NOAA is forecasting 34-66″ of snow to fall in California’s mountains in the next 3 days.

Snow advisories have been issued for both Lake Tahoe and Mammoth and everything in between.

TAHOE:

* Tuesday afternoon through Wednesday afternoon: Moderate snow with accumulations of 
5 to 10 inches, except 10 to 18 inches west of Highway 89, are expected. For 
Wednesday night through Thursday:  2 to 4 feet possible above 7000 feet. 
Below 7000 feet, 8 to 18 inches, possibly as much as 15 to 30 inches if 
precipitation remains all snow. - NOAA Reno, NV today

MAMMOTH:

* Tuesday-Wednesday: Moderate snow with accumulations of up
  to 4 inches east of Highway 395 and 6 to 18 inches west of
  Highway 395 above 7000 feet, are expected. Wednesday night
  through Thursday: 2 to 4 feet possible west of Highway 395 above
  7000 feet, with 10 to 20 inches elsewhere above 7000 feet.
  Between 6000 and 7000 feet, up to 6 inches is possible. 
  - NOAA Reno, NV today

There are currently snow advisories in California from the Oregon border clean down to the border of Mexico.

The National Weather Service has issued a Winter Weather Advisory and a Winter Storm Watch for California. 

The Winter Weather Advisory is in effect Tuesday – Wednesday and the Winter Storm Watch is in effect Wednesday – Thursday.

Wednesday Night – Thursday Night is expected to be the highest impact period. 

High winds and heavy snowfall are expected to result in whiteout conditions.

Driving is strongly discouraged over the Sierra Nevada on Thursday.

Snow levels are forecasted to hover between 4,500ft and 5,500ft for Tuesday-Wednesday.

Snow levels are forecast to rise as high as 6,000ft-7,000ft for Wednesday-Thursday.

Snow levels looks to start near 6000 feet [Wednesday night] to start 
then possibly rise to7000 feet for about 6 hours before falling again. 
However, with heavy precip falling, snow levels are known to be more static
despite warming aloft and become more isothermal. There is still a
chance this could occur (25%) keeping it all snow to 6000 feet.
- NOAA Reno, NV

The 6-10 day outlook calls for above average temperatures and below average precipitation in California.

Additional Storm Info:

Winter Storm Watch for Lake Tahoe:

URGENT - WINTER WEATHER MESSAGE
National Weather Service Reno NV
426 AM PST Tue Jan 15 2019

Greater Lake Tahoe Area-
Including the cities of South Lake Tahoe, Truckee, Stateline,
and Incline Village

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 4 PM THIS
AFTERNOON TO 4 PM PST WEDNESDAY...
...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY AFTERNOON
THROUGH LATE THURSDAY NIGHT...

* CHANGES...Increased snowfall amounts for tonight.

* WHAT...Tuesday afternoon through Wednesday afternoon: Moderate
  snow with accumulations of 5 to 10 inches, except 10 to 18
  inches west of Highway 89, are expected. For Wednesday night
  through Thursday: 2 to 4 feet possible above 7000 feet. Below
  7000 feet, 8 to 18 inches, possibly as much as 15 to 30 inches
  if precipitation remains all snow.

* WHERE...Greater Lake Tahoe Area.

* WHEN...For the Winter Weather Advisory, from 4 PM Tuesday to 4
  PM PST Wednesday. For the Winter Storm Watch, from late
  Wednesday afternoon through late Thursday night.

* ADDITIONAL DETAILS...Travel could be very difficult to
  impossible later Wednesday through Thursday with periods of
  white out conditions possible, especially in the higher
  elevations.

6-10 day temperature outlook. Image: NOAA

Winter Storm Watch for Mammoth:

URGENT - WINTER WEATHER MESSAGE
National Weather Service Reno NV
426 AM PST Tue Jan 15 2019

Mono County-
Including the cities of Bridgeport, Coleville, and Mammoth Lakes
426 AM PST Tue Jan 15 2019

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 4 PM THIS
AFTERNOON TO 4 PM PST WEDNESDAY...
...WINTER STORM WATCH REMAINS IN EFFECT FROM WEDNESDAY AFTERNOON
THROUGH LATE THURSDAY NIGHT...

* CHANGES...Increased snowfall amounts for tonight.

* WHAT...Tuesday-Wednesday: Moderate snow with accumulations of up
  to 4 inches east of Highway 395 and 6 to 18 inches west of
  Highway 395 above 7000 feet, are expected. Wednesday night
  through Thursday: 2 to 4 feet possible west of Highway 395 above
  7000 feet, with 10 to 20 inches elsewhere above 7000 feet.
  Between 6000 and 7000 feet, up to 6 inches is possible.

* WHERE...Mono County.

* WHEN...For the Winter Weather Advisory, from 4 PM Tuesday to 4
  PM PST Wednesday. For the Winter Storm Watch, from late Wednesday
  afternoon through late Thursday night.

* ADDITIONAL DETAILS...Travel could be very difficult to
  impossible Wednesday and Thursday with white out conditions
  possible.