Weather Service Report

FXUS66 KSTO 230627

1027 PM PST Sat Nov 22 2014

Clearing skies and abundant surface moisture will cause dense fog
overnight through early Sunday morning. High pressure will build
back in late Sunday and much of next week.


.Discussion... Dense fog with widespread visibility below 1/4
mile has developed over the central and southern Sacramento
valley. This is a challenging forecast since north winds are
expected to gradually increase overnight and the degree to which
this erodes the fog is in question. Since widespread dense fog has
already develop have issued a dense fog advisory for much of the
central and southern Sacramento valley. Have updated the forecast
to reflect current foggy conditions. Will take advisory through 10
am as north winds should sufficiently mix out surface moisture by
that time.

.Previous Discussion (Today through Tuesday)... Frontal system
has moved through Northern California. Behind the front showers
will be possible through the afternoon hours especially for the
mountains. Snow levels continue to be very high close to 8500 feet
but will start to lower as colder air advects into the region
through the afternoon. Not much in the way of snow accumulations
with this system with only a few inches expected for the higher
peaks. Patchy fog for the mountains tonight especially through
this evening and patchy fog developing over the southern CWA
valley area later tonight.

Lingering showers will be ending early in the evening. High
pressure will then begin to build over the region for Sunday 
and Monday. Northerly winds will develop the next couple of days
but nothing of significance in terms of wind speed. In the 
overnight hours northerly winds in the valley may prevent fog from
forming over the western side of the valley and limit any
formation to the southern eastern side of the valley. The ridge
builds in stronger through the first part of next week with warmer

.Extended Discussion (Wednesday through Saturday)

Models similar in depicting strong upper ridge centered over
Interior NorCal Wednesday morning, then shifting axis into the
Great Basin late Wednesday into Thursday as next upstream Pacific
storm approaches. Timing with this system is getting better
with models introducing leading edge of precip into western
portions of the CWA late Friday morning, spreading over most of
the forecast area Friday afternoon into night and continuing
Saturday. At this time, snow levels look to be around 6000 feet or
higher Fri/Sat. Significant model differences in QPF exist at this
time, as expected, with the 12z oper GFS showing much greater
storm total precip than the 12z ECMWF-HiRes.



Areas of dense Fog through Sunday morning with a mix of
LIFR/IFR/MVFR conditions. Northerly winds will improve vis by
mid/late Sunday morning.


.STO Watches/Warnings/Advisories...
dense fog advisory until 10 am pst sunday carquinez strait and 
delta...central sacramento valley...motherlode...northeast 
foothills/sacramento valley...northern san joaquin valley...
southern sacramento valley.



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Western Regional Climate Center,