Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 182150
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
250 PM PDT Sun Jun 18 2017

.SYNOPSIS...A strong ridge of high pressure will maintain very
hot conditions across the area through at least Thursday with
near record temperatures. Isolated afternoon thunderstorms are
possible along the Sierra crest each day through Tuesday.

&&

.DISCUSSION...
The big warmup continues across central California this afternoon,
with 24 hr trends generally up around 3-6 degrees. Skies are sunny
across most of the area except in the higher terrain where
convective clouds are popping, especially near the snow line.
Before the end of daytime heating, we could see a few
thunderstorms develop in these areas this afternoon.

Models remain consistent in progging further strengthening of the
large high pressure ridge responsible for our impending heat wave.
As the high pressure center slowly settles over the southwest
states, the ridge will expand northwestward through Tuesday and
temperatures will continue to climb to near and above record
values at many locations. A weak shortwave trough is progged to
track by mainly to our north and disrupt the expanding ridge
slightly. This should have little effect on our temperatures,
other than to limit further warming, generally maintaining similar
very hot temperatures through the middle of the week. Overnight
lows are forecast to remain elevated well above normal during
this period as well, offering little relief from the heat of the
day. The excessive heat warning remains in effect through
Thursday.

Developing low pressure over the northeast Pacific is expected to
begin weakening the ridge over our region toward the end of the
week. There could be a few degrees of cooling by next weekend most
notably in the higher elevations and up around Merced County where
some cooler marine air may trickle in. Despite any slight
cooldown, temperatures will remain well above average.

Rivers continue to run cold and fast with the abundance of melting
snow, and the Merced River at Pohono is forecast to go slightly
above flood stage by very early Monday morning and again for the
next few mornings. A flood warning has been issued for this event.



&&

.AVIATION...
VFR conditions can be expected throughout the Central California
interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Monday June 19 2017... Unhealthy for sensitive groups in Fresno
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 high.

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...
Excessive Heat Warning until 11 PM PDT Thursday
CAZ089>095-098-099.

&&

$$

public...JEB
avn/fw...DCH
synopsis...JEB

weather.gov/hanford



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