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Area forecast discussion 
National Weather Service Sacramento California
326 am PST Fri Jan 30 2015

Synopsis...
dry weather expected through the weekend with night and morning
valley fog and above normal temperatures. Some breezy north wind
today into Saturday. A slight chance of showers northern areas
Monday and Tuesday...otherwise mostly dry weather likely to continue
through mid week. A chance of precipitation much of northern
California the end of next week.

&&

Discussion...
axis of weak trough now over California has shifted east of the
forecast area and should now be of little impact other than some
scattered clouds over the Sierra. Otherwise skies are clear this
morning as upper level high pressure begins pushing back inland.
Northerly surface gradient starting to develop over far norcal as
surface high pressure system over the Pacific northwest shifts
southward. Light north winds over the northern Sacramento Valley
keeping North Valley fog free. The rest of the valley is seeing
lighter winds this morning and as a result...patchy fog has
developed from about Sacramento southward. Fog has not become
significant yet but will need to watch for denser fog formation as
dense fog has formed just to the south of the County Warning Area. Surface
gradient tightens this afternoon for breezy north to east winds
across most of the forecast area. At this time it appears
wind speeds will remain below advisory criteria. North to east
surface gradient maxes out across norcal tonight with good upper
level support. Therefore...expect breezy to gusty north to east
winds to continue through the night although decoupling will bring
some decrease in winds some valley locations. Should keep enough
wind in the valley however to keep overnight valley fog to a
minimum. Winds drop off quickly on Saturday as upper level high
pressure ridge pushes inland and gradients relax. Overall airmass
warms under the ridge on Saturday so should see warmer daytime
highs most areas with close to record for the date high
temperatures expected.

Lighter winds Sunday morning will allow valley fog to push
northward again although light north winds will minimize fog
chances for the northern Sacramento Valley. A shortwave trough
riding over the West Coast ridge and into the Pacific northwest
will bring cloud cover to most of the County Warning Area during the day on
Sunday. Cloud cover and cooler airmass will bring cooler daytime
temperatures on Sunday. The tail end of this trough will bring a
slight threat of showers over Shasta County Sunday night and
Monday. Cloud cover will bring a bit more cooling elsewhere
although daytime highs will remain well above normal.

&&

Extended discussion (tuesday through friday)

The ridge is flatten enough Tuesday to potentially allow the
southern periphery of a trough to bring a slight chance of light
rain to Shasta County. But that's as far south as the rain
extends. The dominant ridge builds back up over the West Coast
Wednesday, keeping the area dry.

However, a broad, deep upper trough is taking shape over the
eastern Pacific. The models show promising signs of the upper ridge
shifting into inter-mountain west, allowing the trough to creep
closer to the coast with increased chances of much needed
precipitation late Thursday through Friday. This system is
looking like an atmospheric river (ar) event, but the main swath of
moisture still looks to remain just north of our forecast area on
Friday, across northwest California and western Oregon. We need
the ridge to continue to shift east to allow the Arkansas to settle over
California. Jclapp

&&

Aviation...

Expect some patchy dense fog to develop this morning, most likely
around ksck but also possible near Sacramento taf sites.

North winds will increase to 5-15 kt by late morning/early
afternoon, spreading from north to south down the valley. Local
gusts up to 25 kt will be possible along the northern and western
Sacramento Valley after 20z. Jclapp



&&

Sto watches/warnings/advisories...
none.
&&

$$

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