This avalanche advisory is provided through a partnership between the Tahoe National Forest and the Sierra Avalanche Center. This advisory 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 advisory applies only to backcountry areas outside established ski area boundaries. This advisory describes general avalanche conditions and local variations always occur. This advisory expires 24 hours after the posted time unless otherwise noted. The information in this advisory is provided by the USDA Forest Service who is solely responsible for its content.

High pressure is in place over the forecast area this morning. A warm and sunny day with calm wind in the morning, increasing to light to moderate in speed from the west is expected this afternoon. An air temperature inversion is in place this morning with nearly all remote sensors above 7,000' reporting above freezing air temperatures. Air temperatures below freezing are reported only below 7,000' in nearly all locations. Air temperatures at the 8,000' level are 10 to 15 deg F. warmer this morning than on Friday morning. A cold front is expected to impact the forecast area tonight, increasing winds and lowering maximum daytime air temperatures up to 20 deg F. on Sunday.

Yesterday, observations made on Mt. Tallac (Desolation Wilderness area) indicated stable snow on all aspects during the morning hours. Some areas of potential wet snow instability with wet snow up to 1 foot deep formed in sun exposed areas in the afternoon. Cold unconsolidated snow surface conditions were found above 8,200' on N aspects below treeline. Supportable corn snow conditions were found below 8,000' on open SE aspects. "Almost corn" snow conditions were reported in the South Bowl between 8,000' and 9,000'. Observations made on Signal Peak (Donner Summit area) indicated similar conditions with supportable corn snow on open NE and E aspects below 8,000'. Wet unsupportable snow was observed below treeline by mid day. No new avalanche activity was reported or observed to have occurred yesterday.

Overnight, a fair refreeze of the snow surface is expected to have occurred from radiational cooling of the snowpack under clear skies, despite above freezing air temperatures. With air temperatures in the upper 30s already in place this morning above 7,000', snow surfaces will melt very quickly today once the sun's radiation hits the snow surface. Don't be fooled by a seemingly well frozen snowpack at lower elevation trailheads this morning due to the air temperature inversion. Only a short window for good corn snow recreation will exist this morning before potentially dangerous avalanche conditions start to develop. If you are reading this advisory several hours after it posted and are not already out the door, you are probably too late for safe recreation on E-SE-S-SW-W aspects today due to the expected rapid warming. Human triggered wet snow avalanches will become possible today once the snow surface is no longer supportable. If you find yourself sinking into wet snow up to the top of your boots, move to a more westerly aspect, northerly aspect, or to low angle terrain in order to minimize the potential of becoming caught in an avalanche. Wet snow avalanches are more difficult to trigger than storm snow avalanches, but it happens every year.

 

The bottom line:

Early this morning, avalanche danger is LOW for all elevations and aspects. Avalanche danger will quickly rise to MODERATE at all elevations on E-SE-S-SW-W aspects, 37 degrees and steeper in response to daytime warming.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

Weather Observations from along the Sierra Crest between 8200 ft and 8800 ft:

0600 temperature:	38 deg. F.
Max. temperature in the last 24 hours:	39 to 49 deg. F.
Average wind direction during the last 24 hours:	East shifting to north.
Average wind speed during the last 24 hours:	20 mph
Maximum wind gust in the last 24 hours:	45 mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	144 inches

Two-Day Mountain Weather Forecast - Produced in partnership with the Reno NWS

For 7000-8000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny skies.	Mostly clear skies.	Mostly sunny skies.
Temperatures:	49 to 57 deg. F.	29 to 34 deg. F.	31 to 36 deg. F.
Wind direction:	N shifting to W	W	NW shifting to N
Wind speed:	Light winds becoming 10 to 15 mph in the afternoon.	10 to 15 mph with gusts to 30 mph. Increasing to 15 to 25 mph with gusts to 45 mph after midnight.	15 to 20 mph with gusts to 35 mph. Decreasing to 10 to 15 mph with gusts to 25 mph in the afternoon.
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Saturday:	Saturday Night:	Sunday:
Weather:	Sunny skies.	Clear skies in the evening, becoming partly cloudy.	Mostly sunny skies.
Temperatures:	43 to 49 deg. F.	22 to 30 deg. F.	25 to 31 deg. F.
Wind direction:	N shifting to W	W	NW shifting to N
Wind speed:	Up to 10 mph in the morning, increasing to 10 to 20 mph with gusts to 35 mph in the afternoon.	20 to 35 mph with gusts to 65 mph. Increasing to 30 to 45 mph with gusts to 85 mph after midnight.	35 to 45 mph with gusts to 100 mph. Decreasing to 15 to 30 mph with gusts to 60 mph by afternoon.
Expected snowfall:	O in.	O in.	O in.