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 Wednesday, December 13, 2006 at 7:01 am

Our SAC ski day tickets for Mt. Rose are not selling very well. We need your help! This is one of our two largest fund raisers for this season. We currently only have enough funds in the bank to operate through January. If you use this page with any regularity, please help to keep SAC alive and running by purchasing a SAC ski day lift ticket. Even if you do not plan on skiing that day, your donation will help to keep the center running through this season. If you are in a position to purchase more than one ticket, please do so. Without your support, we will be laid off, the center will close, and this product will cease to exist. Please click on the SnowBomb.com link above and purchase your ticket today! The skiing is getting better by the minute, especially at the upper elevations.

Warm, unsettled weather remains over the forecast area. High elevation rain will affect the forecast area today with snow levels above 8500'. The warm weather and rain will come to an end tomorrow afternoon as a strong cold front moves in. Some models predict that this cold front could give us 16" of cold dry snow overnight on Thursday. Ridgetop winds increased yesterday afternoon and continued through the night. They will moderate some today.

It stayed warm overnight. While the temperatures stay high, the snowpack will stay unconsolidated. As it warms up even more today, expect to see some small loose snow avalanches. There is also a possibility of the water in the snowpack percolating to the ground or to one of the crusts that exist in the snowpack and lubricating that layer. More rain is also expected below 8500' today. The rain will add weight and subtract cohesion in the snow pack. The lubrication and the added weight of the recent precipitation could cause some wet slab avalanches to occur in the new snow from yesterday or on those lubricated crust layers or even the ground in some areas. Any of these slides will still be small and isolated because of huge variation in snow depth and anchoring across most of our starting zones. The most suspect slopes will be below 9000' on steep NW-N-NE-E windloaded aspects where the crusts and more consistent snow cover exist and any steep southerly aspects that had consistent snow cover on them before the storm (very few of these exist). The warmth and rain is also helping to densify some of our weak layers. The wet snow is sticking to all of the uncovered obstacles in our starting zones and will help give us much more widespread and consistent snow cover. This base will help to dramatically improve the skiing as we get more snow on top of it. The warmth and rain will strengthen our snowpack as it starts to freeze with the arrival of the cold front on Thursday afternoon. The free water in the snowpack will turn into ice and act like cement for snow. This will help any weaknesses that are persisting to bond to the layers around them and build a stronger snowpack overall.

Near and above treeline, avalanche danger is LOW and will increase to MODERATE as the day warms up on those steep NW-N-NE-E windloaded aspects and any steep southerly aspects that had consistent snow cover on them before the storm (very few of these exist). Below treeline, avalanche danger is LOW and will increase to MODERATE as the day warms up and we get more rain.

Remember that even though you are unlikely to trigger any large avalanches, a small avalanche can be disastrous depending on the terrain. Be aware of secondary exposures such as rockbands, cliffs, gullies, and creek beds, where the consequences of being caught in a small avalanche are greatly magnified.

Andy Anderson , Avalanche Forecaster

Today's Central Sierra Weather Observations:
0600 temperature at Sierra Crest (8,700 feet):
32 deg. F
Max. temperature at Sierra Crest past 24 hours:
33 deg. F
Average wind direction at Sierra Crest past 24 hours:
westsouthwesterly
Average wind speed at Sierra Crest past 24 hours:
35 mph
Maximum wind gust at Sierra Crest past 24 hours:
85 mph
New snow fall at 8,200 feet past 24 hours:
rain
Total snow depth at 8,200 feet:
19 inches
Mountain Weather Forecast For Today:
Cloudy skies with rain showers. Snow above 8500'
Temperature forecast for 8,000 to 9,000 feet:
30-39 deg. F
Ridgetop winds forecast for the Sierra Crest:
west at 20-35 mph, G 65 mph
Snowfall expected in the next 24 hours:
3-6 inches above 8500 feet
2 Day Mountain Weather Forecast:

7000 to 8000 Feet
For today, cloudy skies with rain showers. Daytime highs of 39 to 45 degrees F. Overnight lows 30 to 35 degrees F. Thursday will be mostly cloudy with rain in the early morning turning to snow in the evening as a cold front moves in. Some models are forecasting up to 16" of snow overnight on Thursday. Daytime highs 40 to 45 degrees F. Winds out of the west at 10 to 20 mph.

Above 8000 Feet
For today, cloudy skies with rain showers and snow above 8500'. Daytime highs 30 to 39 degrees F. Snow accumulation 3 to 6 inches above 8500'. Overnight lows around 30 to 35 degrees F. Thursday will be mostly cloudy with rain in the early morning turning to snow in the evening as a cold front moves in. Some models are forecasting up to 16" of snow overnight on Thursday. Daytime highs 32 to 38 degrees F. Winds out of the west at 15-30mph in the morning and increasing to 35-45mph with gusts to 80 as the cold front moves in Thursday afternoon and evening.

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:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.
For 8000-9000 ft:
	Wednesday:	Wednesday Night:	Thursday:
Weather:
Temperatures:	deg. F.	deg. F.	deg. F.
Wind direction:
Wind speed:
Expected snowfall:	O in.	O in.	O in.