THIS AVALANCHE FORECAST EXPIRED ON April 17, 2020 @ 6:56 am
Avalanche Forecast published on April 16, 2020 @ 6:56 am
Issued by Steve Reynaud - Tahoe National Forest

Sunny and warm conditions are expected today with the chance of showers and thunderstorms this afternoon.  Loose wet and wet slab avalanche problems will continue to be a concern.  MODERATE avalanche danger will exist as rapid daytime warming occurs.

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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Cooler air temperatures overnight will allow for a better refreeze of the snow surface than yesterday.  Full sun this morning with rapid warming will again allow the snow surface crust to melt and become wet and punchy into the mid-day.  Loose wet avalanches will become possible on all aspects and elevations as the snow surface becomes wet and loses strength.  Any rain showers this afternoon could increase loose wet activity.  Avalanches large enough to injure or bury a backcountry user are possible today.

Avoid steep terrain in areas where the surface crust is no longer supportable.  E-SE-S aspects will melt the quickest, followed by varied rates on SW-W-NW-N-NE aspects.   Timing will be important before snow conditions deteriorate. 

Avalanche Problem 2: Wet Slab
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The March 24 buried surface hoar layer is 1 to 2 feet below the snow surface on open NW-N-NE-E aspects at all elevations.  This snowpack structure along with our current weather conditions could allow for wet slab avalanches to occur as meltwater percolates down to the buried surface hoar layer.  A large natural wet slab avalanche occurred in Desolation Wilderness on Sunday.  These wet slab avalanches are notoriously difficult to forecast with a high degree of uncertainty.

Timing and terrain choices can help to limit exposure to these wet slab avalanches.  Get an early start!  Avoid deep wet snow and steep terrain later in the day as the snowpack loses supportability.  



recent observations
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A large natural wet slab avalanche was reported from Desolation Wilderness, thought to have occurred sometime on Sunday.  This avalanche was on a NE aspect, mid-slope, with wide propagation.  It occurred off of the ridge between Pyramid Peak and Mt. Price.

Observations from Mt. Tallac showed a poor overnight refreeze.  Soft snow conditions existed by mid-morning on areas with direct sun.  By 11:30am, mostly wet snow existed at all elevations with some occasional firm snow in shaded locations.  Monitoring the March 24 buried surface layer showed that this layer has been thoroughly wetted and did not respond to snowpack tests. 

Red Lake Peak on Carson Pass showed a good overnight refreeze of the upper snowpack.  Strong melt freeze crusts up to 8'' thick provided good travel conditions in the mid-morning hours.

Weather and CURRENT CONDITIONS
weather summary

Cooler air has moved into our region with unsettled weather expected through the weekend.  Overnight temperatures were near or slightly above freezing along the Sierra Crest, cooler than the previous night.  Winds have shifted to the NE, and are forecasted to remain light with some moderate gusts at the upper elevations.  Temperatures today will be near seasonal norms, but cooler than yesterday.  Full sun this morning with increasing clouds today and Friday could bring some light showers and potential thunderstorms in the afternoon hours.  Snow levels are expected to be around 8000' with little accumulation.  Additional chances for precipitation remain for the weekend and on Sunday night into Monday. 

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 28 to 37 deg. F.
Max. temperature: 43 to 54 deg. F.
Average ridgetop wind direction: NW shifting to NE
Average ridgetop wind speed: 15 to 25 mph
Maximum ridgetop wind gust: 48 mph
New snowfall: 0 inches
Total snow depth: 57 to 78 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Thursday Thursday Night Friday
Weather: Partly cloudy. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 10%. Partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 10%. Mostly cloudy. Scattered showers and slight chance of thunderstorms in the afternoon. Snow levels below 7000 feet increasing to 7000 feet in the afternoon. Chance of precipitation is 35%.
Temperatures: 42 to 50. deg. F. 30 to 34. deg. F. 41 to 50. deg. F.
Mid Slope Winds: Light winds. East 5 to 15 mph. East winds up to 10 mph.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. up to 1 inch. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Thursday Thursday Night Friday
Weather: Partly cloudy. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 10%. Mostly cloudy then becoming partly cloudy. Snow levels below 7000 feet. Chance of precipitation is 10%. Mostly cloudy. Scattered showers and slight chance of thunderstorms in the afternoon. Snow levels below 7000 feet increasing to 7500 feet in the afternoon. Chance of precipitation is 40%.
Temperatures: 35 to 42. deg. F. 26 to 30. deg. F. 35 to 41. deg. F.
Ridge Top Winds: East 10 to 15 mph. Gusts up to 25 mph in the morning. East around 15 mph with gusts to 30 mph. East around 15 mph with gusts to 25 mph in the morning becoming light.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. up to 1 inch. | 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