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 advisory was posted on Monday, January 8, 2007 at 6:44 am

Warm daytime air temperatures will continue across the forecast area today and Tuesday. Ridgetop winds have become easterly over all areas this morning and will continue through the day today. A major cooling trend is still on track to impact the forecast area Tuesday night.

Large diurnal air temperature swings are causing significant recrystalization of surface and near surface snow. The largest impact has been observed in the 6,800' to 8,000' elevation range where surface hoar up to 12mm (1/2 inch) is widespread in wind protected areas on northerly aspects. This surface hoar is surviving warm daytime air temperatures due to the low sun angles that occur this time of year. These sun angles are allowing northerly aspects to remain very shaded throughout the day and are allowing snow surface temperatures to remain below freezing. With a major cool down expected to begin tomorrow night, there is an excellent chance that surface hoar will become buried by the next snowfall. This would cause widespread instability and the potential for shooting crack and avalanche propagation over large areas. Recrystalization of near surface snow is preserving powder conditions below treeline on northerly aspects. Warm air temperatures yesterday created melt-freeze crusts on SE-S-SW aspects up to around 8,500'.

Recent winds have created hard slab conditions on the majority of aspects above treeline. Yesterday, explosive work in the Mount Rose area created two small hard slab avalanches on NE aspects around 9,000', that failed just above ground level. The probability of a single skier, snowboarder, or snowmobile triggering a hard slab avalanche remains unlikely at this time, due to the smaller trigger size than that of an explosive. Normal caution should still be taken as an avalanche event is unlikely, but not impossible. Expose only one person at a time to steep slopes, both when on the slope and when regrouping below the slope. Avoid trigger points such as slope convexities, areas near isolated rocks, single trees, and near cliff bands. Any areas where the snow near you sounds hollow should be avoided. Avoiding trigger points is the fine art of the uphill and the down hill line made by backcountry travelers.

Avalanche danger is LOW at all elevations and on all aspects at this time.

Brandon Schwartz, Avalanche Forecaster

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Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet): 27 deg. F
Max. temperature at Sierra Crest past 24 hours: 33 - 40 deg. F
Average wind direction at Sierra Crest past 24 hours: easterly
Average wind speed at Sierra Crest past 24 hours: 31 mph
Maximum wind gust at Sierra Crest past 24 hours: 43 mph
New snow fall at 8,200 feet past 24 hours: 0 inches
Total snow depth at 8,200 feet: 41 inches

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Mountain Weather Forecast For Today:
Mostly sunny skies
Temperature forecast for 8,000 to 9,000 feet: 38 - 48 degrees F.
Ridgetop winds forecast for the Sierra Crest: Easterly 25 - 35 mph, G 45 mph
Snowfall expected in the next 24 hours: 0 inches

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2 Day Mountain Weather Forecast:
7000 to 8000 Feet
For today, mostly sunny skies. Day time highs 40 to 50 degrees F. East winds 5 to 15 mph. Overnight, clear with lows 21 to 31 degrees F. Southeast winds at 5 to 10 mph, shifting to southwest after midnight. Tuesday will be sunny with daytime highs 41 to 51 degrees F. Southwest winds at 15 to 25 mph are expected.

Above 8000 Feet
For today, mostly sunny skies. Daytime highs 38 to 48 degrees F. East winds 25 to 35 mph with gusts to 45 mph. Overnight, clear with lows 28 to 38 degrees F. Southeast winds at 10 to 15 mph, shifting to southwest after midnight. Tuesday will be sunny and with daytime highs 38 to 48 degrees F. Southwest winds at 15 to 25 mph are expected.

The bottom line:

Andy Anderson - Avalanche Forecaster, Tahoe National Forest

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

0600 temperature:	deg. F.
Max. temperature in the last 24 hours:	deg. F.
Average wind direction during the last 24 hours:
Average wind speed during the last 24 hours:	mph
Maximum wind gust in the last 24 hours:	mph
New snowfall in the last 24 hours:	O inches
Total snow depth:	inches

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

For 7000-8000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Monday:	Monday Night:	Tuesday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.