This Avalanche Advisory was published on December 10, 2012:
December 10, 2012 at 8:01 am | |
The avalanche danger remains LOW for all elevations and aspects. Continue to use normal caution when traveling in the backcountry. Icy slopes pose the greatest hazard by making long sliding falls that are difficult to control or arrest a real possibility today. |
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Forecast Discussion:
An inversion exists over the forecast area this morning with remote sensors showing temperatures in the high 20's below 7000 ft. and in the mountain valleys. Above 7000 ft. temperatures have warmed up some overnight, and remote sensors indicate temps in the mid 30's. The high pressure ridge should remain over the forecast area through tomorrow, and the northeasterly winds should start to decrease today and tonight. These two things will combine to allow more warming to occur over the next 24 hours. The forecast calls for today's highs to climb about 5 degrees higher than yesterday's and for tomorrow's highs to climb another 4-8 degrees. By tomorrow afternoon the winds should shift to the southwest and increase ahead of an approaching low pressure.
Yesterday on Lincoln Ridge (near Yuba Pass) and on Relay Peak (Mt. Rose backcountry) the snow surface consisted of a frozen rain crust at all elevations (photos from Lincoln Ridge and Relay Peak). This crust remains thick and supportable below 9200 ft and becomes more variable at the upper elevations. Below and on top of this surface crust a small layer of weak sugary snow has formed in many areas (snowpit from Lincoln Ridge, snowpit from Relay Peak). Below these facets another much thicker and stronger layer of frozen snow exists.
Avalanche Concerns:
Weak December sunshine and relatively cool daytime highs should not create enough melting for significant wet snow avalanche conditions to form today. Some softening may occur on the sun-exposed southerly aspects today due to daytime warming. Even though avalanche activity remains unlikely today the icy snow surface creates another potentially serious hazard. Falls on this kind of snowpack become much more likely and much more difficult to control or arrest. The ongoing faceting taking place between the top two rain crusts in the snowpack will be something to keep an eye on as future loading occurs.
The bottom line:
The avalanche danger remains LOW for all elevations and aspects. Continue to use normal caution when traveling in the backcountry. Icy slopes pose the greatest hazard by making long sliding falls that are difficult to control or arrest a real possibility today.
Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:
0600 temperature: | 33-41 deg. F. |
Max. temperature in the last 24 hours: | 34-41 deg. F. |
Average wind direction during the last 24 hours: | Northeast |
Average wind speed during the last 24 hours: | 25 mph |
Maximum wind gust in the last 24 hours: | 50 mph |
New snowfall in the last 24 hours: | O inches |
Total snow depth: | 34-46 inches |
Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS
For 7000-8000 ft: |
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Monday: | Monday Night: | Tuesday: | |
Weather: | Sunny | Clear | Sunny |
Temperatures: | 43-48 deg. F. | 35-40 deg. F. | 44-49 deg. F. |
Wind direction: | Northeast | East | Southwest in the afternoon |
Wind speed: | 10-15 mph with gusts to 25 mph | 10-15 mph becoming light after 10 pm | 0-10 mph in the morning increasing to 20-25 mph with gusts to 35 mph in the afternoon |
Expected snowfall: | O in. | O in. | O in. |
For 8000-9000 ft: |
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Monday: | Monday Night: | Tuesday: | |
Weather: | Sunny | Clear | Sunny |
Temperatures: | 37-44 deg. F. | 27-37 deg. F. | 41-47 deg. F. |
Wind direction: | Northeast | Northeast shifting to the West after midnight | West shifting to the Southwest |
Wind speed: | 15-25 mph with gusts to 40 mph | 15-20 mph with gusts to 30 mph | 10-15 mph with gusts to 25 mph increasing to 30-35 mph with gusts to 55 mph in the afternoon |
Expected snowfall: | O in. | O in. | O in. |