THIS AVALANCHE FORECAST EXPIRED ON March 2, 2019 @ 6:54 am
Avalanche Forecast published on March 1, 2019 @ 6:54 am
Issued by Steve Reynaud - Tahoe National Forest

MODERATE avalanche danger will exist at all elevations with wind slab and loose wet avalanche problems.  Periods of intense sunshine along with rapid warming could increase the amount of avalanche activity today.  Avalanche danger is expected to rise tomorrow as another storm impacts our forecast area.

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: Wind Slab
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Wind slabs and cornices will remain reactive on NW-N-NE-E-SE aspects in near and above treeline terrain.  Strong SW winds will continue through today at the upper elevations transporting snow and adding to existing wind slabs and cornices.  In sun exposed areas, wind slab avalanches could become weak and take on wet slab characteristics.  Large wind slab avalanches that have formed during this storm cycle still have the potential to be human triggered.

Look for blowing snow, cornice formation, and wind pillows.  Make a plan with your group to avoid wind loaded terrain and areas below large cornices.

Avalanche Problem 2: Loose Wet
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For areas that see intense March sunshine and rapid warming today, loose wet avalanches will become possible on all aspects and elevations.  Most loose wet instabilities are expected to be in the form of roller balls and pinwheels and be small in size (D1).  Larger loose wet avalanches (up to size D2) will be possible if intense solar radiation occurs.

Monitor cloud cover and temperatures throughout your tour.  Wet, heavy, surface snow along with roller balls or pinwheels will indicate that the snow surface is warming and loosing strength.  Change aspects or move to different terrain if rapid warming is occurring.    

recent observations

* Wind transported snow was seen on Mt. Judah (Donner Summit area).  Large cornices and wind slabs were sensitive to the weight of a skier.  Wind slabs were up to 2' deep with ECT-P's on wind loaded test slopes.

Wind loading was observed along Frog Lake Ridge in the Carson Pass area.  Multiple layers of graupel were identified in the recent storm snow, both showed limited signs of instability with snowpack tests.

* Tree bombing, rollerballs, small loose wet avalanches, and rain runnels were noted yesterday, mainly below 7000'.

* Cornices continue to be large, fragile, and break off easily.

Weather and CURRENT CONDITIONS
weather summary

A rare quiet day forecasted with partly cloudy skies and strong SW winds at the higher elevations.  Cloud cover will vary by location with some areas receiving periods of sun.  Temperatures will be in the low to mid 30's above 8000'.  A winter weather advisory goes into effect from midnight through 6pm Saturday.  6 to 12'' are forecasted at lake level with 1 to 2' above 7000'.  Snow levels are looking to be below 6000'.  Another AR storm is forecasted for the middle of next week.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 24 to 28 deg. F.
Max. temperature in the last 24 hours: 30 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 55 to 70 mph
Maximum wind gust in the last 24 hours: 93 mph
New snowfall in the last 24 hours: 1 to 5 inches
Total snow depth: 111-120 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Friday Friday Night Saturday
Weather: Mostly cloudy. Slight chance of snow through the day. Snow levels below 7000 feet. Chance of precipitation is 25%. Cloudy. Chance of snow in the evening, then snow after midnight. Snow levels below 7000 feet. Chance of precipitation is 75%. Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 95%.
Temperatures: 33 to 38. deg. F. 23 to 28. deg. F. 30 to 35. deg. F.
Mid Slope Winds: Southwest 15 to 25 mph with gusts to 75 mph. Southwest 15 to 25 mph with gusts to 60 mph in the evening becoming light. Light winds. Gusts up to 25 mph increasing to 40 mph in the afternoon.
Expected snowfall: Up to 1 inch. | SWE = less than 0.10 inch. 70% probability of 2 to 3 inches. 30% probability of 1 to 2 inches. | SWE = up to 0.20 inch. 80% probability of 6 to 10 inches. 20% probability of 10 to 14 inches. | SWE = 0.60-0.95 inch.
For 8000 ft. to 9000 ft.
Friday Friday Night Saturday
Weather: Mostly cloudy then becoming partly cloudy. Slight chance of snow through the day. Snow levels below 7000 feet. Chance of precipitation is 20%. Mostly cloudy. Chance of snow in the evening, then snow after midnight. Snow levels below 7000 feet. Chance of precipitation is 75%. Cloudy. Snow. Snow levels below 7000 feet. Chance of precipitation is 95%.
Temperatures: 29 to 35. deg. F. 21 to 26. deg. F. 27 to 32. deg. F.
Ridge Top Winds: Southwest 30 to 50 mph with gusts to 80 mph. Southwest 30 to 40 mph with gusts to 70 mph becoming south 15 to 30 mph with gusts to 50 mph after midnight. South 15 to 30 mph increasing to southwest 25 to 40 mph in the afternoon. Gusts up to 70 mph.
Expected snowfall: Up to 1 inch. | SWE = less than 0.10 inch. 70% probability of 2 to 4 inches. 30% probability of 1 to 2 inches. | SWE = up to 0.20 inch. 80% probability of 8 to 12 inches. 20% probability of 12 to 16 inches. | SWE = 0.65-1.00 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