|Avalanche Advisory published on March 7, 2014 @ 6:52:||
This advisory is valid for 24 hours
Issued by Andy Anderson - Tahoe National Forest
Pockets of MODERATE avalanche danger will form on the sun exposed E-SE-S-SW-W aspects on slopes 35 degrees and steeper today. Daytime warming and strong March sunshine will allow conditions conducive for loose wet avalanches to form on those aspects.
|Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.||Natural avalanches unlikely; human-triggered avalanches possible.||Small avalanches in specific areas; or large avalanches in isolated areas.|
Snow showers yesterday afternoon and evening gave way to clearing skies and overnight lows in the 20's above 7000 ft. Expect sunny skies, light easterly winds, and daytime highs in the upper 30's to upper 40's above 7000 ft. today. The high pressure causing this dry sunny weather will remain over the area through tomorrow and should push temperatures up almost 10 degrees into the upper 40's and low 50's above 7000 ft tomorrow. The forecast calls for the winds to increase some and shift to the south tomorrow ahead of another storm expect to arrive on Sunday evening.
Yesterday on Castle Peak, hard frozen rain crusts with 6-12 inches of wet snow below them existed on all aspects before 9 am. On any slopes that received sunshine the surface crust quickly melted leaving behind wet unconsolidated snow. Ski cuts and small cornice drops on the E-SE-S-SW aspects resulted in large pinwheels and loose wet snow sluffs by 10 am. On the more shaded NW-N-NE aspects the frozen surface crust remained frozen, and observations and tests did not reveal any signs of instability on these aspects. Above 8000 ft. on the northerly aspects, the frozen surface crust would support a skier. Below 8000 ft. its strength remained more variable: sometimes breaking under the weight of a skier and sometimes supporting the skier's weight.
Cold temperatures and clear skies should have allowed a strong refreeze to occur last night on all aspects. The strong March sunshine and daytime highs well above freezing may melt through this refreeze on the sun exposed E-SE-S-SW-W aspects today. Once the frozen surface melts loose wet snow instabilities will again become possible on these aspects. Most of these wet snow instabilities should remain limited to roller balls, pinwheels, and small wet snow sluffs, but some of them could entrain enough snow to cause problems for backcountry travelers. The shaded northerly aspects should remain frozen today.
|CURRENT CONDITIONS Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.|
|0600 temperature:||21 to 28 deg. F.|
|Max. temperature in the last 24 hours:||27 to 38 deg. F.|
|Average wind direction during the last 24 hours:||Before 10 pm yesterday: SW | After 10 pm: E|
|Average wind speed during the last 24 hours:||Before 10 pm yesterday: 35-45 mph | After 10 pm: 10-20 mph|
|Maximum wind gust in the last 24 hours:||83 mph|
|New snowfall in the last 24 hours:||0 to 1 inches|
|Total snow depth:||43 to 57 inches|
|Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS|
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.