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.


This Avalanche Advisory was published on February 14, 2010:


February 14, 2010 at 7:59 am

This morning the avalanche danger is LOW for all elevations and aspects. Pockets of MODERATE danger will form on E-SE-S-SW-W aspects steeper than 35 degrees due to daytime warming today. Use normal caution when traveling in the backcountry.


Forecast Discussion:


A strong high-pressure ridge will keep the weather warm and dry over the forecast area. The forecast calls for temperatures to climb another 3-7 degrees over yesterday's high temperatures during the day. A low-pressure system north of the area will cause a layer of high clouds to linger over the region through tomorrow.

Observations:

Skiers reported numerous wet, point-release avalanches on steep, sun-exposed slopes on Incline Lake Peak (Mt. Rose backcountry) yesterday. They also triggered one small wet-slab avalanche on a 38-degree, sun-exposed slope below treeline (photo and more information). On Silver Peak (Pole Creek drainage), 1-3 inches of weak, wet, heavy, slushy snow existed on the sun-exposed SE-S aspects by noon. Ski-cuts on 38-degree test slopes did release some small roller-balls in this area. On the more northerly aspects, a thin, mostly-breakable crust existed on top of soft, unconsolidated snow up to 8000' in the Silver Peak area. On the sheltered northerly aspects above 8000', 3-4" of soft, unconsolidated snow remains on the surface. A mix of hard wind-slabs, wind-crusts, and soft snow existed on the surface on the more exposed northerly slopes near and above treeline. Layer bonding tests, hand-pits, and ski-cuts on several steep test slopes indicated a mostly stable snowpack on the more northerly aspects.

Avalanche Concerns:

A light overnight refreeze and warm daytime temperatures will work to create more wet-snow instabilities today. Most of these wet-snow instabilities should take the form of roller-balls and point-release slides. Like yesterday, small wet slabs may become possible as well. These slides could entrain enough snow to push a person off course and into trouble. These instabilities will mostly likely exist on sun-exposed E-SE-S-SW-W aspects. If the forecast area sees more sunshine than forecasted today, these wet-snow instabilities will become more widespread.


The bottom line:

This morning the avalanche danger is LOW for all elevations and aspects. Pockets of MODERATE danger will form on E-SE-S-SW-W aspects steeper than 35 degrees due to daytime warming today. Use normal caution when traveling in the backcountry.


Andy Anderson - Avalanche Forecaster, Tahoe National Forest


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

0600 temperature: 30-33 deg. F.
Max. temperature in the last 24 hours: 34-40 deg. F.
Average wind direction during the last 24 hours: Southwest
Average wind speed during the last 24 hours: 10-15 mph
Maximum wind gust in the last 24 hours: 29 mph
New snowfall in the last 24 hours: O inches
Total snow depth: 69-107 inches

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

For 7000-8000 ft:

  Sunday: Sunday Night: Monday:
Weather: Mostly cloudy Mostly cloudy Mostly cloudy
Temperatures: 41-48 deg. F. 24-30 deg. F. 42-49 deg. F.
Wind direction: West southwest Southwest Variable
Wind speed: 10 mph 10 mph Light
Expected snowfall: O in. O in. O in.

For 8000-9000 ft:

  Sunday: Sunday Night: Monday:
Weather: Mostly cloudy Mostly cloudy Mostly cloudy
Temperatures: 41-47 deg. F. 21-28 deg. F. 42-48 deg. F.
Wind direction: West southwest West West
Wind speed: 10-15 mph with gusts to 35 mph 10-20 mph with gusts to 35 mph 10 mph
Expected snowfall: O in. O in. O in.