The Desert Southwest remained under the influence of strong high pressure from the end of August into the beginning of September. Five direct fatalities were reported by the Maricopa County Department of Public Health.
Every event with a place to put it; 4 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.
The Desert Southwest remained under the influence of strong high pressure from the end of August into the beginning of September. Five direct fatalities were reported by 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 31, 9:46 PM MST, 2 hours 14 minutes earlier.
Area Forecast Discussion
National Weather Service Phoenix AZ
946 PM MST Sat Aug 31 2019
.UPDATE...
Updated Aviation.
.SYNOPSIS...
Well above normal temperatures will continue today with high
temperatures reaching excessive heat levels for the bulk of the
lower deserts. Tonight into Sunday, increasing moisture will lead
to better storm chances beginning Sunday afternoon, likely
affecting the south-central lower deserts to some degree Sunday
evening. Chances for mainly afternoon and evening monsoon storms
will continue through the first half of next week while
temperatures remain slightly above normal. The latter half of next
week will likely return to drier conditions and storm chances
confined to the eastern Arizona high terrain.
&&
.DISCUSSION...
Temperatures once again are heating up above 100 degrees early
this afternoon, and are on track to approach 110 degrees by late
afternoon. Excessive heat and associated impacts are still a safe
bet through this evening. Meanwhile, thunderstorm development is
underway along the Mogollon Rim and across the White Mountains.
The air mass is not exceptionally moist for late August with
precipitable water values between 1.2-1.4 inches. However, a
similar convective evolution is expected today as compared to
yesterday, with most activity expected to remain east of Phoenix,
although a few storms may approach northeast Pinal County near
sunset. More likely will be the potential for an outflow along the
northern/eastern fringes of the Phoenix area, temporarily bringing
gusty winds and perhaps some localized blowing dust. Later
tonight, an impulse potentially enhanced by convection over New
Mexico is expected to move southwestward towards south-central
Arizona. This may be sufficient to generate a few showers and
perhaps a thunderstorm between Phoenix and Tucson. However,
coverage is expected to be fairly sparse if any convection does
develop.
Into Sunday, a more substantial moistening is forecast to occur,
aided by convection near the Mexican border, while the upper high
migrates northeastward towards the Four Corners. A more favorable
setup for thunderstorms across the deserts is expected, with
strong diurnal heating potentially supporting MLCAPE values over
1000 J/kg. With the upper-level high to the northeast, easterly
flow of 10-20 kt will also support storm motions off the higher
terrain of eastern Arizona, and loosely organized multicell
clusters. Given these factors, will continue to advertise the
potential for a relatively more active day thunderstorm-wise for
south-central into southwest Arizona. Strong wind gusts, blowing
dust, and locally heavy rainfall will be possible with any
thunderstorm. Relatively rich moisture will persist into Monday,
and will continue to support isolated thunderstorm development all
the way into southeast California. However, the spatial extent of
any preceding thunderstorm activity and associated cloud cover
could substantially limit heating/destabilization on Monday,
especially across south-central Arizona, fostering more
uncertainty as to what the true convective potential will be.
Thunderstorm chances will likely persist into Tuesday as well,
with similar concerns from mesoscale influences as Monday.
Later in the week, a very gradual drying trend is expected as the
upper high remains relatively fixed in place near the Four
Corners, while a more active belt of westerlies develops across
the Pacific Northwest. Temperatures will also remain fairly
consistent during this period, a few degrees above normal for this
time of year. Low-end thunderstorm chances should continue each
day from Wednesday into next weekend.
&&
.AVIATION...Updated at 0446 UTC.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Latest high-res model output is now showing convective activity
remaining well away (mostly to the south) of the greater Phoenix
area through the rest of the night, with light/variable winds
prevailing across the region. A weak disturbance moving southwestward
into the region will likely finally switch winds to southeasterly
towards morning on Sunday. This disturbance could also produce a few
light showers as well, but confidence is now too low to put VCSH in
any of the TAFS.
A more active day definitely appears to be in the offing for Sunday
afternoon/evening as easterly flow aloft becomes stronger and
moisture levels increase as well, leading to a noticeable increase
in convective activity. Given latest high-res model consensus,
confidence is now high enough to include a strong outflow wind shift
to southeasterly and VCTS in all of the Phoenix area TAFs, as well
as BLDU in the KIWA TAF sometime during the 00Z-03Z time frame as
storms move into the lower deserts from the east, but confidence is
still too low to include blowing dust on the KPHX/KSDL/KDVT TAFs at
this time. Once the convective activity moves off to the west, winds
later on Sunday evening/Sunday night should become more typical
light easterly.
Southeast California/Southwest Arizona including KIPL and KBLH:
Anticipate typical diurnal patterns with south and southeast
directions prevailing through the TAF period at KIPL and through at
least early Sunday evening at KBLH. There is a chance that
convective activity developing well off to the east could impact
KBLH, however confidence is still too low to include any impacts in
the KBLH TAF at this time.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Tuesday through Saturday:
Thunderstorm chances will continue across most of southwest and
south-central Arizona, and southeast California, on Tuesday.
Locally heavy rain and gusty outflow winds will be possible.
Despite the increase in moisture and slight decrease in
temperatures, daytime minimum humidity values will still fall into
the 15-20% range with overnight recoveries into the 30-60% range.
Outside of any outflows, the winds will favor diurnal trends with
typical afternoon breezes. A gradual drying trend will occur
Wednesday into Friday, keeping the highest thunderstorm chances
across the higher terrain of south-central Arizona. Temperatures
will remain a few degrees above normal each day.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST this evening for
AZZ530>534-536>538-540>546-548>551-553>556-559-560-562.
CA...Excessive Heat Warning until 8 PM PDT this evening for CAZ563-
566-567-569-570.
&&
DISCUSSION...Rogers
AVIATION...Percha/AJ
FIRE WEATHER...RogersThe national radar mosaic for the moment the first event began.
4 heat. Local standard time, as filed.
One direct fatality was 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.
Two 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.
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 | 2019-09-01 | Unknown | Direct | ||
| Heat, East Valley | 2019-09-01 | Unknown | Direct | ||
| Heat, Central Phoenix | 2019-09-02 | Unknown | Direct | ||
| Heat, Central Phoenix | 2019-09-02 | Unknown | Direct | ||
| Heat, East Valley | 2019-09-02 | Unknown | Direct |
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, September 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: 931187, 931188, 931189, 931191.