The last avalanche forecast for the 2023-2024 season posted on April 21st. Thank you to all who contributed to the avalanche center this season through observations, volunteer time, and/or financial contributions.
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The last avalanche forecast for the 2023-2024 season posted on April 21st. Thank you to all who contributed to the avalanche center this season through observations, volunteer time, and/or financial contributions.
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November 20, 2012 at 7:45 am |
Near and above treeline, very isolated pockets of MODERATE avalanche danger exist on NW-N-NE aspects on slope 35 degrees and steeper. For all other areas, avalanche danger is LOW. |
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Winds are increasing significantly this morning across the forecast area ahead of another warm storm system that will bring light precipitation to the forecast area late this afternoon into Wednesday. Gale force southwest ridgetop winds will continue to increase today with gusts 85 to 100 mph forecast for this afternoon and tomorrow. Most of the rain and snow associated with this weather system will remain west of the Sierra Crest with nearly all of the spill over remaining west of Highway 89. Snow level will remain between 7,000' and 8,000' for the majority of the event before falling to near 6,500' at the tail end of precipitation. Air temperatures will warm today, especially for areas below 8,000' with low to upper 40s expected. Mid 30s to low 40s are forecast today for areas above 8,000'.
Observations made yesterday in the Carson Pass area and Mount Rose area continued to show ongoing instability within the snowpack. On Carson Pass, widespread wind slabs were observed in wind loaded areas around Frog Lake, Elephant's Back, and above Red Lake. These wind slabs continued to fail on storm snow instabilities within the recent storm snow. In most areas the wind slabs are strong enough to hold in place and prevent snowpack failure. In areas where the slab is less than 1 foot thick, small skier triggered wind slab releases occurred in response to intentional triggering (photo, videos, more info).
In the Mount Rose area of the Carson Range, snowpit data collected on Tamarack Peak continued to show weak basal facets at the base of the most recent storm snow on N to NE aspects mainly above 9,500'. The recent storm snow is now a very cohesive slab on top of this facet layer. In snowpit tests, this facet layer collapsed easily and propagated cleanly (pit profile, video). This layer appears weakest on slopes that received little to no traffic prior to the most recent snowfall.
Today's Primary Avalanche Concern: Wind Slabs
Isolated areas of lingering storm snow instability exist at the base of recently formed wind slabs. Natural avalanches are unlikely. Human triggered avalanches will remain possible. Wind slabs are expected to be stubborn and hard to trigger today. Few clues to instability will be apparent outside of the snowpit.
Today's Secondary Avalanche Concern: Persistent Slabs
This concern has only been observed in the Mount Rose area where a layer of weak basal facets exists below the recent storm snow. The facet layer is most well developed on N to NE aspects above 9,500'. Natural avalanches are unlikely. Human triggered avalanches are possible.
Near and above treeline, very isolated pockets of MODERATE avalanche danger exist on NW-N-NE aspects on slope 35 degrees and steeper. For all other areas, avalanche danger is LOW.
0600 temperature: | 24 to 34 deg. F. |
Max. temperature in the last 24 hours: | 31 to 37 deg. F. |
Average wind direction during the last 24 hours: | Southwest |
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: | O inches |
Total snow depth: | 15 to 34 inches |
For 7000-8000 ft: |
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Tuesday: | Tuesday Night: | Wednesday: | |
Weather: | Cloudy skies with isolated snow showers in the afternoon, mainly west of Hwy 89. | Cloudy skies with rain and snow likely west of Hwy 89. Otherwise scattered showers. | Cloudy skies becoming mostly cloudy. Scattered snow showers in the morning decreasing to isolated showers in the afternoon. |
Temperatures: | 41 to 48 deg. F. | 29 to 34 deg. F. | 33 to 39 deg. F. |
Wind direction: | SW | SW | SW |
Wind speed: | 15 to 30 mph with gusts to 45 mph, increasing to 30 to 45 mph with gusts to 65 mph. | 30 to 45 mph with gusts to 70 mph. | 40 to 45 mph with gusts to 70 mph, decreasing to 30 to 35 mph with gusts to 50 mph in the afternoon. |
Expected snowfall: | 0 to trace in. | West of Hwy 89, up to 4 in. | West of Hwy 89, up to 1 in. |
For 8000-9000 ft: |
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Tuesday: | Tuesday Night: | Wednesday: | |
Weather: | Cloudy skies with isolated snow showers in the afternoon, mainly west of Hwy 89. | Cloudy skies with rain and snow likely west of Hwy 89. Otherwise scattered showers. | Cloudy skies becoming mostly cloudy. Scattered snow showers in the morning decreasing to isolated showers in the afternoon. |
Temperatures: | 34 to 42 deg. F. | 28 to 33 deg. F. | 30 to 35 deg. F. |
Wind direction: | SW | SW | SW |
Wind speed: | 40 to 45 mph with gusts to 75 mph, increasing to 55 to 60 mph with gusts to 85 mph in the afternoon. | 50 to 55 mph with gusts to 85 mph, increasing to 60 to 65 mph with gusts to 95 mph after midnight. | 55 to 65 mph with gusts to 100 mph. |
Expected snowfall: | 0 to trace in. | West of Hwy 89, up to 4 in. | West of Hwy 89, up to 1 in. |
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