Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 142118
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
218 PM PDT Mon Aug 14 2017


.SYNOPSIS...
Cooler early this week, then warming back to near or slightly
above average around mid-week. Slight chances for an isolated
mountain afternoon thunderstorm mid week.

&&

.DISCUSSION (Today through Thursday)...

Water vapor and model analysis indicated a small shortwave trough
disturbance continuing to slide across northern California during
the early afternoon, which brought some high level cloud cover
this afternoon. Temperatures across the valley ranged from 90 at
Redding to 75 at Sacramento in the early afternoon, with
temperatures in the low to mid 70s in the delta and mountains.

Upper level disturbance will continue to deepen across the Great
Basin as upper level high sets up in the eastern Pacific over the
next several days. Northwest flow will continue through this week,
which will result in below normal temperatures today through
Tuesday. Temperatures will gradually warm back to near normal
across the forecast area by mid week as ridge strengthens in the
eastern Pacific. There will be some mid level instability over
the mountains during the afternoon hours, so a chance for an
isolated mountain thunderstorm cannot be ruled out, but confidence
is low to location and development of any storms.

&&

.EXTENDED DISCUSSION (Friday THROUGH Monday)

Ridging begins to break down on Friday as upper level troughing
moves onshore for the weekend into early next week. As troughing
returns and a bit of moisture is drawn north, isolated
thunderstorms will be possible Friday and Saturday afternoons near
the Sierra crest south of Tahoe. Temperatures will cool slightly
from Friday to Sunday with afternoon highs back within a few
degrees of normal.

&&

.AVIATION...

VFR conditions through the TAF period. Gusts up to 20 kts for
southern Sac and northern San Joaquin valleys, as well as gusts to
around 30 kts through the Delta.

&&

.STO WATCHES/WARNINGS/ADVISORIES...

None.

&&

$$



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