THIS AVALANCHE FORECAST EXPIRED ON April 28, 2020 @ 7:00 am
Avalanche Forecast published on April 27, 2020 @ 7:00 am
Issued by Andy Anderson - Tahoe National Forest - Sierra Avalanche Center

Warm sunny weather today will make short work of last night's refreeze and avalanches of loose wet snow will be possible as soon as the surface crust melts. Cornice failures also remain possible today. MODERATE avalanche danger will quickly form at all elevations.

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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Despite the warm overnight temperatures, a thin refrozen surface crust should have formed during the night under mostly clear skies. Strong April sun and warm weather will quickly melt through this crust 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. 

Loose wet avalanche on Jobs Peak from 4/25 or 4/26

Photo: Loose wet avalanche on Jobs that likely occurred on 4/25 or 4/26.

Avalanche Problem 2: Cornice
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Cornices that exist along many ridgelines will continue to weaken in today's warm sunny weather. Large pieces could break off of these overhanging waves of snow as they melt. These blocks of snow could injure a person on their own and may entrain more wet snow 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.

Photo: Large cornices looming above a slope on 4/26.

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

* Observers reported a decent refreeze above 8000 ft yesterday on Jobs Peak (south of Heavenly) and in the Forestdale Divide area (near Carson Pass). In these areas, the snow remained supportable until ~11 am on sunny slopes. On Rubicon Peak (West Shore) less refreeze had occurred and the snow was barely supportable by 10:30 am on E aspects. Below 8000 ft unsupportable punchy wet snow existed in all of these areas by 11 am. 

* A snowmobile brake check on a steep slope with buried rocks in the Forestdale Divide area (near Carson Pass) resulted in a small wet loose pile that ran downhill about 100ft around noon yesterday.

* Debris from recent loose wet avalanches that likely occurred on 4/25 or 4/26 existed in the NE gully of Jobs Peak (South of Heavenly). 

Weather and CURRENT CONDITIONS
weather summary

While the night was mostly clear a few clouds did move through the region during the overnight hours. A weak system passing by the forecast area should allow the SW winds to continue today and thin clouds in a few places (mostly N of Hwy 50) today. Temperatures should remain well above normal. By tomorrow temperatures should climb even more and any remaining cloud cover should depart. Expect the warmest day of the year so far tomorrow with daytime highs forecasted to climb into the upper 60's to low 70's between 7000 and 8000 ft and low 60's above 8000 ft.  

CONDITIONS ALONG THE SIERRA CREST BETWEEN 8200 FT. AND 9200 FT. IN THE LAST 24 HOURS
Weather Station Map
Weather Station Table
6am temperature: 35 to 44 deg. F.
Max. temperature: 46 to 56 deg. F.
Average ridgetop wind direction: SW
Average ridgetop wind speed: 20 mph
Maximum ridgetop wind gust: 45 mph
New snowfall: 0 inches
Total snow depth: 41 to 68 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy. Snow levels 8000 feet increasing to 10500 feet in the afternoon. Chance of precipitation is 5%. Partly cloudy then becoming clear. Snow levels 11500 feet. Chance of precipitation is 0%. Sunny. Snow levels 12000 feet. Chance of precipitation is 0%.
Temperatures: 59 to 65 deg. F. 37 to 42 deg. F. 65 to 71 deg. F.
Mid Slope Winds: West winds around 10 mph increasing to west 10 to 15 mph in the afternoon. West winds 10 to 15 mph with gusts to 25 mph in the evening then becoming light. Light winds.
Expected snowfall: No accumulation. | SWE = none. No accumulation. | SWE = none. No accumulation. | SWE = none.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy. Snow levels 8000 feet increasing to 10500 feet in the afternoon. Chance of precipitation is 5%. Partly cloudy then becoming clear. Snow levels 11500 feet. Chance of precipitation is 0%. Sunny. Snow levels 12000 feet. Chance of precipitation is 0%.
Temperatures: 53 to 59 deg. F. 35 to 40 deg. F. 58 to 64 deg. F.
Ridge Top Winds: West around 15 mph with gusts to 25 mph. West around 15 mph with gusts to 30 mph in the evening becoming light. Light winds.
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