Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 210619
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1019 PM PST Sat Dec 20 2014

.Synopsis...
A few showers continue overnight mainly north, diminishing on
Sunday. Dry Monday and Tuesday under high pressure ridge. There is
a chance another system may impact the region Wednesday into
Christmas Day.

&&

.Discussion...
Weak system passing north of the area will bring scattered showers
to Shasta county and northern Coastal Range tonight...generally
dry elsewhere. May see some patchy fog if a few breaks in the
clouds occur for valleys. Current forecast is on track and no
evening update will be needed.

.Previous Discussion...
A weak warm front is moving through the region. The atmosphere is
very moist so there is a chance of showers. Any showers should be
light for most areas other than in the far north where there is a
greater chance of seeing some moderate rain. Snow levels will be
rising throughout the evening so expect them to remain above major
trans-sierra pass levels.

Moisture will continue to stream into the region through Sunday
evening before a strong ridge of high pressure builds over the
interior to keep things dry for several days. Fog may become an
issue each night and morning starting Monday morning.

Today`s chilly temperatures are actually around normal for us this
time of year. As the ridge builds expect most temperatures to warm
well above normal...10 to 15 degrees above normal. Redding could
be flirting with reaching 70 degrees on Tuesday. Further south in
the valley moist air and morning fog and a temperature inversion
may limit the amount of warm up. I expect adjacent foothills to
end up being warmer.


.Extended Discussion (Wednesday through Saturday)

Models continue to struggle with the evolution of the Christmas
Eve system, although they are in slightly better agreement than 12
hours ago. The ECMWF remains to be the most bullish, bringing
potentially moderate snow and modest Valley rain to the area. The
operational GFS brushes by the northeastern portion of the state,
bringing Lassen Park some light snow. The Parallel (Hi-Res) GFS is
a blend of the two. The GEM has the farthest north storm track and
would be dry altogether for NorCal. With a majority of models now
showing at least some precipitation, we`ve increased our PoP
forecast accordingly.

Drier northwesterly flow moves over the area in the wake of the
system heading into next weekend. This could bring colder
overnight temperatures.

Dang


&&

.Aviation...

Widespread IFR/MVFR conditions continue across Valley TAF sites as
abundant moisture remains over the region. IFR/LIFR conditions
will continue over the mountains. Patchy fog may develop across
parts of the Valley overnight. Snow levels 060-070 will rise to
above 080 by early Sunday. Light winds.


&&

.STO Watches/Warnings/Advisories...
None.
&&

$$






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