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600
FXUS66 KSTO 180536
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1035 PM PDT Fri Aug 17 2018

.SYNOPSIS...

Warming trend continues into the weekend with slightly cooler
temperatures early to mid next week. No precipitation is expected
but areas of smoke and or haze will continue.

&&

.DISCUSSION...
Update:  Smoke from the Mendo WF Complex began to spread a little to
the SSEwd late this afternoon/early evening in the wake of the upper
trof that has now passed E of our CWA. As upper level ridging builds
over the region on Sat, some of the smoke at the WFs will spread in
multiple directions instead of the primarily SW flow which we have
experienced with the trof passages the last couple of days. Winds at
the surface and at 925 mbs (~2 kft) will turn light N to NEly over
most of the fires, so we should begin to see some Wwd drift of smoke
until Sun, when the next Pac trof is forecast to near the Pac NW
coast late in the day. So hot, smoky, hazy conditions will prevail
over a large section of our CWA on Sat before there is some
improvement Sun/Mon as winds turn SWly with the approaching and.
passing upper trof.   JHM


An upper level trough will continue to track east through the PacNW
and this will allow for a ridge to build into NorCal today and
tomorrow bringing hot and dry conditions. Highs this afternoon will
generally run about 3-6 degrees warmer than yesterday. The ridge
will be centered over us on Saturday and that will bring the warmest
day to the area with highs near 100 in the southern part of the
valley and as warm as 104 up north. The ridge will also strengthen
the inversion and bring a bit more widespread haze. As we head into
Sunday a trough will push into the PacNW pushing our ridge to the
east. This will bring slightly cooler temperatures although they
will still remain on the warm side on Sunday. With the incoming
trough we will see increasing SW winds with the breeziest winds
expected in the Sierra.

That trough will then hang out on the west coast into early next
week. This will keep temperatures near average for this time of
year and somewhat higher elevation breezy winds will continue
into early next week. As the trough pushes in it will push monsoon
moisture well east and moisture associated with the trough will
remain north. This will keep conditions stable with no precip
expected.

-CJM

&&
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)

A short wave ridge will build in for the mid part of the week and
that will bring slightly warmer temperatures with them running a
few degrees above average. Long wave troughing moves in for the
end of the week with temperatures cooling slightly. Enough
westerly/southwesterly flow expected to limit potential for deep
convection over the mountains.

-CJM

&&

.AVIATION...

Local MVFR/IFR conditions in HZ/FU near wildfires, otherwise VFR
continues over the area for the next 24 hours. Winds below 15
knots. Local SW surface wind gusts 15-25 kts vicinity Delta.
&&

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

$$