THIS AVALANCHE ADVISORY EXPIRED ON April 4, 2016 @ 6:45 am
Avalanche Advisory published on April 3, 2016 @ 6:45 am
Issued by Brandon Schwartz - Tahoe National Forest

Very early this morning while the snow surface remains frozen, LOW avalanche danger exists for all elevations and aspects. Areas of MODERATE avalanche danger will form quickly in response to snow surface melt as the morning progresses. Starting during the mid to late morning hours, human triggered loose wet avalanche activity will become possible on all aspects at all elevations on slopes 35 degrees and steeper.

2. Moderate

?

Above Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

?

Near Treeline
Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2. Moderate

?

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: Loose Wet
  • Type ?
  • Aspect/Elevation ?
  • Likelihood ?
    Certain
    Very Likely
    Likely
    Possible
    Unlikely
  • Size ?
    Historic
    Very Large
    Large
    Small

Air temperatures were in the mid 30s to low 40s for most locations again last night. In open areas, a decent but superficial snow surface refreeze is expected to have occurred last night fueled entirely by radiational cooling. This superficial snow surface refreeze is expected to melt rapidly this morning, exposing the deeper wet snow below and allowing for the possibility of loose wet avalanches today. In treed areas, overnight snow surface refreeze may have been poor. The high sun angle this time of year will allow for snow surface melt to affect all aspects. The most rapid melt will occur on E-SE-S-SW-W aspects. NW-N-NE aspects that are shaded in February will experience more sun exposure, little shade, and snow surface melt today, even at the upper elevations.

Timing of travel in and below avalanche terrain is critical today for avalanche avoidance. Late starts (mid morning and beyond) are not advised for finding the ideal balance of quality recreation and minimum hazard in avalanche terrain. Late starts lead to lower quality recreation and greater avalanche hazard. Pay attention to how the snow feels under equipment and the degree of supportability. When the snow surface feels like it is loosing supportability and equipment is penetrating deeper into wet snow, conditions are becoming ripe for a loose wet avalanche to occur. Human triggered roller balls, pinwheels, and deep penetration into wet snow are the instability clues that exist prior to avalanche occurrence. When signs of wet snow instability are present, stop ascending and move to slopes less than 35 degrees in slope angle without steeper terrain above.

recent observations

Yesterday, observations made on Mt. Tallac (Desolation Wilderness area) and recieved from the Sierra Crest between Mt. Anderson and Mt. Lincoln (Donner Summit area) revealed a poor to decent snow surface refreeze had occured the night before. By the mid morning hours, the snow surface on E-SE aspects had become unsupportable in some areas at low and mid elevations. By noon, signs of loose wet instablity had spread to other aspects, including northerly aspects at 9,000'. Widespread areas of unsupportable wet snow were noted at noon below 7,000'. More specific info below.

Weather and CURRENT CONDITIONS
weather summary

High pressure continues as the dominant weather feature over the forecast area. Above average air temperatures will occur again today. A weather system passing to the north of the forecast area will increase SW ridgetop winds into the moderate speed range this afternoon. Cumulus cloud build up is expected to occur again this afternoon, starting over the Sierra Crest and spreading east. An increase in cloud cover is expected tonight into tomorrow morning. Continued above average air temperatures are forecast for tomorrow.

Weather observations from along the Sierra Crest between 8200 ft. and 8800 ft.
0600 temperature: 34 to 41 deg. F.
Max. temperature in the last 24 hours: 48 to 54 deg. F.
Average wind direction during the last 24 hours: SW
Average wind speed during the last 24 hours: 21 mph
Maximum wind gust in the last 24 hours: 33 mph
New snowfall in the last 24 hours: 0 inches
Total snow depth: 71 to 114 inches
Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 7000 ft. to 8000 ft.
Sunday Sunday Night Monday
Weather: Partly cloudy skies. Partly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 49 to 56 deg. F. 27 to 34 deg. F. 50 to 56 deg. F.
Wind Direction: W SW SW
Wind Speed: Light winds increasing to 10 to 15 mph with gusts to 25 mph in the afternoon. 15 to 20 mph with gusts to 30 mph. 10 to 15 mph
Expected snowfall: 0 in. 0 in. 0 in.
For 8000 ft. to 9000 ft.
Sunday Sunday Night Monday
Weather: Partly cloudy skies. Partly cloudy skies. Mostly cloudy skies, becoming partly cloudy.
Temperatures: 45 to 52 deg. F. 26 to 33 deg. F. 45 to 51 deg. F.
Wind Direction: SW SW SW
Wind Speed: 10 to 15 mph, increasing to 20 to 25 mph with gusts to 35 mph in the afternoon. 15 to 25 mph with gusts to 40 mph. 15 to 20 mph with gusts to 35 mph.
Expected snowfall: 0 in. 0 in. 0 in.
Disclaimer

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.

For a recorded version of the Avalanche Advisory call (530) 587-3558 x258