THIS AVALANCHE FORECAST EXPIRED ON January 6, 2019 @ 6:57 am
Avalanche Forecast published on January 5, 2019 @ 6:57 am
Issued by Brandon Schwartz - Tahoe National Forest

LOW avalanche danger continues this morning for all elevations. Following the onset of snowfall, an increase to CONSIDERABLE avalanche danger will occur at all elevations this afternoon and continue through the overnight hours. Wind slab and storm slab avalanche problems will develop.

3. Considerable

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Above Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Near Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

3. Considerable

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Below Treeline
Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
    Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
Avalanche Problem 1: Wind Slab
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A wind slab avalanche problem will form quickly this afternoon following the onset of snowfall. The vast majority of wind slabs will form near treeline and above treeline on NW-N-NE-E-SE aspects and to a lesser extent in other locations including wind affected areas below treeline. Identify and travel around the edges of areas where wind drifted snow is depositing in avalanche terrain, especially near cornice features and wind pillows.

In Sierra Crest locations where weak snow and thin crusts have been observed within the top 4 to 18 inches of the existing snowpack, additional travel considerations will become warranted as this storm cycle progresses. The collapse of these weak layers below the old snow surface may allow for wind slab avalanches to take on some persistent slab characteristics, failing wider than typical, possibly wrapping around corners and across adjacent avalanche paths all at once. As these areas of higher uncertainty develop, give wind slabs a wider margin of safety than normal.

Avalanche Problem 2: Storm Slab
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A storm slab avalanche problem may form this evening and during the overnight hours as snowfall rates of 1-2" per hour create for rapid accumulation in wind protected areas. Storm slabs could form on any previously snow covered slope in below treeline or near treeline terrain.

In areas where snow surface cracking occurs while making fresh tracks either uphill or down, identify and move around the edges of avalanche terrain.

recent observations
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* Recent observations from along the Sierra Crest indicate questionable ability for the upper snowpack layers consisting of weak facets and thin crusts to support new snow loading.

* The snowpack in the Mt. Rose area (Carson Range) lacks these crusts and appears in decent condition to handle new snow loading. Shallower, weaker snow has been noted further south along the Carson Range closer to Freel and Jobs Peaks.

* Recent gale force NE wind and warming events have left behind variable snow surface conditions including firm wind packed, firm wind scoured, exposed ice, melt freeze crust, and pockets of soft unconsolidated snow. In many locations, these different conditions exist in close proximity to one another.

Weather and CURRENT CONDITIONS
weather summary

A series of storm systems is approaching the forecast area this morning. Ridgetop SW winds are increasing this morning with gusts up to 115 mph this afternoon. The onset of significant snowfall is expected to begin early this afternoon. Snowfall intensity is forecast to increase late afternoon/evening and continue through the overnight hours. The next storm system will follow quickly with another significant snowfall event Sunday evening. See NWS Reno for the latest info for today through Monday. Another storm is expected Tuesday/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: 27 to 34 deg. F.
Max. temperature: 35 to 43 deg. F.
Average ridgetop wind direction: SW
Average ridgetop wind speed: 32 mph
Maximum ridgetop wind gust: 70 mph
New snowfall: 0 inches
Total snow depth: 29 to 35 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy. Slight chance of snow in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 85%. Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 90%. Mostly cloudy. Snow likely in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 75%.
Temperatures: 31 to 36. deg. F. 22 to 27. deg. F. 26 to 31. deg. F.
Mid Slope Winds: South 15 to 30 mph increasing to 25 to 35 mph in the afternoon. Gusts up to 60 mph. Southwest 15 to 30 mph with gusts to 60 mph. Southwest 15 to 30 mph. Gusts up to 50 mph increasing to 70 mph in the afternoon.
Expected snowfall: 80% probability of 2 to 4 inches. 20% probability of 4 to 8 inches. | SWE = up to 0.40 inch. 80% probability of 6 to 12 inches. 20% probability of 12 to 18 inches. | SWE = 0.50-0.75 inch. 80% probability of 2 to 4 inches. 20% probability of 4 to 6 inches. | SWE = 0.15-0.25 inch.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Mostly cloudy. Snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 85%. Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 90%. Mostly cloudy. Snow likely in the morning, then snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 75%.
Temperatures: 27 to 32. deg. F. 19 to 25. deg. F. 22 to 27. deg. F.
Ridge Top Winds: South 40 to 60 mph. Gusts up to 95 mph increasing to 115 mph in the afternoon. Southwest 30 to 50 mph with gusts to 85 mph. Southwest 30 to 50 mph with gusts to 85 mph.
Expected snowfall: 80% probability of 3 to 6 inches. 20% probability of 6 to 10 inches. | SWE = 0.15-0.40 inch. 80% probability of 8 to 14 inches. 20% probability of 14 to 20 inches. | SWE = 0.55-0.80 inch. 80% probability of 2 to 4 inches. 20% probability of 4 to 6 inches. | SWE = up to 0.30 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