Flash Flooding in Arizona, July 28, 2022

Name: Flash Flooding in Arizona, July 28, 2022
Start: 2022-07-28T12:00
End: 2022-07-28T23:00
Location: Arizona

July 28, 2022 · NWS PSR · 7 events in 4 counties and zones

0 inches), moderate to strong instability (SBCAPE 2000 J/KG), very slow steering flow and an upper-level disturbance resulted in a very conducive environment for the generation of thunderstorms producing very heavy rainfall activity across portions of south-central and southwestern Arizona, resulting in flash flooding. Activity first developed across the foothills and higher terrain of Eastern…

Where it happened

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The toll

Deaths: 0
Injuries: 0
Property damage: $1.0 million
Crop damage: None recorded
Events: 7

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 PSR wrote it up.

The combination of near record moisture content (PWATs 1.8-2.0 inches), moderate to strong instability (SBCAPE 2000 J/KG), very slow steering flow and an upper-level disturbance resulted in a very conducive environment for the generation of thunderstorms producing very heavy rainfall activity across portions of south-central and southwestern Arizona, resulting in flash flooding. Activity first developed across the foothills and higher terrain of Eastern Maricopa and Gila Counties during the late morning-early afternoon hours. Another area of thunderstorms developed over northwestern Arizona during the mid-late afternoon hours and move southward towards La Paz County into the evening hours. One of the areas severely hit by flash flooding was Apache Junction, AZ. Weekes Wash, which runs through the town, went of out of its banks, causing widespread flooding impacts across the city. Flooding also took place from drainage that occurred off the Goldfield and Superstitions Mountains.

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 Phoenix, AZ wrote its last area forecast discussion before the first event at Jul 28, 10:52 AM MST, 1 hour 8 minutes earlier.

Area forecast discussion, Jul 28, 10:52 AM MST, 1 hour 8 minutes before

Area Forecast Discussion
National Weather Service Phoenix AZ
1052 AM MST Thu Jul 28 2022

..UPDATE...18z Aviation Discussion...

&&

.SYNOPSIS...
A flood watch remains in effect for Phoenix and over higher
terrain locations north and east of Phoenix through Thursday night.
An abundance of moisture will allow any showers and storms that
develop to produce heavy rainfall. The highest chances for showers
and storms through the weekend will be over higher terrain areas,
but daily rain chances of 20 to 40 percent extend into the
Phoenix area. High temperatures will continue to run below normal
over the majority of the area with highs from the upper nineties
in the Phoenix area to just over 100 degrees across the western
deserts.

&&

.DISCUSSION...
The Desert Southwest continues to see deep monsoonal moisture over
the bulk of the region and this should persist through at least
the weekend. PWATs exceeding 90% of climo cover the majority
Arizona (except for eastern Arizona) with the highest anomalous
PWATs (99% of climo) over north central Arizona. The problem with
having this much moisture is it means the atmosphere is having a
difficult time destabilizing due to abundant cloud cover. A good
trigger for organized convection has been lacking and this will
overall continue to be an issue over the next several days.

KFGZ and KTWC 00Z raobs show a moist atmosphere through the
entire column with MUCAPE around 1000 J/kg, but overall very weak
winds aloft. Latest HRRR shows expanding shower coverage over
south-central Arizona through sunrise. Although lapse rates are
quite poor, there is a general lack of CIN through much of the
column and it would not take much to trigger shower and isolated
thunderstorm activity early this morning. It is becoming
increasingly evident that the best chance for rain today over the
lower deserts is likely going to be before noon as a weakening
vort center is now entering southeast Arizona. This compact
disturbance is likely to bring just enough forced ascent for
at least scattered showers and isolated thunderstorms across
Pinal and Maricopa Counties this morning. By this afternoon, the
vort center is forecast to move well south of Phoenix with
activity diminishing over the lower deserts. Shower and
thunderstorm potential then will become focused over the high
terrain north and east of Phoenix this afternoon into early this
evening. Heavy rainfall and potential localized flooding will
continue to be the main forecast concern with any shower and
thunderstorm activity today. However, forecast CAPE over
southwest Arizona and even into portions of south-central Arizona
is quite low for today and Friday. WPC's Day 1 & 2 EROs now has
the slight risk pulled farther to the east where the better
instability resides. As a result, we have cancelled the Flood
Watch for La Paz Co. and western Maricopa Co.

The weather pattern changes very little through the weekend with
deep moist southeasterly flow persisting over much of the region.
The moisture will be available for shower and thunderstorm
activity through at least the weekend, but there are no
discernible disturbances for triggers and the flow aloft will
remain weak. Overall, convection is likely to remain favored more
over the high terrain through the weekend with more
isolated/scattered coverage over the lower deserts. Due to
persistent high moisture content, temperatures should on average
remain several degrees below normal across southern Arizona to a
couple degrees below normal over southeast California. The sub-
tropical high center is favored to finally shift back to the east
at some point early next week which will may lead to some modest
drying across the region. This is mostly reflected in lower NBM
PoPs across the western deserts by next Tuesday, but 40-60% PoPs
stick around for the eastern Arizona high terrain. If the
atmosphere does dry out a little next week, it will likely become
more conducive for more organized storm outflows and stronger wind
potential over the area.

&&

.AVIATION...Updated at 1750z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Widespread showers have mainly stayed west of the terminals, but
now in more unstable air to the west, isolated storms were
rapidly developing. Anticipating VCTS for all terminals into early
afternoon, through 21-22z timeframe. Impacts would be mainly
brief heavy rainfall. After that, we are likely to see a break
into the evening for rainfall and storms. Winds will generally be
westerly through early evening before shifting back around to the
east. Some erratic winds around storms through early afternoon but
not expecting anything above 25kts. Cloud cover will continue to
be sct/bkn in mid levels with high level bkn clouds persisting.
Have introduced some VCSH again for the morning hours. Guidance
continues to hint at this occurring again in some areas.

Southeast California/Southwest Arizona including KIPL and KBLH:
IPL: Generally SE winds continue through the period with SCT/BKN
mid and upper cloud cover.

BLH: South winds become more SE by early evening. Slightly better
chance (10-20%) in this area for a shower or storm today - but
still too low confidence to include VC in TAF. BKN mid level
clouds are expected.

&&

.FIRE WEATHER...
Abundant monsoonal moisture will persist across the area for the
foreseeable future keeping the overall fire threat low. The main
threat through at least the weekend will be daily chances for
thunderstorms, particularly across the high terrain. A flood
watch is also in effect for areas from Phoenix eastward through
Thursday tonight. MinRH values will remain quite high, ranging
from 25-30% over SW AZ and SE CA to 30-45% near Phoenix and points
eastward. Wetting rain chances through the weekend range from
10-30% over the Arizona lower deserts to upwards of 50-70% over
high terrain areas. Winds will generally remain light, save for
brief gusts near any stronger storms.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through late tonight for AZZ537-540>558-560>563.

CA...None.
&&

DISCUSSION...Kuhlman
AVIATION...Heil/Frieders
FIRE WEATHER...Kuhlman

The radar

The Phoenix radar (KIWA), 21 km away, was scanning. The volume nearest the first event began at 19:01 UTC.

Open the radar archive at this moment

Event by event

7 flash flood. Local standard time, as filed.

Flash Flood, Pinal

When: July 28, 12:00 PM MST to 5:00 PM MST
Where: Pinal County, 5.14 mi NW of Apache Jct to 4.73 mi NNW of Goldfield
Cause: Heavy Rain
Property damage: $1.0 million
Reported by: County Official
Coordinates: 33.472, -111.614

Between 1 and 3 inches of rain fell within 1-2 hours across Apache Junction and the adjacent higher terrain north and east of the city, towards the Goldfield and Superstitions mountains. Water from those mountains drained down towards the area washes, including Weekes Wash, which runs through the city. Numerous roads were flooded and damaged along with multiple water rescues taking place of residents in homes that either were surrounded with water or had water inside them. One of the more dramatic water rescues occurred when a woman had to be rescued from her vehicle that was swept away by the flood waters of Weekes Wash and traveled half a mile downstream before encountering a box culvert. No injuries or fatalities were reported.

Flash Flood, Gila

When: July 28, 12:15 PM MST to 2:15 PM MST
Where: Gila County, 1.35 mi SW of Miami to 1.34 mi SW of Miami
Cause: Heavy Rain
Reported by: Social Media
Coordinates: 33.387, -110.888

A video posted on social media showed strong flow moving along the Bloody Tanks Wash, resulting a street crossing the wash near Mackey Camp to be completely impassable. No damages or injuries were reported.

Flash Flood, Gila

When: July 28, 12:30 PM MST to 2:30 PM MST
Where: Gila County, 0.71 mi SW of Miami to 0.51 mi ESE of Miami
Cause: Heavy Rain
Reported by: Social Media
Coordinates: 33.393, -110.879

Social media video showed Bloody Tanks Wash in major elevated stage as it was flowing down the city of Miami. No damages or injuries were reported.

Flash Flood, Maricopa

When: July 28, 12:30 PM MST to 3:30 PM MST
Where: Maricopa County, 7.42 mi SW of Tortilla Flat to 6.31 mi SW of Tortilla Flat
Cause: Heavy Rain
Reported by: Department of Highways
Coordinates: 33.463, -111.481

The Arizona Department of Transportation reported SR 88 was closed due to flooding between milepost 201 and 205. No damages or injuries were reported.

Flash Flood, Maricopa

When: July 28, 1:00 PM MST to 3:00 PM MST
Where: Maricopa County, 5.83 mi NE of Skyway Vlg to 5.77 mi NE of Skyway Vlg
Cause: Heavy Rain
Property damage: $2,000
Reported by: Park/Forest Service
Coordinates: 33.556, -111.544

Water Users Recreation Site just downstream of Saguaro Lake was closed due to flash flooding and debris deposited into the Lower Salt River, making the water unsafe for public use. No injuries were reported.

Flash Flood, Maricopa

When: July 28, 1:50 PM MST to 3:50 PM MST
Where: Maricopa County, 10.09 mi WSW of Sunflower to 8.52 mi W of Sunflower
Cause: Heavy Rain
Property damage: $2,000
Reported by: Park/Forest Service
Coordinates: 33.841, -111.642

North Lake Rd along Bartlett Lake was closed due to flooding and debris making the road impassable to vehicular traffic. No injuries were reported.

Flash Flood, La Paz

When: July 28, 9:00 PM MST to 11:00 PM MST
Where: La Paz County, 1.45 mi N of Quartzite to 0.27 mi NE of Quartzsite Arpt
Cause: Heavy Rain
Reported by: Law Enforcement
Coordinates: 33.691, -114.231

La Paz County Dispatch reported the following roadways were closed due to flooding from water overflowing from Tyson Wash: Tyson Street, North Washington Avenue from Quail Trail to Kenoyer Streets, and Plymouth Road. at Mockingbird St. No damages or injuries were reported.

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

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

The same day elsewhere

Every storm in Arizona in 2022 Every state in 2022 This day in weather history Warnings in Arizona, July 2022

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 2026-09-30. Each event’s entry at NCEI: 1048620, 1048628, 1048627, 1048634, 1048629, 1048633, 1048636.