Heat in California, July 7 to 9, 2017

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
325 AM PDT Fri Jul 7 2017

.SYNOPSIS...
A strong upper level ridge of high pressure will remain anchored
over the Four Corners region for the next few days. Temperatures
will remain above normal through at least Monday with a slight
chance of afternoon thunderstorms each day over the higher
elevations of the Sierra. Isolated thunderstorms are also possible
in the Kern county mountains and desert Sunday.

&&

.DISCUSSION...
Summer is in full swing across the West as the region heats-up
under a strong ridge pattern. The four corners high that has
dominated the weather over the West Coast will continue to
influence conditions in the short term across the Central
California Interior. Currently, an Excessive Heat Warning is in
effect for the Kern County Deserts as well as a Heat Advisory for
the San Joaquin Valley. The heat related products will remain in
effect through Saturday evening before the region begins to cool
down. Furthermore, surface analysis from across the Southwest show
widespread dew points in the 40s and 50s. These values continue
into the Central California Interior where values have even reach
into the lower 60s. Therefore, confidence is high that hot and
humid conditions will warrant the current warnings and advisory
posted. In addition to the heat, the moist air will facilitate the
development of convection across the area. With instability
confined to the mountains, will keep a mention of showers and
thunderstorms to the Sierra Nevada (mainly near the Crest).

The warming trend is expected through possibly the Sunday time
frame as models show the ridge pattern holding strong for a few
more days. By Sunday, models show a piece of energy riding over
the ridge and having the potential to enhance mountain
thunderstorm development. Therefore, will place Sunday as the time
frame for the scattered convection. This disturbance on Sunday
may also provide cloud cover and more of an onshore flow to limit
the heat. Therefore, will not include Sunday in the heat related
statements as temperatures are expected to remain below criteria.
Beyond the Sunday time frame, mountain convection will remain
isolated for much of the forecast cycle. By Monday, a deeper
through moving through the Pacific Northwest and Northern
California will help break-down the ridge pattern and increase the
westerly flow aloft. This change in the wind direction will
continue lowering the threat of convection and help lower
temperatures across the region.

Model confidence still lacking toward the latter parts of next
week, but do hint toward the continuation of the onshore flow
pattern. Models show another piece of energy pushing through mid-
week to help maintain convection over the mountains. At the same
time, an upper low with high uncertainty moves closer toward the
Pacific Northwest. Models are having a difficult time resolving
this feature, but do place it somewhere near the Pacific
Northwest. This placement will result in pushing the upper high
eastward and reducing the threat of subtropical moisture being
advected Northwestward and into Central California.

&&

.AVIATION...
Areas of smoke from the Schaeffer wildfire will persist in the
Tulare county mountains for at least the next 24 hours. Isolated
thunderstorms can be expected near the Sierra Crest between 19z
Friday and 05z Saturday. Otherwise, VFR conditions will prevail
across the Central CA Interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Friday July 7 2017...Unhealthy for sensitive groups in
Fresno, Kern, Kings, Madera 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.

&&

.HNX Watches/Warnings/Advisories...
Heat Advisory from 1 PM this afternoon to 11 PM PDT Saturday
CAZ089>092.

Excessive Heat Warning from 1 PM this afternoon to 11 PM PDT
Saturday CAZ098-099.

&&

public...Molina
avn/fw...Riley
synopsis...Molina

weather.gov/hanford