THIS AVALANCHE FORECAST EXPIRED ON March 26, 2019 @ 6:45 am
Avalanche Forecast published on March 25, 2019 @ 6:45 am
Issued by Brandon Schwartz - Tahoe National Forest

MODERATE avalanche danger at all elevations today due to the possibility of loose wet avalanches and unlikely wind slab avalanches.

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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Rapid warming conditions are expected this morning before increasing high level cloud cover later today has a significant effect on reducing incoming solar radiation. Many locations at the lower and middle elevations remained above freezing last night, just above the inversion layer of cold air on the mountain valley floors. These areas already have a head start on warming prior to sunrise. Small loose wet avalanches are expected again today with most instability occurring on E-SE-S-SW-W aspects. Loose wet avalanches are expected to a lesser degree on NW-N-NE aspects but are increasingly possible as higher spring sun angles have more influence on northerly aspects. Avalanche size D1 is expected today with the possibility of an isolated size D2.

Rollerballs and pinwheels will be the indicators that loose wet instability is present. Consequences from what would otherwise be a small inconsequential size D1 avalanche will come from secondary terrain hazards such as being pushed into rocks, trees, over cliffs, or into terrain traps. Use low angle slopes to reduce the hazard as needed. Plan appropriately for the timing of travel in sun exposed avalanche terrain and exit steep terrain before daytime warming creates problematic instability.

Avalanche Problem 2: Wind Slab
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A wind slab avalanche problem is unlikely today but there are a couple of things going on. First, isolated wind slab instability lingered unexpectedly into yesterday with a couple of human triggered size D1 avalanches reported. Second, ridgetop winds are strong today and will be able to drift what little snow remains available for transport in ridgetop areas. Isolated human triggered wind slab avalanches are unlikely but not impossible today in near treeline and above treeline terrain on NW-N-NE-E aspects.

Look for signs of recent wind slab avalanche activity from the past two days and keep an eye out for any areas of blowing snow. Exercise normal caution around these areas, taking into consideration how terrain may magnify consequences of a small unexpected avalanche

recent observations

* Numerous natural and human triggered loose wet avalanches were reported yesterday around the forecast area on sun exposed slopes. Avalanche size was almost all D1 with one report of a size D2.

* A couple of isolated human triggered size D1 wind slab avalanches occurred yesterday, but wind slab avalanches were very limited relative to the number of people moving through recently wind loaded terrain.

* Recent avalanches have all been focused around the layer of snow at the surface, with the deeper snowpack generally well bonded and lacking problematic weak layers.

Weather and CURRENT CONDITIONS
weather summary

A sunny start to today will give way to increasing high level cloud cover expected to arrive sometime during the 11 am to 3 pm timeframe. Cloud cover is expected to lower and thicken further late today with increasing chances for light snowfall. Snowfall will then continue into Tuesday and Wednesday. Ridgetop winds are increasing towards strong in speed out of the S to SW this morning with gusts to 90 mph expected today. Maximum daytime air temperatures are forecast to warm above freezing today for most locations. Check with NWS Reno for the latest info on the significant snowfall expected Wednesday.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 27 to 32 deg. F.
Max. temperature in the last 24 hours: 31 to 35 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 27 mph
Maximum wind gust in the last 24 hours: 67 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 110 to 156 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. Slight chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 15%. Mostly cloudy. Chance of snow through the night. Snow levels below 7000 feet. Chance of precipitation is 70%. Cloudy. Snow likely. Snow levels below 7000 feet. Chance of precipitation is 70%.
Temperatures: 35 to 43 deg. F. 26 to 31 deg. F. 32 to 40 deg. F.
Mid Slope Winds: South 20 to 35 mph with gusts to 70 mph. Southwest 15 to 30 mph with gusts to 65 mph. Southwest 15 to 25 mph increasing to 20 to 35 mph in the afternoon. Gusts up to 60 mph.
Expected snowfall: Up to 2 inches. | SWE = less than 0.10 inch. 70% probability of 1 to 3 inches. 30% probability of 4 to 6 inches. | SWE = up to 0.25 inch. 60% probability 1 to 4 inches. 40% probability of 4 to 6 inches. | SWE = up to 0.25 inch.
For 8000 ft. to 9000 ft.
Monday Monday Night Tuesday
Weather: Partly cloudy. Slight chance of snow in the afternoon. Snow levels below 7000 feet. Chance of precipitation is 15%. Mostly cloudy. Chance of snow. Snow levels below 7000 feet. Chance of precipitation is 50%. Cloudy. Snow likely. Snow levels below 7000 feet. Chance of precipitation is 70%.
Temperatures: 31 to 37 deg. F. 24 to 29 deg. F. 29 to 34 deg. F.
Ridge Top Winds: South 35 to 55 mph with gusts to 90 mph. Southwest 35 to 55 mph shifting to the south 30 to 45 mph after midnight. Gusts up to 85 mph. Southwest 30 to 45 mph with gusts to 80 mph.
Expected snowfall: Up to 2 inches. | SWE = less than 0.10 inch. 60% probability of 1 to 3 inches. 40% probability of 4 to 6 inches. | SWE = 0.15-0.25 inch. 60% probability of 1 to 4 inches. 40% probability of 4 to 8 inches. | SWE = up to 0.25 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