Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 261654
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
854 AM PST Mon Jan 26 2015

.Synopsis...
Dry weather with areas of night and morning valley low clouds and
fog today. Temperatures expected to remain well above normal today
in fog-free areas. Light precipitation is possible Tuesday and
Wednesday.

&&

.Discussion...
Areas of fog continue to meander over the southern sac/nrn San
Joaquin valleys this morning...with fluctuating vis between 1/4sm
and 5sm. High clouds will overspread the area this afternoon from
the south...as mid/high level moisture wraps around upper low west
of San Diego. Current forecast is on track and no morning update
will be needed.

.Previous Discussion...
High clouds ahead of the low off the Baja coast continue to spread
northward into NorCal. Valley stratus mixed out Sunday afternoon,
so likely to see more fog early this morning rather than low
clouds. Already seeing some patchy dense fog across portions of
the Central Valley, and it will become more widespread through the
valley around sunrise.

The strong upper ridge will continue shift east today resulting in
some synoptic cooling, but weakening offshore flow will also allow
a little further cooling in the foothills. Morning valley fog will
give way to mixed sun and clouds as profiler data indicate the
surface inversion is even more shallow than Sunday. Clouds will
begin to increase further late in the day as the Baja system
approaches.

This weather system will skirt by the area on Tuesday with its
main impact expected to be to our south over central California.
It is weak and is expected to have little effect on NorCal other
than bringing showers to the northern Sierra and a chance of
showers elsewhere. The northern Sierra will likely see some
accumulating snow along the crest. Parts of the valley may see a
sprinkle or light shower, but rainfall amounts will be sparse.

Showers may linger over the mountains through Tuesday night, with
dry weather expected to return for Wednesday and Thursday.

&&

.Extended Discussion (Friday through Monday)

Upper level trough over the desert southwest on Friday. This will
bring a slight chance of precipitation near the Sierra
Crest...mainly south of highway 50 on Friday. High pressure builds into
Northern California from the Eastern Pacific on Saturday and the
low retrogrades over Southern California and Mexico. This will
bring dry weather on Saturday. North to East winds are expected
Friday into early Saturday as surface high pressure builds into
the Pacific Northwest and into Nevada. Breezy and gusty North to
East winds are expected to weaken on Saturday afternoon as the
surface high shifts to the east.

Ridge flattens Sunday into Monday with the potential for some
disturbances moving through. The timing and track of these varies
with the models but they could bring a threat of precipitation.
Although for now, the forecast for interior Northern California on
Sunday and Monday is dry.

&&

.Aviation...

Areas of IFR/LIFR vis/ceilings in the Valley until around 19Z
then MVFR with local IFR visibilities in the afternoon then
decreasing overnight as weather moves north and mixes airmass on
Tue. Mid and high clouds spreading northward ahead of low pressure
system moving northeast into California with potential showers Tue
remaining over eastern valley and mtns.     JClapp


&&

.STO Watches/Warnings/Advisories...
None.
&&

$$







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