Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 201100
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
400 AM PDT Sun Aug 20 2017


.SYNOPSIS...
Temperatures near to slightly above normal through the upcoming
week. Afternoon showers and thunderstorms possible over the
mountains through Wednesday.

&&

.DISCUSSION...
Upper troughing digging over Interior NorCal is helping to deepen
584 DM upper low off the SoCal coast. Low forecast to be
quasistationary through Tuesday before progged to open to trough
and move inland Wednesday. Synoptic cooling and onshore flow will
result in a cooling trend over the next several days with highs by
Tuesday in the upper 80s to 90s in the Central Valley, with 60s to
80s for the mountains and foothills. Northerly wind over northern
portions of the CWA today will make for some hazy skies as it
draws smoke southward from numerous Oregon wild fires. Instability
and moisture convergence over the higher elevations of the Sierra
Nevada and mountains of Western Plumas will result in afternoon
thunderstorms again.

Upper low off the SoCal coast will continue to draw moisture
northward into the area over the next several days leading to a
more widespread threat of deep moist convection, mainly over the
mountains and in the afternoon to evening hours. Tuesday into
Tuesday night looks to be the most active period for mountain
storms. Slight chance of showers and thunderstorms continues over
the higher terrain Wednesday, as temperatures edge up a few
degrees.

BTW, Skies should be mostly clear for Monday`s eclipse viewing,
however haze/smoke may come into play for northern portions of
the CWA.

PCH

&&

.EXTENDED DISCUSSION (Thursday THROUGH Sunday)

Medium range models showing broad troughing aloft continuing over
the forecast area Thursday into Friday then height rising over the
weekend. Drier weather expected with a gradual warming trend.
Temperatures forecast to be around 2 to 6 degrees above normal by
the end of the forecast period.


&&

.AVIATION...
Genly VFR conds ovr Intr NorCal nxt 24 hrs exc lcl MVFR/IFR poss
in ST vcnty of Delta til arnd 17z. Also, lcl MVFR poss in HZ/FU
vcnty KRBL Nwd. Isold to sct tstm poss ovr hyr trrn of Siernev
and mtns of Wrn Plumas Cnty btwn 21z-01z. SWly sfc wnd gsts up to
30 kts poss thru Delta til 16z and aft 23z.

&&

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

$$



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