Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 202332

332 PM PST Thu Nov 20 2014

Weather systems continue to move through NorCal into Saturday
bringing periods of precipitation. The second system is expected
to be the wettest Friday night into Saturday. High pressure builds
over the area next week for generally dry weather and milder
daytime temperatures along with areas of morning valley fog.


.Discussion... Rain band progressing east through NorCal late
this afternoon. Band will shift east over the Sierra by
sunset...with activity becoming more showery in nature. Snow
levels are currently above 6000 feet and expect them to fall to
5000 feet during the evening hours. 1 to 2 inches of snow is
expected near pass level. Highways over the Sierra will likely
become icy above 5000 feet after sunset...up to 4 inches could
fall over the highest peaks. Rainfall amounts for the valleys
should be in the 0.20-0.50 range.

Breaks in the cloudiness or clearing is looking more likely after
midnight which will lead to patchy fog or dense fog...especially
over the southern Sacramento and San Joaquin valleys.

The next system which is more of a plume of moisture embedded in
strong jet stream energy will streak across NorCal late Friday
night and Saturday. This system has the deeper moisture with Pwat
values 1.00-1.50 inches. Rainfall amounts will range from .10-.50
for valleys and 0.75-1.50 inches for the mountains. Snow levels
will be high with this warm system starting around 6500 feet...but
rising to 7500 feet through Saturday night. Only an inch or two of
snow will fall at highest elevations.

Ridging and northwest flow will develop on Sunday with drying
conditions. temperatures will remain near normal.

.Extended Discussion (Monday through Thursday)

Dry conditions expected early next week as upper level ridging
builds over the area. Temperatures are tricky, as lingering
moisture and clearing skies with light wind will allow for fog to
develop at times.

Mid to late next week has become a little more consistent, with the
ECMWF backing off from earlier suggestions of a trough passing
through on Wednesday. This is more in line with the GFS and GEM
models, so have trended drier with forecast. This makes sense as
ridge will probably be slow to break down. EK



A mix of LIFR/IFR/MVFR early this morning with ceilings and
visibilities after yesterday`s weather system. A second wave of
weather will spread precip into interior Norcal after 15Z Thu and
spread SEwd into the I-80 corridor after 18Z Thu. Widespread
MVFR with local IFR cigs/vsbys spreading across NorCal.


.STO Watches/Warnings/Advisories...

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