NATIONAL WEATHER SERVICE FORECAST DISCUSSION
Area Forecast Discussion
Issued by The National Weather Service
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197
FXUS66 KSTO 201007
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
307 AM PDT Fri Jul 20 2018

.SYNOPSIS...
Temperatures will gradually decrease the remainder of the week
with the potential for thunderstorms in the mountains. Hot
weather returns next week.

&&

.DISCUSSION...
Clear skies across interior NorCal early this morning. Current
temperatures range from the upper 40s to mid 50s in the mountain
valleys to the mid 60s to mid 70s across the Central Valley
(except lower to mid 80s across the north end of the Sacramento
Valley).

Strong upper ridging of the past several days will weaken a bit
through the end of the week as an upper low traverses southern
BC with a weak trough trailing back into NorCal. The combination
of a little stronger onshore flow along with slight synoptic
cooling will result in a little cooler temperatures across the
region over the next few days.

Additionally, an increase in monsoon moisture will bring greater
cloud cover helping to edge temperatures down a bit as well. With
the return of monsoon moisture spreading further north,
thunderstorm activity will become more widespread across interior
NorCal through the weekend. Most of the action is expected to be
diurnal in nature and mainly over the mountains, but we can`t
completely rule out a slim chance for a few storms occurring
elsewhere tonight and early Saturday as moisture spreads north.

The ridge is forecast to reassert itself early next week resulting
in a return to hot weather and capping the extent of mountain
thunderstorm activity.

&&

.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
An expansive upper level ridge will bring hot weather across the
region next week. By even July standards, this upper ridge will
likely be rather anomalous, with NAEFS (North American Ensemble
Forecast System) guidance projecting 500mb heights to be 3-4
standard deviations higher than normal over AZ/NM. We will be on
the northern fringe of this upper ridge, but with high confidence
in the pattern we nudged temperatures up a few degrees across much
of the extended period. Current consensus of solutions has
widespread triple digit heat across much of the Central Valley
through the extended period, with temperatures potentially
approaching 110 degrees again across the northern Valley. Dang

&&

.AVIATION...
VFR conditions the next 24 hours across TAF sites. South to west
winds 5 to 15 knots, except gusts to 30 kt near the Delta. Dang

&&

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

&&

$$
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