Eastern Sierra Avalanche Forecast - 1/5/14

Avalanche Advisory published on January 5, 2014 @ 7:08 am
Issued by Sue Burak - Inyo National Forest

There is not enough snow to issue advisories at this time. Read on to learn about snowpack conditions in our area.

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advisory discussion

Mild January days, cold clear nights and a shallow snow cover continue to stoke th facet machine. North facing slopes at mid-elevations in Rock Creek, Mammoth and the White Wing area are holding the 8-14 inches of snow wells but depths are so shallow, hittig rocks is a certainty. We visited the White Wing area and found about 18" on an open east-southeast facing slope.  While many SE and E slopes are bare, this area may have been wind loaded from the north winds that stripped the Red Cone bowl as couple of weeks ago. Shaded NE facing slopes below treeline had less snowdepth and the snow lacked any cohesion- sugar snow.

As expected, the snowpack was faceted top to bottom with a 1 cm sun crust on the surface.  Densities were higher and the snow was slab-like compared to the sugar textured snow found elsewhere in the area.  There was a prominent low density layer of large facets 10 -11 inches down (see photo). A crack formed from collapse of the weak layer during compression tests but the block did not slide off the column. ECT’s tests showed collapse but no propagation. Compression tests are an effective test for crack initiation but do not provide any information on crack propagation; after all, we want information on whether a slope will avalanche on a weak layer.

Pit on ESE facing slope, 9,400 ft., 28 degrees. Low density layer is prominent at 10-11” down from the surface. There is a thin icy sun crust on top of the fist hardness facets. This layer represents the inch or two of snow that fell in mid-December. The slab on top is snow that fell from December 20-22- the higher density of this layer is the result of wind. CTM18,19 Q2 x4. ECTN18,21,22.

With a significant snow load, this weak layer could become more reactive and form a persistent weak layer. A few inches of new snow will only add another weak layer to the thin snowpack.

recent observations

Quiet and dry weather is expected through Monday. Temperatures will be mild today with highs in the mid 40’s to 50 degrees.  Higher elevations will be a little cooler with highs around 40 F. Night time lows continue to be in the low 20’s and upper teens.

Northeast winds will increase over the ridgetops this afternoon and Monday as the first of three weak systems track north of our area. The high elevations could pick up a few inches of snow on Tuesday afternoon and Wednesday.  Long range outlooks show a weak storm for the weekend followed by the ridge building back in for a clear week the second week of January.  

Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 26 deg. F.
Max. temperature in the last 24 hours: 49 deg. F.
Average wind direction during the last 24 hours: NE
Average wind speed during the last 24 hours: 40 mph
Maximum wind gust in the last 24 hours: 56 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 15 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Sunday Sunday Night Monday
Weather: sunny clear mostly sunny
Temperatures: 45 deg. F. 28 deg. F. 22 deg. F.
Mid Slope Winds: SE W SW
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
Sunday Sunday Night Monday
Weather: clear clouds mostly sunny
Temperatures: 45 deg. F. 26 deg. F. 44 deg. F.
Ridge Top Winds: NE E SW
Expected snowfall: 0 in. 0 in. 0 in.

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