Excessive Heat and Heat in California, August 14 to 16, 2021

Name: Excessive Heat and Heat in California, August 14 to 16, 2021
Start: 2021-08-14T10:00
End: 2021-08-16T19:00
Location: California

August 14 to 16, 2021 · NWS HNX · 13 events in 13 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 13

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 area of high pressure which had been centered over the Great Basin built westward into central California on August 14 and brought dangerous heat to portions of the central California interior between August 14 and August 16. Several stations in the Kern County Deserts had afternoon highs at 110 Degrees F or higher each day between August 14 and August 16. Hot daytime temperatures were also common throughout the San Joaquin Valley and West Side Hills where afternoon highs around 105 Degrees F were common. The high began to weaken on August 17 and daytime temperatures trended lower. By August 18, temperatures across the area were close to their seasonal normals.

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 14, 9:55 AM PST, 5 minutes earlier.

Area forecast discussion, Aug 14, 9:55 AM PST, 5 minutes before

Area Forecast Discussion
National Weather Service Hanford CA
1055 AM PDT Sat Aug 14 2021

.SYNOPSIS...
Isolated thunderstorms are possible in the Sierra Nevada each
afternoon today through Monday. Excessive heat is expected in the
San Joaquin Valley, Kern County desert, and Coastal Range this
weekend into early next week. A downward temperature trend will
begin Tuesday. High temperatures Wednesday afternoon and Thursday
afternoon will be near normal for this time of year.

&&

.DISCUSSION...
An upper-level area of high pressure will be centered in the
vicinity of Central California this weekend. This anticyclone
aloft will weaken Monday as an Eastern Pacific trough of low
pressure approaches the northern coast of California. Maximum
temperatures of 105 degrees or higher are likely in the San
Joaquin Valley, Kern County desert, and Coastal Range Sunday
afternoon and Monday afternoon. Probabilities of maximum
temperatures of 105 degrees or higher Monday afternoon are 68% in
Fresno and Hanford and 59% in Bakersfield. Excessive Heat Warnings
are in effect until 8 PM PDT Monday evening. In addition, isolated
thunderstorms may impact the Sierra Nevada each afternoon today
through Monday. Dangerous cloud to ground lighting strikes,
coupled with not much in the way of wetting rainfall, may be
responsible for new wildfire starts in the Sierra Nevada this
weekend into early next week.

A trough of low pressure will deepen along the coast of California
Monday night. An upper-level area of low pressure will slowly move
southward through the Pacific Northwest Tuesday through Wednesday.
This cyclone aloft may make it to Northern Nevada Wednesday night,
before progressing eastward Thursday. A ridge of high pressure
will build northwestward over California Thursday night into next
weekend. Strong, gusty westerly winds are possible in the Kern
County mountains and desert Tuesday afternoon into early Tuesday
night and Wednesday afternoon into early Wednesday night. A
downward temperature trend will start Tuesday. Maximum
temperatures Wednesday afternoon and Thursday afternoon will be
near their typical values for the latter half of August. High
temperatures Friday afternoon and Saturday afternoon will be two
to four degrees above normal for this time of year.

&&

.AVIATION...
In the Sierra Nevada, areas of MVFR and local mountain obscuring
IFR in showers and isolated thunderstorms until 03Z Sunday.
Elsewhere, VFR conditions will prevail across the remainder of
Central California through at least the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Saturday, August 14th, 2021, unhealthy for sensitive groups in
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
and/or to provide feedback.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from noon Sunday to 8 PM PDT Monday for
CAZ179>189.

Heat Advisory until noon PDT Sunday for CAZ179>189.

Excessive Heat Warning until 8 PM PDT Monday for CAZ198-199.

&&

Public/Aviation/Fire Weather...BS
PIO/DSS........................MV

weather.gov/hanford