Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 192119
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
219 PM PDT Sat Aug 19 2017

.SYNOPSIS...
Temperatures near to slightly above normal through the upcoming
week with daily afternoon to evening mountain thunderstorms.

&&

.DISCUSSION...
Upper troughing moving into NorCal today, resulting in slightly
cooler temperatures, though still very warm across northern
Sacramento Valley. Northerly winds across northern portions of the
state funneling smoke from wildfires across Oregon, causing very
hazy skies from about Red Bluff northward. This likely will
continue into Sunday. Instability and moisture flowing up from
the south have resulted in another afternoon of showers and
thunderstorms near the Sierra crest. A few could produce locally
heavy rainfall and small hail.

Not much change into next week as digging upper trough deepens
upper low which will remain just off the SoCal coast into Tuesday.
This will continue to draw moisture north into the area, with
daily chances for afternoon showers and thunderstorms across the
mountains, possibly even the coastal range by Monday. Thunderstorms
look to be most numerous on Tuesday with more widespread activity
across higher terrain. Still looks like mostly clear skies Monday
morning for eclipse viewing around here, though could be some
smoke lingering for locations closer to the Oregon-California
border. Onshore flow and deepening marine layer will also provide
cooling, some 2-6 degrees from today to Tuesday. Highs will top
out near normal by then.

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
Forecast models suggest afternoon convection continuing through
Wednesday as weak upper low lingers south of the forecast area.
The low is progged to move inland Wednesday into Thursday as an
upper trough moves through the Pacific Northwest. This should end
the late-day convection threat over higher terrain Thursday into
the weekend. Temperatures will remain near average at least
through Friday before warming returns to the region. Model
guidance indicates an upper ridge building across interior NorCal
late next week. As a result, temperatures will be generally 5-8
degrees above normal by the end of the forecast period.

&&

.AVIATION...
Mainly VFR conditions the next 24 hours at the TAF sites. Brief
periods of MVFR conditions possible from KRBL northward due to
wildfire smoke. Isolated afternoon thunderstorms over higher
terrain through 01z- 03z Sunday. Winds under 10 knots except in
the Delta where gusts to 30 knots will be possible. Isolated
Sierra thunderstorms possible Sunday afternoon.

&&

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

&&

$$


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