Heat in California, August 27, 2019

Name: Heat in California, August 27, 2019
Start: 2019-08-27T10:00
End: 2019-08-27T20:00
Location: California

August 27, 2019 · NWS HNX · 15 events in 15 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 15

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 large area of high pressure dominated over the region between August 25 and 27. Temperatures across the San Joaquin Valley and southern Sierra foothills nudged upward back into the triple digits by August 25 and prompted the issuance of a Heat Advisory for the San Joaquin Valley and southern Sierra foothills by the 27th as well as an Excessive Heat Warning for the Kern County Deserts where highs approached 110 degrees. The high slowly broke down on August 28 and 29 giving way to a cooling trend across the area although temperatures remained above seasonal normals for late August as they were for much of the month.

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 27, 3:08 AM PST, 6 hours 52 minutes earlier.

Area forecast discussion, Aug 27, 3:08 AM PST, 6 hours 52 minutes before

Area Forecast Discussion
National Weather Service Hanford CA
408 AM PDT Tue Aug 27 2019

.SYNOPSIS...
Very hot day across central California today. Cooling trend
Wednesday through this weekend as some weakening in the ridge
occurs. Afternoon thunderstorm or two is possible today and
Wednesday across the Sierra Nevada.

&&

.DISCUSSION...
Large scale ridge axis over the region will interact with the
remnants of TS IVO and associated inverted trough off the central
California coast. Increase in humidity as well as cloud cover will
be the greatest impacts as isolated showers and a possible
thunderstorm is expected across the high Sierra today and tomorrow
during the afternoon.

Temperatures will be the hottest to day and new guidance has
bumped them up enough to warrant a heat advisory for the SJV and
an excessive heat warning for the Mojave Desert. Ridge axis
shifts to the east on Wednesday and we will some minor cooling
across the region, but still above normal values for this time of
year.

The upper level high pressure center will remain in SOCAL through
the week with continued above normal temperatures across the
region and dry conditions expected. The high pressure will shift
east as a low pressure center will move towards the PACNW by
Sunday and inland by Monday. This system will squash the ridge and
allow some onshore flow to cool us down a bit early next week.
Still looks to be a warm weekend with above normal temperatures.

&&

.AVIATION...
Isolated mountain crest thunderstorms possible from 18z to 03z
today. Otherwise, VFR conditions can be expected over the
central California interior during the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Tuesday August 27 2019... Unhealthy for sensitive groups in
Fresno and Kern 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 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...
Heat Advisory from 1 PM this afternoon to 7 PM PDT this evening
for CAZ179>191.

Excessive Heat Warning from 1 PM this afternoon to 7 PM PDT this
evening for CAZ198-199.

&&

public/fw/aviation....JDB

weather.gov/hanford