Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 290429
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
929 PM PDT WED SEP 28 2016

.SYNOPSIS...
Cooling to below normal Friday and 15 to 25 degrees below normal
by Sunday. Chance of showers and isolated thunderstorms Sunday
into Monday with snow showers over higher terrain. Drier with
some warming Tuesday into Wednesday.

&&

.DISCUSSION...
Delta breeze is much stronger this evening and the Sacramento
region is cooling off much faster than the last several nights.
By morning the valley will cool into the 50s. The delta breeze
will stay up on Thursday and greater cooling over the interior is
expected than today.

A trough will gradually deepen the next few days to bring a
strong cooling trend to the region through Saturday. The delta
breeze will be stronger each of the next several days to help with
cooling as well as synoptic cooling that will occur each day from
the trough. Significant cooling will occur by Friday to lower
temperatures into the 70s in the valley to the 60s to mid 70s for
the mountains. Winds will also increase across the valley and
mountains the next couple of days.

Continued cooling is expected as the trough deepens Friday night
and Saturday. Conditions are expected to remain dry though this
period with continued breezy conditions for most areas and windy
conditions over the ridgetops.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)


An active weather pattern is expected for the long term forecast
period for northern California. Cooler temperatures will be felt
on Sunday as a trough of low pressure begins to come onshore from
the Pacific with increased chances for showers and slight chances
for thunderstorms through Sunday evening. Both GFS and ECMWF
models are in good agreement with placing surface based and upper
level instability across the coastal mountains and the central
valley south of Redding, and increased moisture within forecast
profiles would indicate good chances for rain. The cool system
will bring snow levels down to around 5000 feet, so higher
elevations could see some snow accumulations affecting mountain
travel Sunday afternoon through early Monday morning.

The main trough base will swing through the forecast area by early
Monday morning, and thunderstorm chances will diminish. However,
chances for showers will continue to linger behind the passage of
the system as upper level spin continues to give a chance for rain
showers through Tuesday evening. High temperatures will warm up a
bit to allow snow levels to rise on Monday and Tuesday, so
chances for higher elevations to see additional snow on Tuesday is
minimal at this time.
&&

.AVIATION...

VFR conditions expected at the terminals for the next 24 hours.
Expecting mainly southerly flow below 10 kts, except for gusts up
to 30 kts for the delta and Sierra ridgetops. Local gusts up to 20
kts in the northern Sacramento valley also possible Thursday
afternoon.
&&

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

$$


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