Area Forecast Discussion
Issued by NWS Sacramento, CA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS66 KSTO 221725

925 AM PST Mon Dec 22 2014

Dry through Tuesday under high pressure ridge. Patchy late night
and morning valley fog. Another weather system will brush across
the region late Wednesday and early Christmas Day.


Expansive area of valley fog stretched from just south of Redding
to Modesto this morning and is clearly evident on visible
satellite. Visibilities have improved over past couple hours and
fog deck has lifted into stratus in most locations. Expect this to
break up throughout the day with sunshine returning. Otherwise,
forecast for today still on track with dry conditions and mild
temperatures. Will be looking at latest details for Christmas
Eve/Christmas precip for afternoon forecast package. CEO

.Previous Discussion...
Amplifying upper ridge over the eastern Pacific has finally pushed
the deeper moisture and warm advection north of the region. Skies
have cleared out across the region except for lingering clouds
across the northern mountains, and the solid footprint of stratus
and patchy fog over the Central Valley. Early morning temperatures
remain very mild ranging from the upper 30s and 40s in the
mountains to the 50s in the valley, about the same as 24 hours ago.

Dry and mild weather will continue for interior NorCal early this
week. Appears there will be enough northerly flow and mixing today
to break out of the stratus across most of the valley by late
morning or early afternoon allowing a return of sunshine for at
least a part of the day. Looks favorable for the pattern to repeat
itself tonight and early Tuesday, then there`s a chance the valley
stratus may develop Tuesday night and linger all day Wednesday as
flow begins to reverse ahead of the next system.

Confidence is increasing that we`ll see a quick moving system
brush across the region later Wednesday into early Christmas. Main
impacts will likely be confined to the mountains where 3-6 inches
of snow may fall Christmas Eve into Christmas morning. For the
valley, only light amounts of QPF (< 1/4 inch) are expected.

Northwesterly flow behind the system forecast to bring a return of
drier conditions for most of the area by Christmas afternoon.


.Extended Discussion (Friday through Monday)

Pacific ridging spreads eastward as trough shifts eastward of the
region. Dry northwest flow sets up, with breezy north-northeast
winds develop on Friday. Cooler temperatures set in, especially in the
mountains. The winds in the Valley will keep temperatures from
dropping too much.
An inside slider system will bring the potential for mainly
mountain precipitation for the weekend, along with another round
of breezy northerly winds. The ECMWF continues to be the wettest
of the extended models. Have bumped up pops for the northern
mountains and Sierra. This could be a rather cold system, but expect
that it will have little moisture to work with, so any rain and
snow amounts would likely be limited. EK



Fog lifted to stratus this morning with visibilities improving.
MVFR/IFR cigs remain in east Valley locations south of KRDD but
expect most locations to improve to VFR by around 20Z. BR and fog
return tonight, but again northerly winds will limit development,
which should be favored in sheltered areas east side of Valley. EK/CEO


.STO Watches/Warnings/Advisories...

$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.