Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
958 PM PST sun Dec 21 2014
dry through Tuesday under high pressure ridge with patchy fog.
There is a chance another system may affect the region Wednesday
into early Christmas day.
patchy fog beginning to form over the area this evening.
Although...just enough winds have continued along with a few
patches of clouds to keep the fog from becoming widespread. Fog
will be densest overnight where winds diminish and skies clear.
North winds will increase after 10 am Monday. This will likely mix
out the fog by noon with sunny skies possible during the
afternoon. Current forecast handles this well and no evening
update will be needed.
moisture will continue to stream into the region this evening
but generally any lingering showers will be in the mountains
through tonight. Overcast skies overnight might limit the amount
of valley fog around Sacramento but skies may start to clear
enough by morning where fog may start forming. Some fog is still
being reported in the foothills and mountains and will likely
continue to have some overnight.
A strong ridge of high pressure builds over the interior to keep
the interior dry for Monday and Tuesday. Fog continues to look
like it may become an issue each night and morning starting Monday
morning. The thicker fog for Monday may be limited to the
San Joaquin Valley. Tuesday the fog should expand further north
into the Sacramento region.
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
On Wednesday a system will approach the region but most models
keep the interior dry except for the far northwest part of the
state. Wednesday night as the system passes through continues to
look like the best chance of any precipitation.
Extended discussion (thursday through sunday)
Drier northwesterly flow will move over the area in the wake of
the Christmas eve system heading into next weekend. This could
bring a period of breezy north winds to the forecast area, along
with colder overnight temperatures. The European model (ecmwf) and Gem are hinting
at another inside slider system early next week, whereas the GFS
is dry. With low confidence in the forecast, our forecast closely
resembles climatology for early next week.
Expect most locations to again deteriorate to IFR/MVFR with local
LIFR this evening and tonight as fog develops. Expect most
locations to improve to VFR/MVFR by 18-20z Monday.