Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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492
FXUS66 KHNX 182329
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
429 PM PDT Wed Jul 18 2018

.UPDATE...Updated air quality issues.

&&

.SYNOPSIS...Subtropical moisture will continue to flow from the
southeast during the next couple of days and will bring a chance
of thunderstorms to mainly the mountains and desert. Otherwise,
temperatures will continue warm with higher humidity over the
central California interior.

&&

.DISCUSSION...Latest satellite images have been showing some
subtropical moisture that has been moving from the southeast due
to the passing disturbance (also known as an easterly wave) over
southern California. Also, some mid-level and high clouds are over
the southern half of the forecast area, including Kern, Tulare,
and Kings Counties. Clouds will continue to move northwestward
over much of the region during the next few hours. However, some
clearing has occurred over eastern Kern County, while lower level
moisture remains. So, instability has been sufficient for
isolated showers and thunderstorms that have developed over the
Kern County desert and areas mainly to the south early this
afternoon so far. Expect more showers and thunderstorms to form
later this afternoon into this evening in these areas and over the
Sierra Nevada. Otherwise, smoke will continue to produce reduced
air quality and remain a health concern in some areas due to the
Ferguson Fire to the west of Yosemite (see SFOAQAHNX, or the Air
Quality Alert issued by the SJV Air Pollution Control District for
more details).

On Thursday, there is a renewed threat of afternoon and evening
thunderstorms over the higher terrain and desert as moisture will
remain over the region. A slight chance for showers and thunderstorms
is possible in the higher terrain along the west side of the San
Joaquin Valley, as shorter-term models hint on some instability
due to the presence of subtropical moisture circulating around the
high pressure system centered over the Desert Southwest and a low
pressure system off the coast of Baja California. However,
confidence in this scenario is pretty low, while overall medium in
terms of the forecast. Otherwise, temperatures will remain
several degrees above average, though quite typical through at
least the remainder of the week. Some low level moisture will
increase over much of region, including into the Central Valley,
and it might feel a bit muggy at times on Thursday and Friday,
while some mid-level clouds will pass over Central California at
times. Models remain in general agreement that shower and
thunderstorm coverage will decrease a little on Friday and remain
over the higher elevations of the Sierra Nevada.

Showers and thunderstorms are expected to continue mainly near and
along the Sierra Nevada crest over the weekend, while temperatures
moderate slightly. However, high pressure will rebuild early next
week over much of California and the southwestern U.S., so that
temperatures will warm back up to at least several degrees above
average. Shower and thunderstorm activity remains a possibility in
the afternoons and evenings along the Sierra Nevada crest next
week.

&&

.AVIATION...
Areas of MVFR visibility in smoke will continue in the vicinity of
the Ferguson Fire in Mariposa County for at least the next 24 hours.
Isolated thunderstorms are expected over the Sierra Nevada, as well
as the Kern County Mountains and desert through 04Z Thursday and
again after 19Z Thursday. Otherwise, VFR conditions will prevail
over the central California interior during the next 24 hours.

&&

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

On Thursday July 19 2018... Unhealthy for sensitive groups in
Fresno... Kern and Tulare Counties and Sequoia National Park and
Forest. Further information is available at Valleyair.org

&&

.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...BSO
avn/fw...BSO
synopsis...BSO

weather.gov/hanford



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