Eastern Sierra Avalanche Forecast - 1/16/15

Avalanche Advisory published on January 16, 2015 @ 7:00 am
Issued by Sue Burak - Inyo National Forest
advisory discussion

Low sun angles, seasonal temperatures and clear, dry weather are promoting near surface faceting that keeps the snow surface soft on north aspects. In places exposed to the wind, hard supportable and breakable slabs are common. These are the shortest days of the year and traditionally, back when it used to snow, this was the time of year when skiing conditions were the best. This year there are more storms than last winter but storms are moisture starved. With no storms expected to reach the area until the end of the month, and if there are no further extreme swings in temperature and winds, benign snowpack conditions should continue.  

recent observations

Yesterday’s observations on north facing slopes in the glades off the Knob, showed a variable snow surface with many areas of softer recycled powder, cavities next to rocks harboring well developed depth hoar and firm to icy wind crusts. On more sun exposed slopes, patches of soft corn had formed above soft snow and supportable wind slab. The drainage channels observed on the southwest slopes of Mammoth Mountain were not found on this north facing slope.  Continued clear days and cool clear nights on sheltered north facing slopes are favorable conditions for faceting to continue.

The snowpack on the slopes we observed was mostly pencil hardness throughout the 80 cm snowpack. The top 10 cm was near surface facets and facets at the surface and large facets at the base of the pack. Despite a snowpack composed entirely of faceted crystals, hand hardness was generally pencil with a fairly uniform slab sitting on 10 cm or so of larger faceted grains. Compression and extended column tests did not produce any results.  

weather summary

Another storm passes to the north today as strong ridging remains anchored off the Pacific Coast. Daytime highs remain in the low 40’s at the 9,000 to 10,000 ft. elevations with lows in the upper 20’s.  Higher elevation temperatures remain in the mid-30’s with lows around 24F for the rest of the week. The only variation in the weather will be some breezy conditions today and some clouds Saturday night and Sunday.

Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 23 deg. F.
Max. temperature in the last 24 hours: 32 deg. F.
Average wind direction during the last 24 hours: WSW
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: 45 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 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: mostly sunny partly cloudy mostly sunny
Temperatures: 45 deg. F. 31 deg. F. 44 deg. F.
Mid Slope Winds: SW SW SW
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Friday Friday Night Saturday
Weather: breezy partly cloudy mostly sunny
Temperatures: 33 deg. F. 27 deg. F. 35 deg. F.
Ridge Top Winds: SW NW SW
Expected snowfall: 0 in. 0 in. 0 in.
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