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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Monday
• 
• High: 23 °
• Low: 20 °
• Snow Showers

• Tuesday
• 
• High: 31 °
• Low: 22 °
• Chance of Snow

• Wednesday
• 
• High: 31 °
• Low: 25 °
• Chance of Snow

• Thursday
• 
• High: 43 °
• Low: 29 °
• Partly Cloudy

• Friday
• 
• High: 41 °
• Low: 29 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Sacramento California 
901 PM PST sun Feb 12 2012 


Short term discussion... 
from infrared satellite imagery it appears back edge of Pacific frontal 
system now just off the coast with prefrontal precipitation now 
inland as far as the west slopes of the Sierra Nevada. 00z NAM 
running a little slow by at least a few hours as were previous 
models. With Blue Canyon ASOS and Sierra web cams showing snow 
already falling...have moved up start time of Winter Weather 
Advisory. So far precipitation amounts have been fairly light 
ranging from about .15 inches over Shasta County to around a few 
hundredths elsewhere. Snow levels in current forecast package appear 
okay. Upper low is forecast to drop southeastward tonight and Monday 
with the center expected to reach south of the Tahoe area by ooz 
Tuesday. Enough moisture and instability expected Monday afternoon 
for scattered showers but instability does not appear strong enough 
for thunderstorm activity. Precipitation should drop off quickly Monday 
afternoon under upper level north to northeast flow and may be able 
to drop Winter Weather Advisory early. 


Skies should begin to clear Monday night. Although a light northerly 
surface gradient should keep fog from forming over the northern 
Sacramento Valley...lighter winds and residual moisture will bring a 
chance of fog over the southern Sacramento and northern San Joaquin 
valleys Tuesday morning. A warming airmass and clearing skies under 
upper level high pressure will bring warming all areas on Tuesday 
afternoon. 


A secondary shortwave low dropping out of the Gulf of Alaska is 
forecast to drop into the Pacific northwest Tuesday evening. Models 
have really been struggling with track of this system bouncing it 
around from an inside slider dropping east of the County Warning Area keeping all 
but the Sierra dry Wednesday to a trough digging into norcal 
bringing another round of precipitation to the north state. Grids currently 
carrying close to climatology probability of precipitation which considering great variability in 
models probably best idea for now. Models in better agreement for 
the end of the week bringing ridging and dry conditions Thursday. 


Seems to be some consistency in the models towards the end of this 
week with a closed low forecast over the eastern Pacific by late 
Friday. European model (ecmwf) brings precipitation to the north state as early as Friday 
afternoon while GFS holds off until Saturday. Needless to 
say...forecast confidence in extended forecast period remains low. 
Either way...long wave ridging over the West Coast should preclude 
any significantly heavy precipitation events through the next 10 days. 


&& 


Aviation... 
Pacific frontal system will move through interior norcal overnight into Monday. For northern 
interior/coastal mountains and Central Valley...widespread MVFR/IFR conds with isolated LIFR 
through about 18z Monday then impvg conds Monday afternoon. Over Sierra Nevada...widespread 
MVFR/IFR conds with local LIFR through 00z Tuesday then impvg conds. Snow levels 
030-040. 


&& 


Sto watches/warnings/advisories... 
Winter Weather Advisory through 4 PM PST Monday above 4000 feet for 
the West Slope northern Sierra Nevada...western Plumas County/Lassen 
park. 


&& 


$$