Excessive Heat and Heat in California, August 3 to 4, 2021

Name: Excessive Heat and Heat in California, August 3 to 4, 2021
Start: 2021-08-03T10:00
End: 2021-08-04T19:00
Location: California

August 3 to 4, 2021 · NWS HNX · 10 events in 10 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 10

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS HNX wrote it up.

A strong ridge of high pressure aloft centered over southern Nevada August 3 and 4 provided for a period of excessive heat over the Kern County Deserts prompting an Excessive Heat Warning for both days. In addition, much of the San Joaquin Valley was impacted by significant heat on August 4. Temperatures cooled to below dangerous levels on August 5 as a low pressure system pushed through northern California and weakened the ridge.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Hanford, CA wrote its last area forecast discussion before the first event at Aug 3, 1:40 AM PST, 8 hours 20 minutes earlier.

Area forecast discussion, Aug 3, 1:40 AM PST, 8 hours 20 minutes before

Area Forecast Discussion
National Weather Service Hanford CA
240 AM PDT Tue Aug 3 2021

.SYNOPSIS...Temperatures will continue to run above normal through
Wednesday across the area due to a strong ridge of high pressure
aloft. Cooler and breezier on Thursday as a trough of low pressure
passes through northern California. Temepratures are expected to
rebound by the end of the week. Dry weather is forecast for the
entire forecast period.

&&

.DISCUSSION...Strong upper high pressure ridge centered over
southern NV continues to be the dominant weather feature for our
area. This feature will provide for a warming trend across our
area today as it has strengthened somewhat since yday. As a
result, afternoon highs will be in the triple digits across the
nearly all of the San Joaquin Valley and West Side Hills as well
as much of the Sierra foothills. Across the Kern County Deserts,
afternoon highs will generally be between 105 and 110 Deg F today
and rise by 2-3 Deg F on Wednesday. Thus, an Excessive Heat
Warning remains in effect for the Kern County Deserts for
Wednesday.

An upper level low pressure system is still progged to push
through Norcal on Monday which will result in a noticable cooling
trend across our area as the large high weakens with daytime
temperatures expected to lower to near seasonal normals. In fact,
the latest NBM probabilistic guidance is indicating that high
temperatures on Thursday will be below 100 Deg F Fresno is 71
percent for Fresno and 72 percent for Bakersfield. The low to our
north will also strengthen onshore p-grads resulting in a brief
period of increased winds over the Kern County Mountains and
Deserts Thursday afternoon and evening.

Ensemble means are indicating the cooling trend will be short
lived as temperatures bounce back to above normal levels by next
weekend. A dry westerly flow will prevail across our area from
Thursday through at least next Monday. This will keep our area
free of precipitation with mainly clear skies prevailing.

&&

.AVIATION...VFR conditions will prevail through the next 24
hours.

&&

.AIR QUALITY ISSUES...On Tuesday August 3 2021... Unhealthy for
sensitive groups in Tulare County. 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.html for additional information
an/or to provide feedback.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM to 8 PM PDT Wednesday for
CAZ198-199.

&&

public/aviation/fire wx...DS
pio/idss...BS

weather.gov/hanford

Event by event

8 heat, 2 excessive heat. Local standard time, as filed.

Excessive Heat, Indian Wells Valley

When: August 3, 10:00 AM PST to August 4, 7:00 PM PST
Where: Indian Wells Valley forecast zone
Reported by: Mesonet

Daytime highs ranged between 108 and 114 degrees on August 3 and August 4.

Excessive Heat, Kern County Desert

When: August 3, 10:00 AM PST to August 4, 7:00 PM PST
Where: Kern County Desert forecast zone
Reported by: Mesonet

Daytime highs ranged between 108 and 114 degrees on August 3 and August 4.