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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April 6, 2013 at 6:43 am |
Avalanche danger is LOW for all elevations and aspects. Very isolated pockets of wind slab exist in recently wind loaded areas above treeline. Normal caution is advised. |
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Cloud cover increased over the forecast area last night ahead of a low pressure system that is expected to move through the forecast area Sunday night and Monday. For today expect mostly cloudy skies and moderate speed southwest winds. Remote sensors are reporting air temperatures this morning in the mid 20s to low 30s for areas above 8,000'. Maximum daytime air temperatures are forecast to reach into the mid 30s to upper 40s today for areas above 7,000'. Ridgetop winds remain out of the southwest this morning at moderate speed. Wind speed is forecast to begin increasing tonight ahead of the approaching low pressure system.
Observations made yesterday on Round Top Peak (Carson Pass area) revealed surface cold snow conditions with very little new snow, but pockets of wind loading up to 1 foot deep on northerly aspects. Layers of rimed snow crystals were observed within the wind loaded snow, creating a weak layer below the surface wind slab. Minimal cracking was observed from skier weight on these wind slabs. Formal snowpit tests yielded mixed results on propagation potential showing possible propagation with a low likelihood of triggering (videos, more info).
Below the colder snow at the surface, a thick layer of wet snow on all aspects remains in a slow state of refreezing after the recent rain and warm air temperature snowpack melt that has occurred over the past 2 weeks. Free water drainage from this layer is well established with continued slow refreezing expected over the next several nights.
Avalanche Problem #1: Wind Slabs
Very isolated pockets of wind slab exist above treeline in recently wind loaded areas. There remains a low likelihood of human triggered wind slabs today. Slab depth up to 1 foot thick has been observed in some areas. Complex or extreme terrain and unsupported slopes above cliff bands on northerly aspects are the most likely place for a human triggered avalanche to occur today. While these slabs are relatively shallow, secondary terrain features such as rocks, trees, and terrain traps could greatly magnify the consequences of becoming caught in a relatively small slab avalanche today.
Cloud cover throughout the day, convective snow surface cooling from moderate speed SW winds, and well established free water drainage from the snowpack are expected to keep significant amounts of surface wet snow instability from forming today.
Avalanche danger is LOW for all elevations and aspects. Very isolated pockets of wind slab exist in recently wind loaded areas above treeline. Normal caution is advised.
0600 temperature: | 23 to 31 deg. F. |
Max. temperature in the last 24 hours: | 32 to 39 deg. F. |
Average wind direction during the last 24 hours: | Southwest |
Average wind speed during the last 24 hours: | 32 mph |
Maximum wind gust in the last 24 hours: | 48 mph |
New snowfall in the last 24 hours: | O inches |
Total snow depth: | 45 to 83 inches |
For 7000-8000 ft: |
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Saturday: | Saturday Night: | Sunday: | |
Weather: | Mostly cloudy skies. | Mostly cloudy skies. | Mostly cloudy skies with a slight chance of snow showers. A chance of snow showers in the afternoon. |
Temperatures: | 41 to 48 deg. F. | 26 to 33 deg. F. | 38 to 45 deg. F. |
Wind direction: | SW | SW | SW |
Wind speed: | 15 to 20 mph with gusts to 35 mph. | 15 to 20 mph with gusts to 30 mph, increasing to 25 to 30 mph with gusts to 40 mph after midnight. | 25 to 40 mph with gusts to 60 mph. |
Expected snowfall: | O in. | O in. | 0 to trace in. |
For 8000-9000 ft: |
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Saturday: | Saturday Night: | Sunday: | |
Weather: | Mostly cloudy skies. | Mostly cloudy skies. | Mostly cloudy skies with a slight chance of snow showers. A chance of snow showers in the afternoon. |
Temperatures: | 34 to 41 deg. F. | 25 to 32 deg. F. | 30 to 38 deg. F. |
Wind direction: | SW | SW | W |
Wind speed: | 20 to 30 mph with gusts to 45 mph. | 25 to 35 mph with gusts to 50 mph, increasing to 30 to 40 mph with gusts to 60 mph after midnight. | 50 to 60 mph with gusts to 90 mph. |
Expected snowfall: | O in. | O in. | 0 to trace in. |
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