Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 220503

1003 PM PDT Sun Sep 21 2014

Dry and warmer temperatures for the early week. Cooler and
possibly wetter weather expected for the middle to end of the


Upper low has shifted east into Nevada this evening. Dry air is
filtering into Norcal behind this system and skies have turned
clear. Have updated forecast for mostly clear skies over night.
Moderate push through the delta with temperatures running 5-10
degrees cooler versus 24 hours ago. Otherwise forecast is on

.Previous Discussion... A cooler day today with temperatures
about 5 to 10 degrees lower than yesterday. This was brought by a
cool upper level low along with quite a few clouds. The low has
shifted into Nevada with the potential for showers and isolated
thunderstorms mainly limited to the higher Sierra and mountains of
western Plumas County for early this evening.

Clearing skies expected tonight as upper level ridging begins to
build in. the low continues eastward. Slightly cooler overnight
lows expected along with a decent Delta breeze. The ridging will
bring fair skies and warmer temperatures on Monday, with
seasonable highs.

The ridge will quickly shift quickly eastward by late Monday/Tuesday as a
low pressure system in the Pacific approaches the coast. Daytime
temperatures Tuesday will be similar to Monday before a cooling
trend begins Wednesday. Models still in good agreement with a cool
trough and Pacific frontal system moving onshore early Wednesday.
Some precipitation is expected to spread into the western forecast
area late Tuesday night into early Wednesday, then spread across
the rest of the area by Wednesday night. Rain amounts are not
expected to be high and should be greatest for the Coastal Range. EK

.Extended Discussion (Thursday through Sunday)

Upper level trough along the west coast will move into Northern
California on Thursday bringing cooler temperatures and a chance
of precipitation. Temperatures will be in the 70s in the Valley
and 50s and 60s in the mountains on Thursday and Friday. These
temperatures are around 6 to 12 degrees below normal for this time
of year. Temperatures may warm up over the weekend but how much
depends on how quickly the trough moves to the east.

Precipitation is expected to spread over interior
Northern California on Thursday with the best chance north of
Interstate 80. The models continue to vary with the strength,
track and timing of the trough for low confidence in when the
precipitation will end and coverage of precipitation. The GFS is
the fastest and weaker with the trough and the ECMWF the slowest
and forming a closed low over Northern California. The forecast
leans towards the ECMWF with precipitation possibly lingering into
next weekend especially over the mountains.



Generally VFR conditions next 24 hrs except local MVFR/IFR
conditions due to smoke around King Fire including KGOO. Gusts to
30 kts through the delta overnight.


.STO Watches/Warnings/Advisories...

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