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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Monday
• 
• High: 54 °
• Low: 38 °
• Rain Showers

• Tuesday
• 
• High: 56 °
• Low: 40 °
• Partly Cloudy

• Wednesday
• 
• High: 56 °
• Low: 38 °
• Partly Cloudy

• Thursday
• 
• High: 63 °
• Low: 40 °
• Partly Cloudy

• Friday
• 
• High: 56 °
• Low: 41 °
• Chance of Rain

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


Short term discussion... 


Ridge of high pressure weakening over the area with an upper level 
trough approaching. Temperatures this afternoon are running 
similar to yesterday. Visibilities increased from the morning fog 
along the east side of the valley and around Sacramento between 10 
and 11 am then low clouds remained over Sacramento and Marysville 
area until around 2 PM this afternoon. Middle and high clouds are 
pouring into the area this afternoon ahead of the approaching 
system. 


This system is expected to be colder and wetter than the most 
recent systems but will quickly move through northern California 
tonight into Monday. Precipitation is expected to commence in the 
coastal range around sunset and spread southeast across all of 
interior northern California around midnight. Moderate to heavy 
precipitation is possible later this evening and early Monday as 
the front moves onshore followed by showers through much of Monday 
in the cold unstable airmass behind the front. Quantitative precipitation forecast amounts of 
around 1/4 to 1/2 inch in the valley and the coastal range 
including Lake County...around 1/2 to 3/4 inch in Shasta County 
and around an inch in the Sierra and western Plumas County. Snow 
levels will lower significantly behind the front...to around 3000 
to 3500 feet Monday. Little snow accumulation is possible around 
3000 feet. Winter Weather Advisory for zones 68 and 69 looks good 
with up to a foot of snow accumulation above 5500 feet and up to 6 
inches around 4000 feet by Monday afternoon. 


Monday morning commuters should be prepared for winter driving 
conditions and allow extra time to reach their destination with 
rain and snow over the area. Precipitation is expected to taper 
off in the northwest in the late afternoon but lingering showers 
in the southeast into Monday evening as the system moves towards 
the Desert Southwest. Temperatures will be cool on Monday with 
temperatures dropping down (about 5 to 10 degrees) to around the 
middle 50s in the valley and 20s to middle 30s in the mountains. The low 
moves off to the Desert Southwest by Tuesday morning bringing 
drier conditions except possible lingering showers over the 
Sierra. Tuesday morning may be chilly with areas of clearing skies 
and cold air mass over the region. Valley fog may also develop 
Tuesday morning with some clearing of the skies and recent rain 
and light winds...especially along the east side of the valley. 


There is still some variability with the track and timing of the 
next weaker system but at least the 12z models today are in a 
little better agreement with a further west track of the next 
system Tuesday night. The 12z European model (ecmwf) came in with a track further 
west closer to the 12z GFS but then the 18z GFS had the wave 
farther to the east and slower closer to the 00z European model (ecmwf) with only a 
slight threat possible for the Sierra Wednesday. The further west 
track of the 12z GFS and ec would bring a threat of precipitation 
to interior northern California compared to the dry NAM and Gem. 
The current forecast leans toward the 12z GFS and ec with a chance of 
precipitation Tuesday night into early Wednesday and showers 
lingering over the Sierra into the afternoon but may change with 
the track and timing of the next system. 
&& 


Extended discussion (thursday through sunday) 


Quiet weather is expected later this week as weak ridging develops 
along the West Coast within mean northwest flow aloft. This will 
lead to dry and pleasant weather Thursday and at least part of Friday 
with temperatures near to several degrees above normal. All three 
extended models are indicating a deep closed low in the epac 
moving onshore to the Pacific northwest and norcal at some point Friday or 
Sat...though details vary. Have not made any substantial changes 
to previous forecast...other than slightly higher probability of precipitation next 
weekend given model agreement on an unsettled pattern. -Dvc 


&& 


Aviation... 


Pacific frontal system will move through interior norcal tonight through Monday. For Central Valley... 
incrsg MVFR/IFR conds spreading from north to S tonight becoming wdsrpd after 07z through 
18z Monday then impvg conds Monday afternoon. For northern interior/coastal mountains...widespread 
MVFR/IFR and isolated LIFR in precipitation through 18z Monday then impvg conds Monday 
afternoon. Over Sierra Nevada...incrsg MVFR/IFR conds tonight becoming wdsrpd after 08z 
with local LIFR through 00z Tuesday. Snow levels 030-045. 


&& 


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


&& 


$$