Heat in Arizona, August 1 to 3, 2023

Name: Heat in Arizona, August 1 to 3, 2023
Start: 2023-08-01T10:00
End: 2023-08-03T20:00
Location: Arizona

August 1 to 3, 2023 · NWS TWC · 3 events in 3 counties and zones

Hot temperatures 2 to 4 degrees above normal August 1-3 in parts of southeast Arizona caused the Moderate Heat Risk category to be reached. A total of 11 heat-related fatalities were reported by the Pima County Medical Examiner.

Where it happened

Every event with a place to put it; 3 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 11
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 3

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 TWC wrote it up.

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 Tucson, AZ wrote its last area forecast discussion before the first event at Aug 1, 9:09 AM MST, 51 minutes earlier.

Area forecast discussion, Aug 1, 9:09 AM MST, 51 minutes before

Area Forecast Discussion
National Weather Service Tucson AZ
909 AM MST Tue Aug 1 2023

.SYNOPSIS...Storm chances decrease today with just a few isolated
storms this afternoon and evening. Thereafter, mostly dry conditions
from Tucson westward Wednesday and Thursday, with isolated to
scattered showers and thunderstorms for Graham, Greenlee, and
Cochise Counties. Friday through this weekend, generally dry
conditions will prevail as temperatures warm to record or near
record levels.

&&

.DISCUSSION...Latest IR/WV satellite imagery shows sunny skies this
morning across southeast Arizona. The area resides in a subsident
region on the backside of the disturbance/inverted trough that moved
through yesterday. Flow aloft is generally south to southwesterly
and the 12Z KTWC sounding came in with 1.41" of PWAT. However, the
atmosphere is continuing to dry out this morning per GOES Total PWAT
with Tucson around 1" to 1.1". Latest CAMS/HREF shows a fairly quiet
day with just isolated showers and perhaps an embedded thunderstorm
or two. With that said, coverage will be fairly limited and with the
activity that does occur, it doesn't look too impactful. This is
also supported by model soundings which show the drier and warmer
air moving in aloft throughout the day. Forecast is in good shape.
No updates this morning. See previous discussion below for
additional information.

&&

.AVIATION...valid through 02/12Z.
FEW-SCT clouds 10k-14k AGL this afternoon and evening. Subsidence
behind yesterday's inverted trough as well as slightly drier air
will inhibit convection today. CAMs not showing many storms today
with just a few isolated -TSRA possible in the afternoon and
likely not impacting any terminals. Sfc winds variable less than 6
kts this morning becoming southwesterly to northwesterly 8-10 kts
with gusts 15-20 kts this afternoon and early evening. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Storms will likely struggle today with limited
strength and coverage. Wednesday and Thursday expect isolated storms
mainly south and east of Tucson then mostly dry Friday into the
weekend. Although sustained 20-foot winds will generally remain
under 15 mph, gusts to around 25 mph may occur each afternoon.
Temperatures closer to normals today but will quickly heat back up
Wednesday and beyond, with near record highs returning Friday into
the weekend. Valley min RH readings will generally range between 20-
30% today with conditions drying out to 10-20% for Wednesday and
beyond.

&&

.PREV DISCUSSION...Skies are beginning to clear across southeast
Arizona with PWAT values ranging from 1.0"-1.4". The inverted trough
that helped storms out today is now to the north with high pressure
centered over Texas. Storms will likely struggle today thanks to
subsidence in the wake of the trough and slightly drier air moving
in. The HREF and other CAMs show minimal convection today with maybe
just a few weak short-lived isolated cells. Nothing like has
happened the past few days. High temperatures will top out a couple
degrees above normal.

Wednesday and Thursday look to be a bit more active than today with
just enough moisture for isolated storms mainly south and east of
Tucson. Main threats with any of these storm will be strong outflow
winds. After Thursday southeast Arizona really begins to dry out
with PWAT values dropping down to 1.1" or less through the weekend.
This is a result of high pressure moving back west over Arizona and
northern Mexico cutting moisture transport and warming the mid-
levels. Moisture values will be much below normal for this time of
year which could lead to a complete lack of thunderstorms Friday
through the weekend. Or if any form they would be short-lived and
mainly confined to the international border or higher terrain.

The main story will be the return of excessive heat Friday into the
weekend. During this time temperatures will likely be at or near
record levels. Friday into Sunday Tucson International Airport will
have a 44%-54% chance to hit 110 degrees or higher with the best
chance Saturday. Because of this and in coordination with PSR an
Excessive Heat Watch is in effect Friday through Sunday for portions
of Pima, Pinal, Santa Cruz, Graham, and Greenlee Counties.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Friday morning through Sunday evening
for AZZ502>506-509.

&&

Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson

In the hours before

Local storm report, Aug 1, 7:24 AM MST, 2 hours 36 minutes before

Preliminary Local Storm Report...Corrected
National Weather Service Tucson AZ
724 AM MST Tue Aug 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0552 PM     Tstm Wnd Gst     6 SW Tucson             32.13N 110.95W
07/31/2023  M58 MPH          Pima               AZ   ASOS

            Corrects previous tstm wnd gst report from 6
            SW Tucson. ASOS station KTUS Tucson
            International Airport.

&&

KD

Local storm report, Aug 1, 8:15 AM MST, 1 hour 45 minutes before

Preliminary Local Storm Report
National Weather Service Tucson AZ
815 AM MST Tue Aug 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0815 PM     Flash Flood      10 SSW Oro Valley       32.29N 111.04W
07/31/2023                   Pima               AZ   Broadcast Media

            Silverbell Rd south of Camino Del Cerro.

&&

KD

Local storm report, Aug 1, 8:37 AM MST, 1 hour 23 minutes before

Preliminary Local Storm Report
National Weather Service Tucson AZ
837 AM MST Tue Aug 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0715 PM     Tstm Wnd Dmg     6 SE Marana             32.35N 111.11W
07/31/2023                   Pima               AZ   Public

            Trees down blocking Silverbell Rd. north of
            Cortaro Farms Rd. reported on social media.
            Time estimated from radar.

&&

KD

Local storm report, Aug 1, 9:56 AM MST, 4 minutes before

Preliminary Local Storm Report
National Weather Service Tucson AZ
956 AM MST Tue Aug 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0640 PM     Tstm Wnd Dmg     11 SW Tucson            32.09N 111.02W
07/31/2023                   Pima               AZ   County Official

            Power poles down causing closure of Mission
            Rd. south of Campus Dr. Time estimated from
            radar.

0800 PM     Flash Flood      8 WSW Tucson            32.14N 111.02W
07/31/2023                   Pima               AZ   County Official

            Mission Rd. between Valencia and Drexel
            closed due to flooding.

&&

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

3 heat. Local standard time, as filed.

Heat, Tucson Metro Area

When: August 1, 10:00 AM MST to August 3, 8:00 PM MST
Where: Tucson Metro Area forecast zone
Deaths: 4 direct, 5 indirect
Reported by: County Official
Coordinates: 32.097, -111.790 (the zone’s center; the record gives no point)

Hot temperatures 2 to 6 degrees above normal caused the Moderate Heat Risk category to be reached in Tucson where temperatures topped out between 101 and 105 degrees. The Pima County Medical Examiner determined heat to be the primary cause of death for four individuals in the Tucson Metro area (two indoors with A/C units turned off and two others outdoors). Heat was determined to be a contributing factor in the deaths of five other individuals (two indoors with nonfunctioning A/C units but complicating factors of other health issues; one in a vehicle with other health issues; and two outdoors with complicating factors of drug toxicity).

Heat, Tohono O Odham Nation

When: August 1, 10:00 AM MST to 8:00 PM MST
Where: Tohono O Odham Nation forecast zone
Deaths: 1 direct, 0 indirect
Reported by: County Official
Coordinates: 32.501, -111.567 (the zone’s center; the record gives no point)

Hot temperatures around 5 degrees above normal, around 103 degrees, caused the Moderate Heat Risk category to be reached on the Tohono O'odham Nation on August 1. The Pima County Medical Examiner determined heat to be the primary cause of death for one individual found in the desert near Sells.

Heat, Eastern Cochise County Below 5000 Feet

When: August 1, 10:00 AM MST to 8:00 PM MST
Where: Eastern Cochise County Below 5000 Feet forecast zone
Deaths: 1 direct, 0 indirect
Reported by: County Official
Coordinates: 31.880, -109.751 (the zone’s center; the record gives no point)

Hot temperatures 4 to 6 degrees above normal caused the Moderate Heat Risk category to be reached in eastern Cochise County where temperatures topped out around 100 degrees. The Pima County Medical Examiner determined heat to be the primary cause of death for one individual whose electricity and A/C unit was off in the community of Cochise.

The people who died

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, Tucson Metro Area	2023-08-01	62	Male	Mobile/Trailer Home	Direct
Heat, Tucson Metro Area	2023-08-03	63	Male	Mobile/Trailer Home	Direct
Heat, Tucson Metro Area	2023-08-02	83	Female	Outside/Open Areas	Direct
Heat, Tucson Metro Area	2023-08-03	62	Male	Outside/Open Areas	Direct
Heat, Tucson Metro Area	2023-08-02	53	Male	Outside/Open Areas	Indirect
Heat, Tucson Metro Area	2023-08-03	49	Male	Outside/Open Areas	Indirect
Heat, Tucson Metro Area	2023-08-01	71	Female	Permanent Home	Indirect
Heat, Tucson Metro Area	2023-08-03	76	Male	Permanent Home	Indirect
Heat, Tucson Metro Area	2023-08-02	74	Female	Vehicle/Towed Trailer	Indirect
Heat, Tohono O Odham Nation	2023-08-01	46	Male	Outside/Open Areas	Direct
Heat, Eastern Cochise County Below 5000 Feet	2023-08-01	62	Male	Mobile/Trailer Home	Direct

What these are

Heat: Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Arizona in 2023 Every state in 2023 This day in weather history Warnings in Arizona, August 2023

Sources

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: 1134748, 1134749, 1134750.