Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 131154
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
354 AM PST Fri Jan 13 2017


.Synopsis...
Lingering showers over the Sierra this morning. Then mainly dry
conditions expected through Monday except a slight chance of light
showers coast range on Sunday. Next chance of precipitation next
Tuesday with heavy precipitation possible during the middle of
next week with renewed flooding concerns.
&&

.Discussion...
Upper low pressure system now centered along the Socal coast and
continuing southward. Dry northerly flow is currently developing
north of this low over the forecast area with cloud free skies
most areas. Still a few scattered clouds over the northern Sierra
as southeast flow aloft brings lingering moisture northward and
there still may be a few light showers there this morning. Other
weather concern this morning is fog forming in the central valley.
Light northerly breezes have kept fog from forming in the northern
Sacramento valley but farther south...abundant ground moisture
and mostly clear skies have allowed fog to form and areas of dense
fog appear likely. Upper ridging moving in across the north state
will bring fair skies and a slight warming this afternoon with
daytime highs near or slightly above normal. Fog will likely make
a repeat performance on Saturday morning under similar stable
conditions under the ridge. Models fairly consistent with each
other in dropping a weak low southward along the coast on Sunday.
Looks like only precipitation threat will be along the coast range
but ECMWF does bring precipitation farther inland. No matter
which solution pans out...precipitation will be quite light. Cloud
cover associated with this weak system might hinder fog formation
a bit Sunday morning but some valley fog still likely. Despite
the weak system Sunday...overall airmass continues to warm with
daytime highs expected to warm to a few to several degrees above
normal. Upper ridging keeps dry weather over the north state
Monday with another round of morning valley fog.

&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

Models still showing that another atmospheric river could be aimed
for the West Coast next week. Both the GFS and ECMWF indicate that
the moisture plume should start impacting NorCal sometime Tuesday.
Heavier and more widespread precipitation is forecast to begin by
Wednesday morning and continue through Thursday. Looks like
weather will become more showery on Friday, but another wave of
widespread precipitation would arrive Friday night into Saturday.
Snow levels would initially be high, above 7000 ft, then lower on
Thursday and Friday ranging 3000-4000 ft. Given the already high
river/creek stream levels, flooding will continue to be a concern.

JBB/Dang

&&

.AVIATION...

Areas of dense fog have developed early this morning from around
KMYV (Marysville) to the Sacramento region and southward to the
Stockton area. Expect improvements in visibilities and ceilings
around 19-20z. North winds will continue today ranging 5 to 15 kt
across Valley TAF sites. Patchy dense fog is likely to develop
again during Saturday early morning hours.

JBB

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this afternoon for Carquinez Strait
and Delta.

&&

$$



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