High pressure over the Desert Southwest led to above normal temperatures and excessive heat warning conditions across the region. The deadly heat led to 6 fatalities (4 direct and 2 indirect) according to the Maricopa County Department of Public Health.
Every event with a place to put it; 24 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS PSR wrote it up.
High pressure over the Desert Southwest led to above normal temperatures and excessive heat warning conditions across the region. The deadly heat led to 6 fatalities (4 direct and 2 indirect) according to the Maricopa County Department of Public Health.
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 Phoenix, AZ wrote its last area forecast discussion before the first event at Aug 25, 3:31 PM MST, 1 hour 29 minutes earlier.
Area Forecast Discussion
National Weather Service Phoenix AZ
331 PM MST Sun Aug 25 2019
.SYNOPSIS...
A warming trend can be expected during the first half of the
workweek. This will lead to high temperatures several degrees
above normal on Tuesday and Wednesday. Portions of south-central
Arizona are expected to reach excessive heat thresholds. Humidity
will trend down as well...most noticeably on Tuesday. Humidities
trend up Wednesday and especially Thursday with an increase in
storm chances...mainly for the higher terrain of south-central
Arizona. Temperatures trend down on Thursday as well. Humidities
and storm chances fluctuate over the weekend with the best chances
for storms on Sunday.
&&
.DISCUSSION...
Monday through Wednesday...
Lower troposphere remains quite humid but satellite imagery for
early this afternoon shows very little activity thanks to having too
much CIN. There may still be something that PoPs over Joshua Tree
N.P. and maybe eastern Gila County. There will still be fairly
humid conditions tomorrow as another seep of Gulf of California
moisture comes in tonight. But, high pressure (currently centered
near San Francisco) continues to expand southeastward (increasing
CIN). By Tuesday, the high becomes centered east-southeast of
Arizona. In the process, there will be a warming and drying trend.
In fact, temps over portions of south-central AZ reach high Heat
Risk thresholds and thus an Excessive Heat Watch is in effect. The
Watch goes through Wednesday as the high center shifts westward a
bit. Models dip temperatures slightly on Wednesday (with an
increase in humidity) but not enough to eliminate the high Heat
Risk. PoPs go up over our easternmost areas due to the moisture
increase.
Thursday through Sunday...
There is good model agreement that temperatures trend down for
Thursday. This appears to be due to a more significant influx of
moisture that comes in Wednesday night and Thursday morning
(mainly near and east of the Lower Colorado River Valley) in the
wake of an inverted trough passing to the south. By Thursday
afternoon, the 500mb high becomes centered near San Diego leading
to a northerly component to the steering flow. While this can be
favorable for getting storms to advect off the Rim and Yavapai
County, there will be a trade off with drier air coming in.
Temperatures are anticipated to nudge upward again on Friday with
additional drying (though the southeast quarter of AZ looks to
maintain some decent moisture). Anticipate our western areas will
approach excessive heat thresholds. Over the weekend, the high
center tracks northeastward to near the AZ/UT border. This leads
to more of a favorable steering flow pattern an in turn better
moisture availability (possibly aided by another inverted trough)
with Sunday having higher PoPs than Saturday. Temps nudge back
down as well.
&&
.AVIATION...Updated at 1730 UTC.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will be the primary forecast issue through Monday afternoon
with overall weather conditions not too dissimilar from Saturday
afternoon/evening. FEW-SCT fair weather Cu forming off surrounding
mountains will have bases increasing from FL050 to FL080 through the
afternoon before evaporating prior to sunset. Westerly sfc winds
will prevail through most of the period with only some variability
in outlying terminal sites Monday morning. The more unusual aspect
is another bout of gusty winds (around 20 kt) likely not settling
into the Phoenix area until later in the evening and overnight due
to another surge of moisture from the SW. Confidence in this outcome
is moderate.
Southeast California/Southwest Arizona including KIPL and KBLH:
Wind shifts and occasional gustiness will the main forecast
challenge through Monday afternoon. Shallow fair weather Cu were
already dissipating to some extent late this morning; and other than
high cirrus, more extensive building clouds should be limited over
mountains this afternoon. Some form of a southerly wind component
should prevail though large amounts of variability are possible -
particularly at KIPL. Confidence in timing any wind direction shifts
and potential gusts is only low to moderate.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday:
Humidities trend up on Wednesday and Thursday. Storm chances
increase as well - for south-central Arizona. Humidities and storm
chances fluctuate at the end of the week and over the weekend with
the best chances for storms on Sunday. Minimum humidities are
expected to be lowest on Friday but remain above 10%. Similarly,
overnight recovery is anticipated to be lowest on Friday night but
remain at least fair. Apart from thunderstorms, no strong wind
events are anticipated but breezy to locally windy conditions from
a Gulf surge couldn't be ruled out.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Watch from Tuesday morning through Wednesday
evening for AZZ534-537-538-540>544-546-548>551-553>556-558-
560-562.
CA...None.
&&
DISCUSSION...AJ
AVIATION...MO
FIRE WEATHER...AJThe national radar mosaic for the moment the first event began.
21 excessive heat, 3 heat. Local standard time, as filed.
One indirect fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender and circumstances unavailable.
One indirect fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender and circumstances unavailable.
Three direct fatalities were reported by the Maricopa County Department of Public Health, with their details, such as age, gender and circumstances unavailable.
One direct fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender and circumstances unavailable.
One indirect fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender and circumstances unavailable.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Central Phoenix | 2019-08-25 | Unknown | Indirect | ||
| Heat, East Valley | 2019-08-25 | Unknown | Indirect | ||
| Excessive Heat, Central Phoenix | 2019-08-27 | Unknown | Direct | ||
| Excessive Heat, Central Phoenix | 2019-08-28 | Unknown | Direct | ||
| Excessive Heat, Central Phoenix | 2019-08-28 | Unknown | Direct | ||
| Excessive Heat, East Valley | 2019-08-27 | Unknown | Direct | ||
| Heat, Central Phoenix | 2019-08-29 | Unknown | Indirect |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2019Every state in 2019This day in weather historyWarnings in Arizona, August 2019
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 931104, 931105, 931112, 931113, 931117, 931118, 931119, 931120, 931121, 931122, 931123, 931125, 931127, 931128, 931129, 931130, 931131, 931132, 931133, 931134, 931135, 931136, 931137, 931116.