Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 241048
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
248 AM PST Sat Jan 24 2015

.Synopsis...
Dry weather forecast with areas of night and morning valley low
clouds and fog through Monday. Temperatures expected to remain
well above normal through early next week in fog free areas.
Light precipitation is possible Tue and Wed next week.

&&

.Discussion...
A strong upper level ridge is centered over the eastern Pacific
and shifting eastward toward California. Skies are mostly clear
across the area, except for the persistent low clouds and fog that
is covering much of the Central Valley from Chico to south of
Fresno. This fog is locally dense in spots, and a dense fog
advisory will continue through late this morning for those
locations. We are seeing some locally breezy north/east winds over
the mountains, but they are of relatively little impact.

As high pressure builds into the area, locations that remain fog-
free (Northern Sacramento Valley, mountain locations) will be
experiencing unseasonably warm conditions this weekend. NAEFS
ensembles show that the Northern Sac Valley in particular will see
highly anomalous temperatures...they could be within a degree or
two of high records. Farther south...the fog will again be slow to
erode, with some locations not clearing out until the afternoon
today (if at all). From about Yuba City southward, highs will
remain around or below 60 degrees today, and perhaps a bit warmer
Sunday.

The upper ridge shifts east of California on Monday, with some
synoptic cooling expected that day. We should also begin to see
increasing high cloud cover later on in the day as a system off
the Baja California coast moves northward.

Computer models are finally coming into better agreement on the
track and timing of this system. Looks like some precipitation
will be possible along the Sierra beginning late Monday and
spreading northward on Tuesday. Snow levels are currently expected
to be around 6000-7000 ft, but only minor snow accumulations are
expected. The Valley has lower odds of seeing precipitation, but
can`t completely rule out a sprinkle or light shower.

Dang

&&

.Extended Discussion (Wednesday through Saturday)

Remnants of weak upper low forecast to move out of Southern
California early next week forecast to be somewhere over the
northern Great Basin by early Wednesday. This will bring a slight
threat of light showers to the northern mountains and Sierra
Cascade range but this threat will end quickly as high pressure
pushes back northward over the west coast. Despite variable cloud
cover on Wednesday, daytime highs are expected to remain a few
to several degrees above normal under warm airmass under the
ridge. Extended models show another upper low setting up off the
Baja coast by Thursday similar to the system forecast for earlier
in the week. This system would likely begin spreading high
cloudiness over the north state as early as Thursday but daytime
highs still likely to climb a bit under upper ridge and light
northerly winds. The upper low off Baja is forecast to slowly
shift inland Friday and Saturday remaining over Socal and the
southwest U.S but may be able to spread a few very light showers
northward up the Sierra as far north as Tahoe. The rest of the
forecast area will see variable high cloudiness going into next
weekend with daytime highs remaining well above normal under
upper ridging along the west coast.


&&

.Aviation...

Valley Low clouds/fog south of about KCIC with IFR/LIFR
conditions expected through about 19z then Conditions gradually
improving. Low clouds/Fog returning to the same areas after 06z
tonight. Elsewhere...VFR. Light winds foggy areas...otherwise
north to east winds 5 to 15 knots with gusts to 25 knots over
Sierra.


&&

.STO Watches/Warnings/Advisories...
dense fog advisory until 11 am pst this morning carquinez strait
and delta...central sacramento valley...northern san joaquin
valley...southern sacramento valley.

&&

$$








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