THIS AVALANCHE FORECAST EXPIRED ON April 26, 2020 @ 6:59 am
Avalanche Forecast published on April 25, 2020 @ 6:59 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

Warm spring weather will quickly melt through whatever refreeze occurred last night and allow avalanches of loose wet snow to become possible before midday. Cornice fall is also a possibility. MODERATE avalanche danger will form at all elevations once the surface crust melts, exposing areas of deep wet 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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Warm temperatures in most places combined with some cloud cover should have prevented much of an overnight refreeze. This morning, warm weather and strong sunshine will quickly destroy any refreeze that might have occurred exposing deep wet snow. This melting will occur on the E-SE-S aspects first and move to all other aspects during the day. The thin cloud cover forecasted for today may help spread the warming to aspects that usually receive less sun. Loose wet avalanches will become possible on steep slopes once the surface crust melts. Some of these could entrain enough snow to bury or injure a person on large steep slopes or in areas where terrain traps exist. 

Starting early to try and catch the short window of supportable snow and finishing before the snow becomes deep and wet represents one way to avoid loose wet avalanche problems. Once the snow starts getting wet and deep, it is time to avoid avalanche terrain by recreating on lower angle terrain without steep slopes above.

Avalanche Problem 2: Cornice
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Cornices will continue to weaken due to the warm weather, strong sun, and another weak overnight refreeze. Large pieces could break off of these overhanging waves of snow as they melt. These blocks of snow could injure a person or may trigger loose wet avalanches or wet slab avalanches as they impact the slopes below them.

A great deal of difficulty exists in predicting exactly where and when cornices will break. Often they break farther back from their edges than expected. Staying far away from the edge and avoiding spending any time underneath cornices can help avoid this problem. 

recent observations
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* Spring melt-freeze conditions exist on all aspects across the forecast area.

* Yesterday observations from Incline Lake Peak in the Mt. Rose Backcountry found shallow wet corn snow on supportable melt-freeze crusts before 10:00 am on SE-S aspects down to 8600 ft. By 10:45 these aspects had started to become unsupportable. Deep wet snow had formed on E before 10:45. Ski cuts on a small steep E facing test slope did trigger a small loose wet avalanche at 11:20. Wet sticky barely supportable snow existed on northerly aspects around 11 am. 

Weather and CURRENT CONDITIONS
weather summary

Some colder air settled into the valleys last night allowing colder but still above freezing overnight temperatures at lower elevations (mid 30's) and warmer temperatures (low to mid 40's) at upper elevations. A low-pressure system moving through the Pacific Northwest also pushed some high clouds into the region during the night. This cloud cover should increase today as should the SW winds. Despite the cloud cover, temperatures could climb into 60's above 7000 ft. today. The forecast calls for the cloud cover to dissipate tonight. Expect more sunny weather with warmer than normal temperatures 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: Carson Pass reported 34 deg. F and everywhere else ranged between 41 to 46 deg. F.
Max. temperature: 51 to 59 deg. F.
Average ridgetop wind direction: W
Average ridgetop wind speed: 10 mph
Maximum ridgetop wind gust: 39 mph
New snowfall: 0 inches
Total snow depth: 45 to 71 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 then becoming mostly cloudy. Snow levels 10000 feet. Chance of precipitation is 0%. Mostly cloudy then becoming clear. Snow levels 9000 feet. Chance of precipitation is 0%. Sunny. Snow levels 9000 feet. Chance of precipitation is 0%.
Temperatures: 59 to 65 deg. F. 35 to 40 deg. F. 57 to 63 deg. F.
Mid Slope Winds: Light winds becoming southwest around 15 mph with gusts to 30 mph in the afternoon. Southwest around 15 mph in the evening becoming light. Gusts up to 30 mph. Light winds becoming southwest around 15 mph with gusts to 30 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Saturday Saturday Night Sunday
Weather: Partly cloudy then becoming mostly cloudy. Snow levels 10000 feet. Chance of precipitation is 0%. Mostly cloudy then becoming clear. Snow levels 9000 feet. Chance of precipitation is 0%. Sunny. Snow levels 9000 feet. Chance of precipitation is 0%.
Temperatures: 52 to 60 deg. F. 32 to 37 deg. F. 51 to 57 deg. F.
Ridge Top Winds: Light winds becoming southwest around 15 mph with gusts to 35 mph in the afternoon. Southwest 15 to 20 mph. Gusts up to 35 mph decreasing to 25 mph after midnight. Southwest 15 to 20 mph. Gusts up to 25 mph increasing to 35 mph in the afternoon.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
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