THIS AVALANCHE FORECAST EXPIRED ON April 27, 2020 @ 6:51 am
Avalanche Forecast published on April 26, 2020 @ 6:51 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

Last night's refreeze won't last long in today's sunny warm weather. Once it melts, avalanches of loose wet snow and cornice failures will be possible. MODERATE avalanche danger will quickly form at all elevations today.

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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A thin refreeze may have occurred during the night after the cloud cover dissipated since the snowpack could radiate heat out into the clear night sky. Today's warm weather and strong sunshine will quickly melt through the thin refrozen surface and expose deep wet snow. The E-SE-S aspects should melt first followed by all other aspects as the day warms up. 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 especially on large steep slopes or in areas where terrain traps exist. 

Recreating on on lower angle terrain without steep slopes above once the snow becomes soft and wet represents one way to avoid loose wet avalanche problems. Starting early to try and catch the short window of supportable snow and finishing before the snow becomes deep and wet is another. 

Avalanche Problem 2: Cornice
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Warm sunny weather will continue to weaken the cornices that exist along many ridgelines. 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 when they impact the slopes below them.

Cornices often break farther back from their edges than expected or at unexpected times. Staying far away from the edges of cornices and not traveling 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 on Donner Peak and Mt. Judah (Donner Summit area) found little to no evidence of an overnight refreeze. Barely supportable or unsupportable deep wet snow existed on E aspects by 8:30 with W and NW aspects following suit by 10:00 am. Ski cuts on steep E facing test slopes did cause some small loose wet sluffs yesterday around 10:00 am.  

* Debris from recent cornice collapses and loose wet avalanches that likely occurred on 4/23 or 4/24 existed on Mt. Judah (Donner Summit area). 

Weather and CURRENT CONDITIONS
weather summary

Cloud cover started to clear around 2 am but overnight temperatures remained well above freezing in most places with the warmest temperatures at upper elevations. The inversion should lift quickly today. Expect sunny skies and warmer than normal weather. Tomorrow a weak system passing north of the area may push a few clouds into the area. The SW winds should also continue through 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: 37 to 45 deg. F.
Max. temperature: 49 to 59 deg. F.
Average ridgetop wind direction: SW
Average ridgetop wind speed: 15 to 20 mph
Maximum ridgetop wind gust: 36 mph
New snowfall: 0 inches
Total snow depth: 43 to 69 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Sunny. Snow levels 9000 feet. Chance of precipitation is 0%. Clear. Snow levels 9000 feet decreasing to 7500 feet after midnight. Chance of precipitation is 0%. Partly cloudy. Snow levels 7500 feet increasing to 10000 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 57 to 63 deg. F. 34 to 39 deg. F. 59 to 65 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.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Sunny. Snow levels 9000 feet. Chance of precipitation is 0%. Clear. Snow levels 9000 feet decreasing to 7500 feet after midnight. Chance of precipitation is 0%. Partly cloudy. Snow levels 7500 feet increasing to 10000 feet in the afternoon. Chance of precipitation is 0%.
Temperatures: 50 to 56 deg. F. 31 to 36 deg. F. 53 to 59 deg. F.
Ridge Top Winds: Southwest 15 to 25 mph with gusts to 40 mph. Southwest 15 to 25 mph with gusts to 45 mph. Southwest around 15 mph with gusts to 30 mph in the morning becoming light.
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