Area Forecast Discussion
Issued by NWS Sacramento, CA

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256
FXUS66 KSTO 051207
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
407 AM PST Mon Dec 5 2016


.SYNOPSIS...
A weather disturbance will bring a slight chance of showers to the
mountains thru Tuesday. A colder air mass associated with the
system will result in near to below freezing overnight
temperatures across the Central Valley tonight and Tuesday night.
A potentially stronger system will move into the region later this
week.

&&

.DISCUSSION...
Mostly clear to partly cloudy skies cover interior NorCal early
this morning as northwest flow continues. Some patches of fog
cover much of the Central Valley as winds are generally light and
dew points have inched up a bit in many areas. Temperatures are
rather chilly, in the upper teens and 20s in the colder mountain
areas and mainly 30s elsewhere.

Weak dry cold front is moving south through the region currently.
Northerly winds will pick up a bit through the Central Valley
today as the front moves south. This should end any remaining
valley fog during the morning.

Another shot of cooler air will move into the region tonight and
Tuesday as another weak system clips us as it drops down in
northwest flow. A few snow showers are expected in the mountains
before tapering off by early Tuesday evening. The main impact is
expected to be the coldest temperatures so far this season with
large parts of the Central Valley expected to see minimum
temperatures drop to around freezing tonight and Tuesday night.

The next more impactful system is expected beginning Wednesday
night and continuing through the end of the work week and has the
potential to bring a return of more widespread precipitation and
gusty southerly winds.

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)
Precipitation will continue interior northern California during
the day on Friday as a swath of decent precipitable water (PW)
values of 1.3 to 1.5 inches streams in over the Bay Area. Given
the amount of moisture this system brings along the Atmospheric
River, we could be looking at some heavy rainfall, especially for
the Sierra locations. Additionally, as indicated by the high PW
values, we expect this system to be warm with relatively high snow
levels of 5000ft up north to near 7000ft over Sierra Friday, and
lowering overnight.

By Friday night, the heaviest precipitation should be beyond us
as the jetstream and moisture tap shifts just south of the area
with post frontal showers continuing. Generally zonal flow should
continue for Saturday into Monday with a chance of light
precipitation remaining over the area.    JClapp/Wilson

&&

.AVIATION...
Areas of Valley MVFR and local IFR in BR/FG this morning. Light
northerly surface flow in nrn Sac Valley should keep RDD and RBL
fog above 1sm vis. Potential Valley IFR to LIFR fog again Wed
morning with some frost. JClapp

&&

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

&&

$$



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