THIS AVALANCHE ADVISORY EXPIRED ON March 20, 2015 @ 6:51 am
Avalanche Advisory published on March 19, 2015 @ 6:51 am
Issued by Brandon Schwartz - Tahoe National Forest

Avalanche danger is LOW for all elevations and aspects. Minor loose wet instabilities are expected during the afternoon hours. Loose wet avalanches large enough to bury or injure a person are unlikely. Normal caution is advised. Sufficient snow cover for avalanche activity on SE-S-SW-W aspects exists only in isolated portions of the forecast area. Much deeper, continuous snow cover exists on NW-N-NE-E aspects.

1. Low

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Above Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Near Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

1. Low

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Below Treeline
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
    Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1: Normal Caution
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

A strong and supportable snow surface refreeze is expected to have occurred last night with near to below freezing air temperatures aided by radiational cooling under clear skies. As daytime warming progresses, areas of surface wet snow will form on sun exposed slopes. With the snowpack already subject to periods of rain and prolonged melt earlier this winter, free water drainage from the snowpack is well established. With little to no snow cover on the vast majority of SE-S-SW-W aspects, minimal instability concerns are expected on those aspects. E aspects continue to hold significant snow cover around the vast majority of the forecast area and will experience surface wet snow formation up to several inches deep by this afternoon. With free water drainage well established, wet snow instability is expected to be limited to human triggered roller balls and human triggered loose wet sluffs that require a push to set into motion in steep terrain. Loose wet avalanches large enough to bury or injure a person are unlikely today.

recent observations

Observations made yesterday on Rubicon Peak (West Shore Tahoe area) indicated that a strong overnight snow surface refreeze had occurred in the area. At 12:15 pm, the snow surface on E aspects held 0.5 to 2 inches of wet surface snow on top of ski and boot supportable melt-freeze crust from just below the summit rock tower at ~9,100' down to the transition from continuous snow cover to patchy snow cover at ~8,200. Snow cover on NW-N-NE aspects in this area is nonexistent below 7,500', patchy between 7,500' and 7,800', and continuous above 7,800'. The snow surface on NW-N-NE aspects remained firm and supportable upon departure from the area at 1 pm. No signs of wet snow instability were observed.

Across the forecast area in general, sufficient snow cover for avalanche activity on SE-S-SW-W aspects exists only in isolated areas. Much deeper, continuous snow cover exists on NW-N-NE-E aspects.

Weather and CURRENT CONDITIONS
weather summary

High pressure building over the region will bring above average air temperatures and dry weather to the forecast area today and tomorrow. Remote sensors are reporting air temperatures in the low to mid 30s this morning for areas 7,000' to 9,600'. Maximum daytime air temperatures are forecast to reach the mid 40s to upper 50s today for areas above 7,000'. Ridgetop winds are out of the east this morning and are moderate in speed. Light to moderate speed east winds are forecast to continue through today. A weak weather system will pass to the north of the forecast area Friday night. This will shift ridgetop winds to the southwest tonight and cause an increase in speed to moderate to strong for tomorrow. This passing system will also spread mid to high level cloud cover over the area tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 29 to 35 deg. F.
Max. temperature in the last 24 hours: 47 to 51 deg. F.
Average wind direction during the last 24 hours: East
Average wind speed during the last 24 hours: 23 mph
Maximum wind gust in the last 24 hours: 34 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 20 to 40 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Sunny skies. Clear skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 51 to 58 deg. F. 27 to 34 deg. F. 53 to 61 deg. F.
Wind Direction: E Variable SW
Wind Speed: 10 to 20 mph in the morning, becoming light. Light winds Light winds increasing to 15 to 20 mph with gusts to 30 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Sunny skies. Clear skies. Partly cloudy skies, becoming mostly cloudy.
Temperatures: 46 to 53 deg. F. 27 to 34 deg. F. 44 to 51 deg. F.
Wind Direction: E Variable, becoming SW after midnight. SW
Wind Speed: 15 to 20 mph with gusts to 30 mph. Light winds increasing to 10 to 15 mph with gusts to 25 mph after midnight. 10 to 15 mph with gusts to 25 mph, increasing to 30 to 35 mph with gusts to 55 mph in the afternoon.
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory covers the Central Sierra Nevada Mountains between Yuba Pass on the north and Ebbetts Pass on the south. Click here for a map of the forecast area. This advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.