Wildfire in California, August 16 to 31, 2016

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
326 PM PDT TUE AUG 16 2016

.UPDATE...Updated air quality issues.

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.SYNOPSIS...
High pressure over the west will keep warm and dry conditions in
place through most of the week. Expect slightly lower, but still
warmer than average, temperatures. Occasional upper-level
disturbances and mid-level moisture will bring sufficient
instability for isolated thunderstorms along the Sierra Nevada
crest.

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.DISCUSSION...The high pressure ridge that produced extreme heat
over the lower elevations of the central California interior last
weekend has been forced well offshore by a weak upper level trough
now situated over the northern part of the state. It's the main
reason temperatures are trending slightly lower across much of the
cwa this afternoon compared to yesterday afternoon. Otherwise, a
dry air mass remains in place over the central California interior
today as evidenced by current water vapor imagery. During the next
day or so, the upper level trough will settle southward and the
atmosphere will become a little less stable over the highest
elevations of the cwa. Convection, which has been slow to develop
this afternoon, has been so far confined to Mono County and most
of western Nevada. However, isolated thunderstorms might start
popping up near the Sierra Crest tomorrow afternoon and on
following afternoons through Friday as the upper level low drifts
southward. The most unstable atmospheric environments are usually
on the eastern side of these upper level Lows where there is just
enough lift and mid level moisture present. Even so, moisture is
still rather sparse with this feature, so thunderstorms over the
high sierra will be isolated at best the next few afternoons.
Otherwise, the proximity of this upper level low will keep humidity
and temperature trends rather static for the remainder of the work
week.

The remnants of this weak 500 mb low will end up off the southern
California coast this weekend and allow room for a high pressure
ridge aloft to nose southward into central California in the 4 to
7 day period. The models forecast a slightly drier and more stable
air mass to settle back in over the CWA during that time. High
temperatures should trend upward as a result. However, mos
guidance is pulling its usual tricks and weighing in climatology,
so it would not be a surprise if triple digit heat became more
widespread in the San Joaquin Valley and lower foothills Saturday
through next Tuesday. Whatever the case, max temperatures will
probably average warmer than normal (and climatological normals
are dropping) in the 4 to 7 day period. Although we maintain slight
chance POPS near the Sierra crest each afternoon in the extended
periods, there may not be any more than cumulus buildups each day
over the high Sierra from Saturday on.

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.AVIATION...
VFR conditions expected throughout the Central California Interior
for the next 24 hours.

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.AIR QUALITY ISSUES...
On Tuesday August 16 2016... Unhealthy for sensitive groups in
Fresno... Kern... Kings... Madera... Merced and Tulare Counties and
Sequoia National Park and Forest.
Further information is available at Valleyair.org

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.CERTAINTY...

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

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

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.HNX Watches/Warnings/Advisories...
NONE.
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public...Durfee
avn/fw...Durfee
synopsis...BSO

weather.gov/hanford