Mammoth Basin Snowpack Summary - 2015-01-28 07:00

Avalanche Advisory published on January 28, 2015 @ 7:00 am
Issued by Sue Burak - Inyo National Forest
Snowpack Discussion

Yesterday’s light snow accumulations and light winds took a visual edge off the old skin tracks, sand descent tracks in the upper Lakes Basin but there was not enough new snow to form slabs. Along exposed ridges above Lk George, there were a few areas where the wind blew snow into little 5” drifts. The weekend’s sun, mild daytime highs and mild nights created moist faceted snow on north facing slopes above 9,000 ft. capped by a thin melt freeze crust. East and west facing slopes had thick melt freeze crusts and underneath, moist facets and rounds. Until last weekend, there were many areas where good settled powder, aka near surface facets, were found in north facing sheltered areas despite it being about 4 weeks since the last storm. After this latest round of warm temperatures, mild nights and increasing sun angles, you can really see the power of the sun as south aspects are corn snow or slopes have lost their snow.

The January temperature roller coaster- highest daytime temperature was 60 on January 6. There were 9 days in January when the daytime high temperature was 50 F or higher. Last year, there were 11 days when the high was 50 F or higher. The average daily temperature this month was 32 F and last year it was 34 F. January 2014 and 2015 are very similar except this year’s skimpy snowpack has more water content than last year.  Let’s hope that, just like last year, the storms start coming in February and March.

recent observations

Low clouds, temperatures around 30 F and slight northeast breezes protected the inch of new snow from warming today above 9,000 ft. Thick melt freeze crusts dominated the snow surface on all aspects. Sheltered north facing trees and near treeline slopes had a thin melt freeze crust covered by an inch of new snow. Areas that harbored near surface facets and soft snow had thin melt freeze crusts and moist facets below the crusts.  Snowpit data showed a decrease in temperature gradients from last week and rounding facets and clusters of faceted forms. Snowpit tests showed the melt freeze layer breaking up as the column is isolated but no instabilities were seen in extended column and compression tests.

CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 28 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 30 mph
Maximum wind gust in the last 24 hours: 50 mph
New snowfall in the last 24 hours: 1 inches
Total snow depth: 19 inches

The tropical moisture surge moved east last night, leaving moisture at the mid-levels that produces cloudy skies and cool temperatures today. The storm-killing Rex Block moves in today. The entire western United States is high and dry for the next week to 10 days.

Daytime highs reach the mid 30’s today. Cloudy skies will act to keep temperatures in the mid to upper 30’s for the rest of the week. Night time lows will be mild; around 30 F. Temperatures will be in the mid to upper 30’s for the rest of the week

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Wednesday Wednesday Night Thursday
Weather: clouds and sun mostly cloudy slight chance of snow
Temperatures: 35 deg. F. 29 deg. F. 36 deg. F.
Wind direction: NE E NE
Wind speed: 5 5 5
Expected snowfall: 0 in. 0 in. t in.
Over 10,000 ft.
  Wednesday Wednesday Night Thursday
Weather: clouds and sun cloudy slight chance of snow
Temperatures: 26 deg. F. 23 deg. F. 26 deg. F.
Wind direction: E E NE
Wind speed: 5 5 5
Expected snowfall: 0 in. 0 in. t in.

This snowpack summary applies only to backcountry areas outside established ski area boundaries. This snowpack summary only describes general avalanche conditions and local variations always occur. This snowpack summary expires 24 hours after the posted time unless otherwise noted. The information in this snowpack summary is provided by the USDA Forest Service who is solely responsible for its content.

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