Heat in California, June 1 to 4, 2021

Area Forecast Discussion...update
National Weather Service Hanford CA
445 AM PDT Tue Jun 1 2021

...UPDATED TO ADD EXCESSIVE HEAT WATCH FOR THE KERN COUNTY DESERT
FOR WEDNESDAY AND THURSDAY...

.SYNOPSIS...Widespread triple digit heat can be expected in the
San Joaquin Valley, lower foothills and the Kern County desert
during the next few afternoons. High temperatures will trend a bit
lower later this week through the weekend but still remain well
above normal. Otherwise, dry weather will prevail over the district
for the next several days.

&&

.DISCUSSION...If you're not a fan of triple digit heat, this will
not be a good week for you if you live in the San Joaquin Valley,
lower foothills and the Kern County desert. If it's any consolation,
high temperatures will trend downward a bit after Wednesday. If the
ensembles are right, there will be no appreciable cooling over the
central California interior until early next week. As it looks now,
we're not expecting a return to near normal high temperatures until
next Tuesday. The next couple of afternoons will be downright hot in
the San Joaquin Valley, lower foothills and the Kern County desert.
Many locations are destined to reach their hottest temperatures yet
this year. A couple of sites in the San Joaquin Valley may tie or
break their record high temperature today and Wednesday. Statistically,
there is a 46 percent probability that the record high of 103 degrees
in Merced today will be reached. The probability that Fresno reaches
its record high of 105 degrees this afternoon is 40 percent.

As we step back and look at the overall pattern, we see a strong upper
level ridge of high pressure that extends from the Hawaiian islands
northeastward to the Pacific Northwest coast this morning. During the
past couple of afternoons, isolated mountain convection has developed
south of this ridge mainly over the Sequoia National Forest. The
atmosphere should become more stable over this region during the next
48 hours as the center of the upper level ridge shifts southward over
the Golden State. The models forecast this ridge to remain parked over
central California through Thursday. That's a day longer than the models
predicted a few days ago. That being said, it would not be a surprise if
this ridge continued to hang on and dominate our weather pattern through
Friday as it now looks like the upstream trough will be slower to approach
the central California coast and will likely remain offshore later this
week. In fact, the ECM and the NAM 12 solutions keep this low so far
offshore later this week that it's doubtful this system will have much
if any impact on our weather except to shave a few degrees off maximum
temperatures Friday through the weekend. Although a few thunderstorms
could pop up over the highest elevations of the Sierra the next few
afternoons, dry weather will be the rule and the fire danger will remain
high.

So the question remains whether (or not) the weak offshore low later this
week will have any influence on our weather pattern beyond Friday. The
answer to that question at this time is "probably not". The models agree
that this moisture deficient cutoff low will remain offshore the California
coast and drift inland across northern Baja Sunday night or Monday before
tracking toward the Four Corners region Monday night. The good news is that
an onshore flow is forecast to become established across central California
one week from today.  If so, temperatures will trend significantly lower by
day 7. By next Tuesday, ocean cooled air will hopefully infiltrate the San
Joaquin Valley and finally cool temperatures to seasonable levels. In the
meantime, folks should keep safety tips in mind during this heat wave. If
you're going to be outdoors, lather on the sunscreen, wear a protective hat
and light colored, loose fitting clothing. Most importantly, stay hydrated,
limit your physical activity and stay out of the sun, especially during the
hottest part of the day.

&&

.AVIATION...
VFR conditions can be expected throughout the central California interior
for at least the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Tuesday June 1 2021... Unhealthy for sensitive groups in Fresno...Kern...
Kings...Madera and Tulare Counties. 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 until 8 PM PDT this evening for CAZ179>191.

Heat Advisory from noon to 8 PM PDT Wednesday for CAZ180-181-190.

Excessive Heat Warning from noon to 8 PM PDT Wednesday for
CAZ179-182>189-191.

Excessive Heat Watch from noon to 8 PM PDT Wednesday and Thursday
for CAZ198-199.
&&

synopsis...Durfee
public/aviation/fw...Durfee
PIO/IDSS...Durfee

weather.gov/hanford