Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 210022 AAA
AFDHNX

Area Forecast Discussion...UPDATED
National Weather Service San Joaquin Valley - Hanford CA
522 PM PDT Sun Aug 20 2017

...UPDATED AIR QUALITY SECTION...

.SYNOPSIS...An area of low pressure will remain anchored off the
southern California coast through Wednesday and bring a chance of
mainly afternoon showers and thunderstorms to the Sierra each day
with a slight chance in the Kern mountains and desert Monday. A
dry westerly flow aloft will return by Thursday.

&&

.DISCUSSION...Showers and thunderstorms once again developing
over the Sierra Nevada this afternoon as a low pressure system
remains along the southern California coast. The flow aloft is
from the east-southeast. This will bring a slight chance of a
shower or a thunderstorm drifting into the foothills early this
evening before they dissipate. Also cannot rule out storms
developing over the Kern mountains this afternoon and early
evening as well. Debris clouds from the storms will once again
move out over the San Joaquin Valley tonight.

Temperatures this afternoon are running a few degrees cooler than
yesterday thanks to a 2500 foot deep marine layer that allowed
a little cooler air to spill in last night. Temperatures are
expected to be near normal through at least mid week.

Models are in agreement that the trough will remain off the
coast through Tuesday, maintaining an east to southeast mid level
flow. However, the monsoonal moisture that was expected to come up
from the south now is forecast to stay a bit farther east. This
means that it will not make it into the Kern county mountains and
desert tonight, so have removed pops. The moisture will advect
north on Monday, but will only add a little additional moisture to
the Sierra Nevada. Expect the continuation of afternoon showers
and thunderstorms over the Sierra Monday with only a slight
chance in Kern county mountains and desert.

Models indicate a continuation of the southeast flow Monday night
and Tuesday as the low closes off point conception. However, they
also bring drier air into the southern part of the district. This
will keep the threat of thunderstorms to only the Sierra Nevada
through Wednesday.

The models forecast the trough to weaken as it moves onshore over
southern California Wednesday and another trough of low pressure
moves across the Pacific Northwest. A westerly flow aloft should
bring drier and stable conditions Thursday. A slight warming and
drying trend is expected as we go into next weekend as an upper
level ridge builds northwestward from Texas.

&&

.AVIATION...Isolated to scattered thunderstorms in the mountains
until 03z this evening with a recurrence in the mountains and
possibly the Kern county desert after 20z Monday. Otherwise VFR
conditions can be expected over much of the central CA interior
during the next 24 hours.

&&

.AIR QUALITY ISSUES...
Please see SFOAQAHNX for an Air Quality Alert.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...NONE.

&&

$$

public...Bean
avn/fw...Durfee
synopsis...Bean

weather.gov/hanford



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