Heat Advisory 1, NWS Hanford, CA

Area Forecast Discussion...UPDATED
National Weather Service Hanford CA
334 PM PDT Sun May 30 2021

...Update to Air Quality Issues Section...

.SYNOPSIS...A few thunderstorms remain possible in the Sierra
until sunset today. Dangerously hot temperatures will impact a
majority of the central California interior Memorial Day through
Wednesday. Temperatures are expected to be around 12-17 degrees
above normal with some new record highs possible in parts of the
San Joaquin Valley. Some cooling will occur later in the week but
afternoon temperatures will remain well above normal.

&&

.DISCUSSION...
Visible satellite imagery shows lots of cumulus clouds developing
over the southern Sierra Nevada this afternoon as a weak upper low
spins over southern California and northern Baja CA. Radar detects
some light showers mainly over Sequoia National Forest in Tulare
County but extending as far south as Lake Isabella in Kern County.
Hi-Res models suggest this activity will continue for a few more
hours before diminishing by sunset. There is still a small chance
of an isolated thunderstorm or two as well.

An East Pacific ridge of high pressure is beginning to build inland
over northern California. This has resulted in some warming today
as 24 hour trends are running up 2-5 degrees. Highs are forecast to
top out in the mid 90s across the SJ Valley this afternoon, around
5-10 degrees above climatological normals for the end of May. The
ridge continues to build inland Monday for more significant warming.
Widespread triple digit heat will occur across the lower elevations,
with afternoon highs forecast to range from 101-107 degrees, around
12-17 degrees above normal. Some record highs may be tied or broken
in parts of the SJ Valley. Tuesday looks to be a near carbon copy.
An Excessive Heat Warning is in effect for the San Joaquin Valley,
the West Side Hills, and the Sierra Foothills for Monday and Tuesday.
An Excessive Heat Watch is in effect for the same areas on Wednesday
as temperatures only lower slightly.

Ensembles shift the ridge to the east later in the week as an upper
trough moves over the Pacific Northwest. Temperatures will lower a
few degrees both Thursday and Friday but afternoon highs are still
expected to around 7-10 degrees above normal by Friday. Next weekend
looks to remain dry with temperatures at least a few degrees above
normal.

&&

.AVIATION...VFR conditions will prevail across the Central CA
interior through at least the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Monday May 31 2021... Unhealthy for sensitive groups in Fresno...
Kern... Kings 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.html for additional information
an/or to provide feedback.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from noon Monday to 8 PM PDT Tuesday for
CAZ179>191.

Excessive Heat Watch from Wednesday afternoon through Wednesday
evening for CAZ179>191.

&&

Public/Aviation/Fire Wx........DCH
PIO/DSS/Social Media...........Durfee

weather.gov/hanford