Mammoth Basin Snowpack Summary - 2015-03-03 10:59

Avalanche Advisory published on March 3, 2015 @ 10:59 pm
Issued by Sue Burak - Inyo National Forest
Avalanche Character 1: Normal Caution
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Use normal caution when travelling in the backcountry.
Snowpack Discussion

The dry light snow that fell over the weekend has settled and continues to provide good skiing conditions. Today will be the warmest and sunniest day since the weekend storm. Snow on cold north and east facing slopes at high elevations will be spared the effects of the sun’s energy but slopes in the trees and on southerly aspects might get wet this afternoon. Look for damp snow or small rollers coming off exposed southeast slopes in the next few days. Expect to see signs of wet snow instability every day through the weekend.

Tests done yesterday were inconclusive- compression tests failed on the deeply buried weak layer of large facets but no fractures were initiated in the standard 30 loading steps. These signs of deeper weakness in the pack will be monitored several times a week. Beware that snow saws and small snow shovels can bend or break cutting the 4 to 6 inch crust.

recent observations

Loose snow sluffs were observed Monday off rocks and below cliffs in the trees below Red Cone in the Mammoth Lakes Basin. Observations made on Monday and Tuesday show new snow has settled and bonded to itself and to the underlying rain/dense snow layer formed in early February. I found patches of recrystallized snow in open glades. Expect to see more near surface faceting this week because cold clear nights and warmer days continue. If snow falls next week, these grains could become a weak layer at high elevations.

Wind slabs have a patchy distribution below ridgetops on north facing slopes. They are difficult to trigger several days after the storm. North and northeast winds stripped new snow from the entrances to many gullies and couloirs but soft dry snow is found in sheltered high elevation terrain. Reports of deeper snow in Bloody Couloir and Pika Peak noted wind affected snow with tedious booting in some places in the couloirs.


CURRENT CONDITIONS Weather Observations Between June (10,000 ft.) and Mammoth (11,000 ft.)
0600 temperature: 19 deg. F.
Max. temperature in the last 24 hours: 16 deg. F.
Average wind direction during the last 24 hours: ne
Average wind speed during the last 24 hours: 25 mph
Maximum wind gust in the last 24 hours: 38 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 26 inches

Morning lows are cold, running in the low teens but still about 5 degrees warmer than yesterday.  High elevation locations are 20 F this morning. Ridgetop winds are blowing 25 mph. Our area will see sunny and dry weather with a gradual warming trend until the end of the week. The persistent ridge builds back in and temperatures will warm to above normal by the weekend.

Daytime highs will warm a few degrees into the upper 30’s and low 40’s today at the 9,000 to 10,000 ft. elevations. High elevation temperatures will reach the mid 30’s with moderate northeast winds blowing 20 to 30 mph, gusting to 40.

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
  Tuesday Tuesday Night Wednesday
Weather: clear, sun clear clear, sunny
Temperatures: 36-42 deg. F. 11-21 deg. F. 43-49 deg. F.
Wind direction: NE NE NE
Wind speed: light light light
Expected snowfall: 0 in. 0 in. 0 in.
Over 10,000 ft.
  Tuesday Tuesday Night Wednesday
Weather: sun clear sun
Temperatures: 30-36 deg. F. 8-15 deg. F. 34-42 deg. F.
Wind direction: NE NE NE
Wind speed: 20-30 10-15 light
Expected snowfall: 0 in. 0 in. 0 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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