Weather Service Report


576 
FXUS66 KSTO 292222
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
322 PM PDT FRI APR 29 2016

.Synopsis...
A chance of showers over the Sierra this evening through Saturday,
with light snow accumulations. Thunderstorms possible over the
Sierra Sunday afternoon and evening. Breezy north winds developing
this evening through Saturday. Above normal daytime temperatures
through mid week. Cooler with showers and thunderstorms possible
next Thursday and Friday.

&&

.Discussion...
High pressure ridging today will give way as an upper level shortwave
with a surface cold front moves southward. Moisture is limited,
BUT some showers have begun developing over Shasta County and into
the Sierra. A few thunderstorms could pop up in those areas into
this evening, so have added them to the forecast. The Sierra
south of I80 could see around an inch of snow at and above pass
levels. 

Dry, warm, and sunny weather is expected on Saturday, except for a
few lingering showers over the Sierra crest south of Highway 50.

The main issue tonight and Saturday is wind. Winds will be shifting
to the north by this evening. Surface high pressure will build
over Oregon, with the pressure gradient tightening and winds
increasing. Winds will increase tonight and become breezy, with
windy conditions on Saturday, especially on the west side of the
Valley and over the Coastal Range. A Wind Advisory remains in
effect from 11 pm tonight to 5 pm Saturday.

Another disturbance drops down Sunday, and this will bring the
potential for mountain showers and thunderstorms in the afternoon
and evening. Some breezy north to east winds continue, but will be
quite a bit weaker than the Saturday winds. Highs in the Valley
should peak into mid 80s. EK

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

A cooling trend with unsettled/showery weather developing for the
EFP as the synoptic pattern is dominated by a digging offshore trof
and increasing onshore flow. Model consensus suggests the closed
upper low will slide into Socal by/around Fri. 

Near normal max temps Tue/Wed are forecast to cool several degrees
below normal Thu/Fri especially over the Srn portion of our CWA...
which is closer to the core of the upper low over Socal. Synoptic
pattern suggests chance of showers increases during the EFP as
cyclonic flow increases over Norcal. Possible T-storms mainly
over the mtns Thu/Fri as instability increases over our CWA.  JHM

&&
&&

.AVIATION...

VFR conditions over interior Norcal thru 06z Sat except for 
BKN-OVC AOA 200-250 moving SEwd over the area through 21z Fri. 
Upper air feature moves over Norcal tonite and Sat bringing 
strong Nly winds and local MVFR/IFR conditions in -SHRA/SHSN to
the Shasta Co mtns and Siernev. Nly barrier jet winds forecast to
develop on the W side of the Valley with areas 25g40kts 06z-18z
Sat and local NE-E g45 kts winds over Siernev.


&&

.STO Watches/Warnings/Advisories...
Wind Advisory from 11 PM this evening to 5 PM PDT Saturday for 
Carquinez Strait and Delta-Central Sacramento Valley-Clear 
Lake/Southern Lake County-Mountains Southwestern Shasta County 
to Northern Lake County-Northern Sacramento Valley-Northern San 
Joaquin Valley-Southern Sacramento Valley.

&&

$$

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Western Regional Climate Center, wrcc@dri.edu