Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 021801
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
955 AM PST Fri Dec 2 2016


.SYNOPSIS...
Breezy north winds continue today with winds decreasing on
Saturday. Morning low temperatures will be chilly, with warming
daytime temperatures into the weekend. Light showers and cooling
temperatures Sunday into Monday mainly north of Sacramento and
over the northern Sierra. Turning much colder Tuesday through mid
week. Valley minimum temperatures dropping to near freezing
Tuesday through Thursday. A chance of rain or mountain snow again
by the end of the week.

&&

.Short Term Discussion...
No changes in the short term with continued breezy Nly winds
today.

Latest guidance trending the Sun/Mon system farther N and a bit
slower and will be working on that for the afternoon package.
Uncertainty in the Mon nite/Tue period with the ECMWF trending
wetter for the Nrn and Ern portions of our CWA than the much
drier GFS. Regardless, QPF is light and not really impactful
for our CWA.  JHM

.Previous Discussion...
Breezy north winds today with surface gradient from MFR to SAC about
8 and 1/2 mb this morning. These winds have kept temperatures this
morning up a few to several degrees higher than 24 hours ago. Upper
ridging over the west coast will bring warmer temperatures today
with daytime temperatures climbing to a bit above normal for this
time of year. Surface high pressure forecast to drop into the Great
Basin tonight allowing the northerly surface gradient to decrease a
bit while easterly gradient over the Sierra keeps breezy winds going
there tonight. Lighter winds tonight may allow temperatures in the
valley to cool a bit tonight while a warming airmass allows mountain
temperatures to climb a bit. High pressure pushing in over the
southwest U.S. will bring some warming most areas Saturday under
mostly fair skies. Daytime highs Saturday will be the warmest of the
week and in some cases up to 10 degrees above normal. Surface
gradients drop off significantly Saturday night. Despite drop off in
winds...overnight lows should come in similar to Friday night lows
as airmass continues to warm under the ridge. Upper ridge begins to
flatten on Sunday as a shortwave trough off the Pacific pivots into
the Pacific Northwest. Impact for most areas will be cloud cover and
a significant drop in daytime highs although maximums will are still
expected to be a bit above normal. Areas north of about Chico will
also see a chance of light rain. An upper low dropping out of the
Gulf of Alaska will usher in much colder air into the region on
Monday as well as bring a chance of rain and mountain snow into the
northern portions of the CWA as well as the northern Sierra. Snow
levels will drop in the colder airmass with snow levels down to
around 3000 feet in Shasta county. Cloud cover and colder airmass
will bring daytime highs Monday down to several degrees below
normal.

&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)



A longwave trough of low pressure will rotate through the upper
CONUS and bring cooler conditions to northern California with some
chances for precipitation Tuesday. Light rain for the northern
portions of the Sacramento valley are possible with light snow for
the Sierra and northern mountains. Accumulations less than an
inch are expected at this time Tuesday for elevations higher than
1500 feet.

ECMWF and GFS models indicate different amplitudes in the upper
flow pattern Wednesday and Thursday, but the general consensus is
a shortwave ridge of high pressure will create dry weather
Wednesday for much of the forecast area. Differences in timing of
precipitation associated with the progression of the next upper
level disturbance create uncertainty of precipitation for the
latter end of next week, but the best chances for precipitation
look to be Thursday into Thursday night at this time. High and
low temperatures for the middle of next week will range between 5
and 10 degrees below normal for this time of year, with some
morning low temperatures at or below freezing.


&&

.AVIATION...


VFR conditions anticipated for the next 24 hour forecast period.
Gusty northerly winds for Valley terminals up to 25 kts today
through early evening hours with stronger gusts up to 40 kts over
the Sierra ridges.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$


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