Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 242254
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
354 PM PDT Sat Jun 24 2017

.SYNOPSIS...Slightly lower temperatures this weekend but still
well above normal. A few afternoon and evening thunderstorms
remain possible mainly over the Southern Sierra Nevada through
Sunday. Dry conditions and more noticeable cooling will occur
early next week.

&&

.Discussion...
Thunderstorms developed early this afternoon over the Sierra high
country and kern county mountains. The increase threat for
convective storms is due to subtropical moisture with a
disturbance off the coast moving north. Models prog the
disturbance pushing North tonight taking the threat of storms
towards the Diablo Mountains and Yosemite area this evening. The
forecasted high temperatures for today will likely not be reached
due to the increased cloud cover with the mid level moisture. The
Vandenberg sounding show dry lower levels with moisture above
10kft. Thus do not expect much precipitation to reach the
foothills and valley. Think main threat with these storms may be
dry lightning. Storms should move Nwd with a moderate mid level
from the se at 25kt and keep flood threat to a minimum.

High pressure over the region continues to dominate but is
weakening a bit. This will allow temperatures to cool slightly
this weekend, except for the desert where little change is
expected. Despite this, most of the San Joaquin Valley and lower
foothills will still see triple digit highs. Due to the prevailing
100+ degrees highs forecast, a Heat Advisory is in effect through
the weekend for the SJ Valley, foothills, and Kern County
Mountains. As mentioned earlier, the Kern County Desert will
continue to see temperatures climbing to 106-113. Thus, an
Excessive Heat Warning remains in effect there through the
weekend.

An approaching low off the coast moving towards NCal will turn
flow southwest bringing a drier airmass over the central coast.
This should limit the convective threat towards the High sierra
on Sunday afternoon. A more widespread and significant cooldown
is expect early next week as an EPAC upper trough moves in over
northern California. This will drop temperatures down about 10
degrees from Sunday to Tuesday. Highs in the SJ Valley will be
back to more seasonable levels for late June, the lower to mid
90s. Also, stronger onshore surface flow will spread more marine
air into the SJ Valley. More comfortable night time temperatures
will occur with some parts of Merced County and western Fresno
County dropping into the upper 50s overnight. Little change is
expected through the rest of the week with a general zonal flow
aloft.

People should continue to take extra precautions this weekend
with widespread triple digit heat expected. Try to avoid outdoor
activities during the heat of the day. Preferably, wear light
colored, loose fitting clothing. Take breaks, seek out shade, and
remember to stay hydrated. Children and the elderly are the most
susceptible to the heat. Also, don`t forget to provide water and
shelter for pets and livestock.

Snow melt continues from the high Sierra with rivers and streams
running very high and fast. A Flood Warning is in effect along
part of the Kings River due to increased releases from Pine Flat
Dam. Also, a Flood Advisory is in effect along the San Joaquin
River below Friant Dam due to high water releases. Remember too,
the rivers may look inviting during the heat, but the cold

&&

.AVIATION...
Isolated thunderstorms are possible over the higher elevations of
the Southern Sierra Nevada until 06Z Sunday and again from 21z
Sunday to 04z Monday. Otherwise, VFR conditions will prevail across
the central CA interior during the next 24 hours.
...END..

&&

.AIR QUALITY ISSUES...
On Sunday June 25 2017... 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 high.
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.
&&
.AVIATION...
Isolated thunderstorms are possible over the higher elevations of
the Southern Sierra Nevada from 21z Friday to 04z Saturday.
Otherwise, VFR conditions will prevail across the central CA
interior during the next 24 hours.

www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Heat Advisory until 9 PM PDT Sunday CAZ089>095.

Excessive Heat Warning until 9 PM PDT Sunday CAZ098-099.

&&

$$

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