactive weak layers. The depth hoar layer, unlike last year at this time, did not collapse.






weather summary

The ridge of steel continues to control the dry, mild early January weather. Overnight lows at the 9,000 ft. level are in the upper 20’s and low 30’s this morning. Today will be a few degrees cooler with highs at the 9,000 ft elevations in the mid to upper 40’s- a big difference from the upper 50’s of a few days ago. Ridgetop winds will be light and variable today. A cooling trend will continue through the weekend and into the first past of next week.

Clouds, cooler temperatures and slight chance of snow on Sunday are the only changes to the forecast. An atmospheric river event is forecasted to hit the Pacific Northwest next weekend; the question is how far south this potential snow maker will come.

Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 15 mph
Maximum wind gust in the last 24 hours: 26 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 0 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Friday Friday Night Saturday
Weather: partly sunny partly cloudy partly cloudy
Temperatures: 46 deg. F. 31 deg. F. 40 deg. F.
Mid Slope Winds: NE NE NW
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: partly cloudy cloudy mostly cloudy
Temperatures: 41 deg. F. 25 deg. F. 35 deg. F.
Ridge Top Winds: N NE NE
Expected snowfall: 0 in. 0 in. 0 in.
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