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.

A break in snowfall will occur today under mostly cloudy skies before the next major storm system impacts the forecast area tonight through tomorrow. Snowfall amounts above 7,000' for the past 24 hours have exceeded forecast expectations with 2 to 14 inches of new snow. Last night new snow amounts of 2 to 8 inches accumulated across the forecast area with the greatest amounts along the Sierra Crest in the northern half of the forecast area. Ridgetop winds were moderate in speed out of the southwest to west for most of the last 24 hours. Early this morning winds have decreased to light in speed. Winds are forecast out of the southwest today with an increase to moderate in speed during the morning hours before becoming light in speed again this afternoon. Air temperatures above 8,000' have fallen into the low to mid teens this morning. Temperatures are expected to warm into the mid 20s to near freezing below 8,000' and into the upper teens to mid 20s above 8,000' today.

Observations:

Observations made yesterday on the Far East Ridge of Tamarack Peak (Mount Rose area) revealed instability and human triggered avalanche activity both above and below treeline in wind affected and wind loaded areas. Several slab avalanches were intentionally skier triggered just below treeline on wind loaded north aspects at 9400' and in near treeline terrain up off the ridgelines at 9,700'. Cracking, shooting cracks and collapsing were all common in wind loaded terrain. All slab failures were 1' deep in near treeline terrain and up to 2' deep on the exposed ridge at 9,700'. Of note, snowpit data collected in this area gave no clear indications of instability and was showing signs that the storm snow had gained some strength. All informal tests pointed towards easy triggering of wind slabs in NW-N-NE-E aspects at or above treeline (photos, video, more info).

Observations made yesterday on Jake's Peak (West Shore Tahoe area) revealed below treeline evidence of skier triggered sluffing of the top 4 inches was widespread on Sunday in open areas steeper than 37 degrees. Monday there was no evidence of instability below 8,500'. From 8,500' on up to 9,200' at the summit minimal cracking up to 2 feet long occurred while trail breaking in lightly wind effected areas below treeline. At treeline a pronounced surface slab existed in wind loaded areas on NE-E aspects. Snowpit data just above treeline along the summit ridge at 9,160' on a NNE aspect produced inconsistent results on a buried wind slab with its weak layer 20 inches below the snow surface. This wind slab is likely difficult to trigger until the exact right trigger point is found. Minimal skier triggered sluffing of the top 2 inches of new snow in below treeline areas was noted on the descent in terrain steeper than 37 degrees (pit profile, video, more info).

Avalanche Concern #1: Wind Slabs

Ongoing wind loading and wind transport of new snow and storm snow on the ground has continued to build wind slabs both above and below treeline. These slabs are largest and most pronounced in near and above treeline terrain, but exist in wind effected areas below treeline as well. The greatest areas of instability are expected on NW-N-NE-E-SE-S aspects directly below cornice features and wind pillows. Snowpack failure is expected to remain limited to the top 1 to 3 feet of the snowpack. Failure deeper into the recent storm snow is becoming increasingly less likely, but is certainly not impossible given the right combination of terrain, snowpack, and trigger.

Avalanche Concern #2: Warming instability

As air temperatures climb to near freezing and the late March sun shines through breaks in cloud cover or thin areas of cloud cover today, some warming instability may occur. In some areas, this may just turn loose surface snow that produces human triggered sluffing during the early morning hours into shallow but cohesive slabs by the mid day or afternoon hours. In areas that receive more significant warming and sunshine, larger slabs of recently wind loaded snow may become more reactive on E-SE-S-SW aspects, especially in recently wind load and cross loaded areas below 8,000'.

The bottom line:

Avalanche danger is MODERATE for all elevations and aspects on slopes 35 degrees and steeper today due to a combination of recent wind loading and warming instability. Small to medium size human triggered avalanches remain possible today in a variety of areas. Large human triggered avalanches remain possible in isolated areas. Increasing avalanche danger is expected tonight into Wednesday.

Brandon Schwartz - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	10 to 16 deg. F.
Max. temperature in the last 24 hours:	20 to 27 deg. F.
Average wind direction during the last 24 hours:	West Southwest
Average wind speed during the last 24 hours:	37 mph
Maximum wind gust in the last 24 hours:	71 mph
New snowfall in the last 24 hours:	2 to 14 inches
Total snow depth:	124 to 190 inches

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

For 7000-8000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Mostly cloudy skies.	Cloudy skies with light snow likely in the evening. Snow after midnight.	Cloudy skies with snow.
Temperatures:	23 to 30 deg. F.	17 to 24 deg. F.	23 to 30 deg. F.
Wind direction:	SW	S	S
Wind speed:	10 to 15 mph. Gusts to 30 mph in the morning.	Around 10 mph with gusts to 25 mph.	10 to 20 mph with gusts to 40 mph.
Expected snowfall:	O in.	2 to 4 in.	6 to 12 in.
For 8000-9000 ft:
	Tuesday:	Tuesday Night:	Wednesday:
Weather:	Mostly cloudy skies.	Cloudy skies with light snow likely in the evening. Snow after midnight.	Cloudy skies with snow.
Temperatures:	18 to 25 deg. F.	13 to 20 deg. F.	20 to 26 deg. F.
Wind direction:	SW	S	S
Wind speed:	15 to 25 mph with gusts to 45 mph in the morning. Winds decreasing to 10 to 20 mph in the afternoon.	10 to 20 mph in the evening. Winds increasing to 15 to 25 mph with gusts to 35 mph.	25 to 35 mph with gusts to 55 mph. Winds increasing to 30 to 45 mph with gusts to 65 mph in the afternoon.
Expected snowfall:	O in.	3 to 6 in.	6 to 12 in.