THIS AVALANCHE FORECAST EXPIRED ON April 19, 2018 @ 6:56 am
Avalanche Forecast published on April 18, 2018 @ 6:56 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

MODERATE avalanche danger could exist at all elevations today due to periods of sunshine causing rapid warming of the recent snow. Any amount of April sun could cause conditions to change in a matter of minutes and allow loose wet avalanches to become possible on sun-exposed slopes. Once any signs of warming snow or wet snow exist it is time to move to colder aspects, lower angle slopes, or switch an activity that does not involve snow.

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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Below normal temperatures and mostly cloudy skies should help limit the warming that does occur today. However, short periods of intense April sunshine on the recent snow could cause enough warming for some wet snow instabilities to form. Human-triggered roller balls, pinwheels, and loose wet avalanches are possible on steep sun-exposed slopes today. Many of these loose wet instabilities should remain small, but some of them could still entrain enough snow to injure a person. They may even involve enough snow to bury a person if they occur in an area with terrain traps. Due to the high sun angles and intense sunshine, loose wet instabilities could occur on any aspect that receives any amount of sun today. If the cloud cover is as widespread and thick as forecasted, loose wet instabilities may be more limited.

Conditions can change quickly from cold soft snow to sunny warm unstable snow as soon as the sun hits the snow surface. Once the snow starts to feel wet and sticky or small signs of loose wet instabilities like small roller balls or pinwheels start to occur, it is time relocate to a colder aspect or abandon the snow for a different afternoon activity. Shaded N aspects should experience the least warming and have the best potential for preserving some cold snow.

recent observations
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* Ski cuts on steep E facing test slopes triggered ski-width-wide loose wet sluffs in the Slab Cliffs (Mt. Rose backcountry) area yesterday.

* Snow surfaces ranged from cold and dry on N aspects above 8600 ft. to warm, wet, and sticky on E-SE-S aspects and on sun-exposed areas of the NE aspects in the Slab Cliffs area yesterday.

Weather and CURRENT CONDITIONS
weather summary

Cloud cover started to increase over the region last night. The forecast calls for continued cloud cover today and increasing southwest winds as a weak low-pressure system moves across CA. This system could even bring some light snow showers to the forecast area starting this afternoon and continuing through tomorrow. By tomorrow the small storm should be on its way out of the area and the winds should shift around to the NW but remain light to moderate in speed. Temperatures should remain below average today and tomorrow. 

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 22 to 30 deg. F.
Max. temperature: 33 to 40 deg. F.
Average ridgetop wind direction: NE shifting to SSW
Average ridgetop wind speed: During the day yesterday: 5 to 10 mph | After midnight: 25 mph
Maximum ridgetop wind gust: 57 mph
New snowfall: 0 inches
Total snow depth: 50 to 95 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy with isolated snow showers in the afternoon. Mostly cloudy with scattered snow showers during the night. Mostly cloudy with scattered snow showers during the day.
Temperatures: 36 to 42 deg. F. 19 to 24 deg. F. 39 to 44 deg. F.
Mid Slope Winds: Southwest West Northwest
Wind Speed: Light in the morning increasing to 10 to 15 mph with gusts to 35 mph in the afternoon 10 to 15 mph with gusts to 30 mph in the evening becoming light overnight Light in the morning increasing to 10 to 15 mph with gusts to 25 mph in the afternoon
Expected snowfall: Trace up to 1 up to 1
For 8000 ft. to 9000 ft.
Wednesday Wednesday Night Thursday
Weather: Mostly cloudy with isolated snow showers in the afternoon. Mostly cloudy with scattered snow showers during the night. Mostly cloudy with scattered snow showers during the day.
Temperatures: 30 to 36 deg. F. 16 to 21 deg. F. 33 to 39 deg. F.
Ridge Top Winds: Southwest Southwest shifting to west after midnight Northwest
Wind Speed: 20 to 30 mph with gusts to 60 mph 20 to 30 mph with gusts to 60 mph decreasing to 10 to 15 mph with gusts to 30 mph after midnight 10 to 15 mph with gusts to 30 mph
Expected snowfall: trace up to 1 up 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