THIS AVALANCHE ADVISORY EXPIRED ON March 21, 2017 @ 6:44 am
Avalanche Advisory published on March 20, 2017 @ 6:44 am
Issued by Steve Reynaud - Tahoe National Forest

In below treeline terrain, Low avalanche danger will quickly rise to Moderate avalanche danger as daytime warming occurs and loose wet avalanche activity becomes possible.  Low avalanche danger will exist in near and above treeline terrain through the day.  Avoid traveling in areas below large cornices and glide cracks.  Avalanche danger is expected to rise tonight and tomorrow as the next incoming storm impacts our area.

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.

2. Moderate

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Below Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
    Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
Avalanche Problem 1: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Another similar day is expected with a marginal refreeze overnight, partly cloudy conditions and moderate to strong SW winds.  As daytime warming occurs, loose wet avalanches will become possible in below treeline terrain, wind protected areas, and slopes below around 8000' on all aspects.  Open areas above 8000' are expected to have a better overnight refreeze of the snow surface.  Increasing SW winds should also delay snow surface melt in wind exposed areas. 

If the snow becomes wet and unsupportable in your area, it's time to change aspects to where colder snow exists.  Terrain traps, such as gullies, can magnify the consequences of even small loose wet activity.  Avoid traveling below large cornices and glide cracks.

recent observations

Observations were made and received from Genoa Peak (East Shore area), Negro Canyon (Donner Summit area), and Stevens Peak (Carson Pass area).  Generally warmer conditions with less cloud cover through our area than forecasted leading to more solar radiation and wet snow.  SE/S aspects above 8000' on Stevens Peak had a good snow surface refreeze with corn snow conditions through the midday.  Strong SW winds in this area were delaying snow surface melt.  Wind protected areas, below treeline terrain, and terrain below 8000', all showed poor refreeze conditions with wet and unsupportable snow starting in the late morning hours.  Small skier triggered loose wet activity occurred at Negro Canyon and Stevens Peak.

Weather and CURRENT CONDITIONS
weather summary

Partly cloudy skies this morning before increasing clouds develop ahead of the incoming storm tonight.  SW winds will pick up this afternoon with ridge gusts up to 80mph.  The next storm begins tonight and will last through Wednesday.  Total QPF has been downgraded to 1-1.5'' along the Sierra Crest as this storm begins to split.  Uncertainty exists as to snow amounts and snow levels at this point.  8-16'' of snow is possible above 7500-8000' and snow levels could drop Tuesday night into Wednesday morning as colder air moves into the area.  Additional storms are forecasted for Friday and for Sunday with a progressively cooling trend into the next week.

 

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 32 to 41 deg. F.
Max. temperature in the last 24 hours: 47 to 51 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 30 to 40 mph
Maximum wind gust in the last 24 hours: 64 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 115 to 168 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Slight chance of showers. Cloudy. Chance of showers in the evening, then showers likely after midnight. Cloudy. Showers through the day. Slight chance of thunderstorms through the day.
Temperatures: 47 to 53 deg. F. 32 to 37 deg. F. 35 to 42 deg. F.
Wind Direction: S SW S
Wind Speed: 15 to 25mph with gusts to 55mph. 15 to 25mph. Gusts up to 45mph increasing to 60mph after midnight. 20 to 30mph with gusts to 40mph.
Expected snowfall: 0 in. Trace in. Up to 2 in.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Mostly cloudy. Cloudy. Chance of showers in the evening, then showers likely after midnight. Cloudy. Snow showers in the morning, then snow showers and slight chance of thunderstorms in the afternoon.
Temperatures: 41 to 49 deg. F. 31 to 37 deg. F. 28 to 35 deg. F.
Wind Direction: S SW SW
Wind Speed: 30 to 40mph with gusts to 70mph. 30 to 40mph with gusts to 80mph. 30 to 50mph with gusts to 80mph.
Expected snowfall: 0 in. Up to 2 in. 2 to 8 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.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258