THIS AVALANCHE FORECAST EXPIRED ON April 16, 2019 @ 6:45 am
Avalanche Forecast published on April 15, 2019 @ 6:45 am
Issued by Brandon Schwartz - Tahoe National Forest

LOW avalanche danger will transition to MODERATE avalanche danger as the likelihood of loose wet and wind slab avalanche problems increase throughout the day.

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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For the second night in a row, conditions were not ideal for snow surface refreeze with cloud cover and above freezing air temperatures at about 8,200' and below. Snow surface melt rates are expected to be fairly slow today with loose wet avalanches eventually becoming a problem on all aspects and at all but the highest elevations. Avalanche size is generally expected at D1 with up to size D2 possible. How quickly this avalanche problem develops will be dependent on the strength of the surface refreeze and daytime melt rate. Rain below 7,500' may help get this avalanche problem going today.

Continuously monitor snow surface supportability and surface crust strength and thickness. When the surface crust loses supportability or melts away exposing deeper wet snow, the loose wet avalanche problem is present and it is time to exercise options to adjust terrain choices accordingly.

Avalanche Problem 2: Wind Slab
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Following the onset of new snowfall, wind slabs will become an increasing avalanche problem late today, tonight, and into tomorrow morning. SW winds are expected to drift new snow onto NW-N-NE-E-SE aspects in near treeline and above treeline areas, creating unstable wind slabs in lee areas. Avalanche size is expected at D1 late today and increases to size D2 overnight.

Identify the areas of concern where unstable wind slabs may exist. Use clues such as areas below cornices, wind pillows, and snow surface texture to identify the likely location of wind slabs. Move around these areas cautiously and with an increased margin for error.

recent observations

* Observations made yesterday on Angora Peak (Desolation Wilderness area) and on Silver Peak (Pole Creek area) noted a weaker but still decent snow surface refreeze from the night before.

* Yesterday on Angora Peak, small (size D1) loose wet avalanches were skier triggered during the afternoon hours. After about 2:30 pm, snow surface supportability was lost.

* Snowpack instability is expected to occur near the surface, with the deeper snowpack generally well bonded. The exception might be glide cracks.

 

Weather and CURRENT CONDITIONS
weather summary

A weather system moving through the forecast area today will bring cloud cover, precipitation, and continued moderate to strong SW ridgetop winds through tomorrow morning. Snow levels start out around 7,500' today and lower to around 5,500' early tomorrow morning. Some accumulating snow is expected over the mid to upper elevations, mainly this afternoon and tonight. Tomorrow afternoon, skies begin to clear and wind speeds decrease as high pressure builds in for a warming trend Wednesday through Friday.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 30 to 35 deg. F.
Max. temperature in the last 24 hours: 37 to 41 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 49 mph
Maximum wind gust in the last 24 hours: 91 mph
New snowfall in the last 24 hours: 0 to trace inches
Total snow depth: 101 to 151 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 then becoming mostly cloudy. Chance of showers through the day. Snow levels 7500 feet. Chance of precipitation is 50%. Cloudy. Showers in the evening, then snow showers likely after midnight. Snow levels 7000 feet decreasing to below 7000 feet after midnight. Chance of precipitation is 80%. Mostly cloudy then becoming partly cloudy. Chance of snow showers in the morning. Snow levels below 7000 feet. Chance of precipitation is 40%.
Temperatures: 41 to 47 deg. F. 24 to 29 deg. F. 40 to 45 deg. F.
Mid Slope Winds: Southwest 15 to 30 mph. Gusts up to 45 mph increasing to 60 mph in the afternoon. Southwest 15 to 25 mph with gusts to 60 mph. West around 15 mph. Gusts up to 40 mph decreasing to 25 mph in the afternoon.
Expected snowfall: 70% probability up to 2 inches. 30% probability of 2 to 4 inches. | SWE = less than 0.10 inch. 80% probability of 2 to 6 inches. 20% probability of 6 to 8 inches. | SWE = up to 0.45 inch. 100% probability up to 1 inch. | SWE = less than 0.10 inch.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy then becoming mostly cloudy. Chance of snow showers through the day. Snow levels 7500 feet. Chance of precipitation is 50%. Cloudy. Snow showers in the evening, then snow showers likely after midnight. Snow levels 7000 feet. Chance of precipitation is 85%. Mostly cloudy then becoming partly cloudy. Chance of snow showers through the day. Snow levels below 7000 feet. Chance of precipitation is 40%.
Temperatures: 35 to 41 deg. F. 20 to 25 deg. F. 34 to 40 deg. F.
Ridge Top Winds: Southwest 25 to 35 mph increasing to 30 to 45 mph in the afternoon. Gusts up to 75 mph. Southwest 30 to 45 mph decreasing to 25 to 35 mph after midnight. Gusts up to 75 mph. West 15 to 30 mph. Gusts up to 50 mph decreasing to 35 mph in the afternoon.
Expected snowfall: 70% probability up to 2 inches. 30% probability of 3 to 5 inches. | SWE = up to 0.15 inch. 80% probability of 2 to 6 inches. 20% probability of 6 to 10 inches. | SWE = 0.25-0.50 inch. 100% probability up to 1 inch. | SWE = less than 0.10 inch.
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