THIS AVALANCHE FORECAST EXPIRED ON March 22, 2020 @ 6:56 am
Avalanche Forecast published on March 21, 2020 @ 6:56 am
Issued by Steve Reynaud - Tahoe National Forest

Loose wet avalanches will become possible today as daytime warming and increased solar radiation occur at all elevations.  A deep slab avalanche problem is unlikely, but not impossible in near and below treeline areas.  MODERATE avalanche danger continues.

2. Moderate

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Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

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Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

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
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Loose wet avalanches will become possible with increased solar radiation and daytime warming.  The potential for avalanches will start in the late morning hours and last through the afternoon.  Increasing cloud cover today could limit loose wet avalanche activity on solar aspects in some areas.  Intense March sunshine with even partly sunny skies could still make the surface snow wet and unstable.

As the surface snow becomes wet and punchy, it's time to move to different aspects.  Roller balls and pinwheels may be indicators of the potential for larger loose wet avalanches to occur.

Avalanche Problem 2: Deep Slab
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Deep slabs exist in isolated areas of the forecast region.  Weak layers of faceted snow and crusts formed during our dry February and are now buried under this recent storm snow.  A natural deep slab avalanche cycle occurred during the large storm event on last Sunday along with 2 human triggered avalanches on this weak layer, the last avalanche reported on Thursday.  Some snowpack tests continue to show that propagation is possible on this weak layer with no other signs of instabilities or other recent avalanches reported.  This avalanche problem is unlikely on a regional scale, but by no means impossible.

This deep slab avalanche problem exists on NW-N-NE aspects in near and below treeline areas.  Large triggers, steep complex terrain, or unsupported slopes may be the most likely areas for avalanche potential.  Avalanches involved with this weak layer would be large and destructive. 

recent observations
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Further investigation of the reported slab avalanche on Fireplug, in the Mt. Rose area, occurred yesterday.  It was found that this was a wind slab avalanche that failed post storm sometime on early Thursday.  This was reported to be a natural avalanche with several other similar small wind slab avalanches in the immediate area.

Reactive buried facets were found on Angora Peak (Echo Summit area) yesterday.  The facet layer was buried 3 to 4' deep in this area.  Extended column tests showed that propagation is still possible at this location.

Surface hoar has been reported in the Echo Summit, Luther Pass, Ward Canyon, Ebbetts Pass, and Donner Summit areas.  It is likely that this surface hoar will be destroyed by winds and warming temperatures ahead of the next snowfall event, but continued monitoring is warranted. 

Weather and CURRENT CONDITIONS
weather summary

Drier and warmer conditions are expected this weekend with mostly light winds.  Partly cloudy skies today with some potential for light snow mainly in the far southern part of the forecast region.  Below average temperatures and increasing winds will return next week with the potential for snow on Monday through Wednesday. 

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 17 to 26 deg. F.
Max. temperature: 24 to 35 deg. F.
Average ridgetop wind direction: NE
Average ridgetop wind speed: 10 to 25 mph
Maximum ridgetop wind gust: 45 mph
New snowfall: 0 inches
Total snow depth: 58 to 86 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Partly cloudy. Isolated snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 20%. Partly cloudy then becoming clear. Isolated snow showers in the evening. Snow levels below 7000 feet. Chance of precipitation is 15%. Sunny then becoming partly cloudy. Slight chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 20%.
Temperatures: 35 to 41. deg. F. 19 to 25. deg. F. 39 to 44. deg. F.
Mid Slope Winds: Light winds. Light winds. Light winds.
Expected snowfall: 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch. No accumulation. | SWE = trace amounts. 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy. Scattered snow showers in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 25%. Partly cloudy then becoming clear. Isolated snow showers in the evening. Snow levels below 7000 feet. Chance of precipitation is 15%. Sunny then becoming partly cloudy. Slight chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 20%.
Temperatures: 29 to 35. deg. F. 16 to 21. deg. F. 33 to 39. deg. F.
Ridge Top Winds: East around 15 mph with gusts to 25 mph. Light winds becoming east around 15 mph with gusts to 25 mph after midnight. Southeast around 15 mph with gusts to 30 mph in the morning becoming light.
Expected snowfall: 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch. No accumulation. | SWE = trace amounts. 20% probability up to 1 inch. 80% probability no accumulation. | SWE = less than 0.10 inch.
Disclaimer

This avalanche forecast is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This forecast 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 forecast applies only to backcountry areas outside established ski area boundaries. This forecast describes general avalanche conditions and local variations always occur. This forecast expires 24 hours after the posted time unless otherwise noted. The information in this forecast is provided by the USDA Forest Service who is solely responsible for its content.

For a recorded version of the avalanche forecast call (530) 587-3558 x258