THIS AVALANCHE FORECAST EXPIRED ON March 10, 2018 @ 7:00 am
Avalanche Forecast published on March 9, 2018 @ 7:00 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

LOW avalanche danger exists at all elevations today. Triggering a deep slab has become unlikely on a regional scale. Unlikely does not mean impossible and a deep slab problem could still lurk on some isolated terrain features. Some isolated loose wet issues could occur today if the forecast area receives more sun or warmer temperatures than expected.

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: Deep Slab
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Triggering a deep slab avalanche has become unlikely for the vast majority of the forecast area due to the snow above the persistent weak layer becoming much stronger and the persistent weak layer adjusting to the load above it. Unlikely does NOT mean impossible and some isolated terrain features where the weak layer remains closer to the surface may still be suspect. These isolated areas could include places where a shallower overall snowpack exists or areas where trigger points like rocks, cliffy areas, single trees, stumps, etc exist on slopes with a deeper snowpack. On these isolated slopes, several tracks could exist before a person finds the trigger point that would release the entire slope. This unlikely but not impossible problem would still have severe consequences.

Even though deep slabs have become unlikely on a regional scale enough uncertainty exists concerning them that making travel plans to avoid those isolated areas where this problem could linger still represents a prudent choice. Lower angle sheltered northerly aspects continue to offer good recreation conditions.

Avalanche Problem 2: Loose Wet
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Cloud cover, winds, and slightly cooler daytime highs should keep loose wet instabilities unlikely today. Some small roller balls, pinwheels, or loose wet point releases could still become possible if the sun does come out during the day or if temperatures climb higher than expected.

recent observations
Submit Observations

* Yesterday on Mt. Lola, snowpit observations found the persistent weak layer about 1.5 m below the surface, but it had become much denser and more cohesive and no longer looked like facetted snow. Snowpit tests and observations from around the forecast area since Saturday have shown that the facet layer buried 1 to 1.5 m deep in the snowpack has become increasingly difficult to trigger. Some of the data also still indicated that if it does break the resulting fracture could still propagate along the persistent weak layer. Another loading event could still reactivate this layer.

* Some wind transport and wind-loading was observed on Castle Peak yesterday, but ski cuts and cornice cuts did not trigger any signs of instability.

* Wet sticky surface snow existed on all aspects up to 8000 ft. on Mt. Lola yesterday and up to 7800 ft. on Rubicon. Wet surface snow also existed on southerly aspects of Castle Peak by the afternoon. 

* Sheltered true north aspects above 7800-8000 ft. still held cold soft snow on Castle Peak, Rubicon, and Mt. Lola. In more exposed areas variable snow surface conditions ranging from firm wind affected snow to soft snow existed.

Weather and CURRENT CONDITIONS
weather summary

Cloud cover over the mountains last night kept temperatures near, just below, or just above freezing in most places. Two small systems should pass by the forecast area in the next 36 hours. One to the north today and one mostly to the south tomorrow. The forecast calls for an increase in cloud cover today and tomorrow and possibly some light precipitation tomorrow. Snow levels may rise to above 7000 ft. during tomorrow's event so some areas could see light rain on Saturday. For most of the forecast area only a trace to .1 inches of liquid is projected (up to 1 inch of snow above 7000 ft). In the far southern portion of the forecast area (Bear Valley and south of Carson Pass) more precipitation may accumulate.

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 32 deg. F.
Max. temperature: 37 to 44 deg. F.
Average ridgetop wind direction: Southwest
Average ridgetop wind speed: 40 mph
Maximum ridgetop wind gust: 72 mph
New snowfall: trace inches
Total snow depth: 50 to 82 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Friday Friday Night Saturday
Weather: Mostly cloudy Partly cloudy becoming mostly cloudy Mostly cloudy with a chance of rain and snow in the afternoon. Snow level starting at 6000 ft and increasing to 7000 ft. + in the afternoon.
Temperatures: 40 to 45 deg. F. 25 to 30 deg. F. 40 to 45 deg. F.
Mid Slope Winds: Southwest Southwest Variable
Wind Speed: 10 to 20 mph with gusts to 35 mph 10 to 15 mph with gusts to 30 mph Light
Expected snowfall: 0 0 trace to 1
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Mostly cloudy Partly cloudy then becoming mostly cloudy. Mostly cloudy with a chance of rain and snow in the afternoon.
Temperatures: 36 to 42 deg. F. 24 to 29 deg. F. 35 to 41 deg. F.
Ridge Top Winds: Southwest Southwest Southwest
Wind Speed: 20 to 30 mph with gusts to 60 mph decreasing to 50 mph in the afternoon 15 to 25 mph with gusts to 50 mph decreasing to 35 mph after midnight 10 to 15 mph with gusts to 30 mph
Expected snowfall: 0 0 trace to 1
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