Alert archive / Arizona / Flash Flood Warnings in 2026

Flash Flood Warning 41, NWS Phoenix, AZ

August 12, 2026Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 12, 2026, 9:38 PM MST for Maricopa County, Arizona. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 12, 2026, 9:38 PM MST (04:38 UTC)
Expired
Aug 13, 2026, 12:30 AM MST
In force
3 hr
Issued by
NWS Phoenix, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 102 km from the middle of the area, began a volume at 04:42 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 12, 11:23 PM MSTFLASH FLOOD15 Ssw Buckeye, AZ***DELAYED REPORT*** Old US Highway 80 and Patterson Rd were closed due to flooding at the low water crossings through Rainbow Wash. The FCDMC Rainbow Wash stream gage exceeded Alarm stage, peaking at 1.58 ft or 729 cfs.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this flash flood warning; the first came 105 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 4.6 hours before the alert went out and 77 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Phoenix, AZ at 00:00Z on 2026-08-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 559 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 00:00Z on 2026-08-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
559 J/kg
Mixed-layer CIN
-32 J/kg
Mixed-layer LCL
2150 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
36 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

863 
WGUS55 KPSR 130438
FFWPSR
AZC013-130730-
/O.NEW.KPSR.FF.W.0041.260813T0438Z-260813T0730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
938 PM MST Wed Aug 12 2026

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Maricopa County in south central Arizona...

* Until 1230 AM MST.

* At 938 PM MST, Doppler radar and automated rain gauges indicated
  between 0.5 and 1.5 inches of rain have fallen. A Maricopa County
  Flood Control District streamflow gauge reached alarm stage at
  Rainbow Wash. Additional rainfall amounts up to 0.25 inches are
  possible in the warned area. Flash flooding is ongoing or expected
  to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms producing
           flash flooding.

  SOURCE...Radar and automated gauges.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Buckeye and Painted Rock Dam. Low water crossings downstream of
  Rainbow Wash along Old US 80 and Patterson Road.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 3321 11295 3316 11289 3314 11271 3316 11260
      3318 11254 3329 11258 3329 11284

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

TW
1 follow-up statement
754 
WGUS75 KPSR 130726
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1226 AM MST Thu Aug 13 2026

AZC013-130736-
/O.EXP.KPSR.FF.W.0041.000000T0000Z-260813T0730Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1226 AM MST Thu Aug 13 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 1230 AM MST EARLY THIS MORNING
FOR MARICOPA COUNTY...

The heavy rain has ended. Flood waters have receded. Flooding is no
longer expected to pose a threat. Please continue to heed remaining
road closures.

&&

LAT...LON 3321 11295 3316 11289 3314 11271 3316 11260
      3318 11254 3329 11258 3329 11284

$$

RW

What forecasters said that day

The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Aug 12, 5:00 PM MST, 4 hours 38 minutes earlier. Its key messages:

  • Better moisture and more favorable conditions for showers and storms are expected by this evening, lasting into Thursday morning.
  • A Flood Watch has been issued for the high terrain across central and portions of eastern Arizona from late afternoon through tonight. Locally heavy rainfall will also be possible into the south-central Arizona lower deserts.
  • Near to below normal temperatures are forecast through Friday before warming back up over the weekend into early next week.
Area forecast discussion, Aug 12, 5:00 PM MST, 4 hours 38 minutes before
Area Forecast Discussion
National Weather Service Phoenix AZ
500 PM MST Wed Aug 12 2026

.UPDATE...00Z Aviation Discussion

&&

.KEY MESSAGES...

- Better moisture and more favorable conditions for showers and
  storms are expected by this evening, lasting into Thursday
  morning.

- A Flood Watch has been issued for the high terrain across
  central and portions of eastern Arizona from late afternoon
  through tonight. Locally heavy rainfall will also be possible
  into the south-central Arizona lower deserts.

- Near to below normal temperatures are forecast through Friday
  before warming back up over the weekend into early next week.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
This afternoon and tonight continue to point towards being quite
busy, with the main forecast concern being the potential for
heavy rainfall stemming from a high likelihood of localized
rainfall rates of 1-2"/hr and training of storms in the higher
terrain areas, as depicted by CAMs. Due to this a Flood Watch has
been issued for all of Gila County as well as over far northern
Pinal and northeast Maricopa Counties from late this afternoon
through tonight.

The upper level pattern shows the Desert SW sandwiched between
the subtropical ridge, that has moved into Texas, and the upper
level trough along the California coast line. This set up has
promoted southerly flow aloft into our region and will be able to
tap into plenty of moisture from a decaying MCV from earlier this
morning over the Sonoran Desert. Current meso analysis along with
this morning's 12Z sounding have PWATs near 1.7" and closer to
1.8-1.9" in the western lower deserts. The morning sounding also
revealed a decent amount of MUCAPE, with most of the CIN near the
surface. The 12Z convective temperature was only 95F, and with an
afternoon high expected to to climb near to slightly above 100
degrees in the lower deserts, convection is likely to break
through any lingering surface level CIN. Model soundings are
forecasting MUCAPEs mainly between 750-1500 J/kg in the lower
deserts and will steadily diminish through the late evening hours,
into the overnight period, making late this afternoon and into the
evening hours the expected peak time for storms, similar to earlier
this week. However, CAMs still show storms likely continuing past
midnight, mostly in the higher terrain, while the lower deserts, to
include La Paz County, have the highest chance, 50-70%, of showers
during the evening hours, as mentioned previously. Additional
isolated showers and thunderstorms will again be possible Thursday
afternoon, but with the atmosphere drying out and forcing waining
there will be a significantly lower chance of localized heavy
rainfall.

Temperatures will be quite pleasant compared to what is normally
expected for mid August with afternoon highs mostly in the high
90s to low 100s, with many areas struggling to reach 100F. The
only exception will be areas in the western lower deserts where
temperatures will range in the low to mid 100s, keeping pockets of
Moderate HeatRisk in place. Otherwise, widespread Minor HeatRisk
is expected through the end of the week.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Dry air will continue to spread northeastward through Arizona on
Friday with low level mixing ratios dropping to around 8 g/kg over
the lower deserts to 9-10 g/kg over the eastern Arizona high
terrain. These moisture levels during the summer monsoon season
typically prohibit convection across the area with at most a
10-20% chance of isolated showers or weak storms across the far
eastern Arizona high terrain. However, even with the drying
conditions surface dew points well into the 50s will still keep
that slight muggy feeling in the air. The trough will continue to
influence the region through Friday keeping temperatures a few
degrees below normal under partly cloudy skies.

Saturday looks to be quite similar to Friday with periods of
higher clouds persisting, but temperatures will begin to tick
upward again as the subtropical high begins to nudge back into our
region. Guidance shows H5 heights gradually rising into a
592-595dm range by early next week, or back to around the 90th
percentile of climatology. Moisture levels look to stay fairly
steady for the rest of the weekend into early next week keeping at
most low grade monsoon storm chances in place. The increased
heights and somewhat dry conditions will help to push daytime
highs to above normal by Monday with readings right around 110
degrees for next Monday and Tuesday.

&&

.AVIATION...Updated at 0000Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Main aviation concern during the TAF period will be convective
activity around metro terminals this evening, and potentially once
again overnight. First SHRA/TSRA will occur between now and around
05Z-06Z, with the second, but less certain window, being between
07Z-12Z. Main impacts will be sub-VFR VIS and gusty and erratic
winds. How strong winds become remain uncertain, but there is
currently not a strong signal indicating gusts will exceed 30 kt.
Convective activity should begin to clear the area after 12Z at
the latest, but lingering SHRA for a few hours beyond that cannot
be completely ruled out. Outside of the variability and
uncertainty of the convective timeframe, winds are expected to
follow familiar diurnal trends.

Southeast California/Southwest Arizona including KIPL and KBLH:
Main aviation concern will be SHRA/TSRA this evening into early
tonight. Impacts associated with convective activity will be
reduced VIS and winds exceeding 30 kt at times. Activity at KIPL
will end within in the next few hours, but KBLH could see
lingering activity until around 06Z tonight, potentially
resulting in numerous strong outflows. Conditions through the
remainder of the night into Thursday morning should be much
calmer, with familiar diurnal wind trends and drier conditions
returning.

&&

.FIRE WEATHER...
Elevated humidity levels, cooler temperatures, and good chances
for wetting rains are anticipated through Thursday morning over
at least the eastern districts. The best rain chances will be
during the evening and overnight hours tonight with lingering
chances through Thursday afternoon. Afternoon MinRHs will range
between 25-35% across the lower deserts and 40-50% for the
eastern high terrain, while overnight recoveries will remain
excellent. Winds will predominately be out of the south southwest
much of the period with the exception of any modest outflows from
thunderstorm activity. Drying conditions will move into the
region Friday and through the weekend dropping MinRHs to between
15-25% while temperatures gradually rise back to above normal.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through late tonight for AZZ541-545-547-549-552-
     555>558-560>563.

CA...None.
&&

SHORT TERM...Ryan/Kuhlman
LONG TERM...Kuhlman
AVIATION...RW
FIRE WEATHER...Kuhlman

In the hours before

Local storm report, Aug 12, 7:41 PM MST, 1 hour 57 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
741 PM MST Wed Aug 12 2026

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

0550 PM     Tstm Wnd Dmg     4 W Blythe              33.61N 114.66W
08/12/2026                   Riverside          CA   Dept of Highways

            Report of at least one semi truck on its
            side and power lines down in the road.
            Nearby Blythe Airport measured a 53 mph wind
            gust around the same time as these report.

&&

SB
Local storm report, Aug 12, 7:59 PM MST, 1 hour 39 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
759 PM MST Wed Aug 12 2026

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

0654 PM     Flash Flood      5 N Quartzsite          33.74N 114.22W
08/12/2026                   La Paz             AZ   Dept of Highways

            Reports of water flowing over SR-95.

&&

SB
Local storm report, Aug 12, 8:32 PM MST, 1 hour 6 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
832 PM MST Wed Aug 12 2026

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

0643 PM     Tstm Wnd Dmg     2 NW Gilbert            33.37N 111.81W
08/12/2026                   Maricopa           AZ   Utility Company

            Report of power lines down.

&&

SB
Local storm report, Aug 12, 8:33 PM MST, 1 hour 5 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
833 PM MST Wed Aug 12 2026

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

0643 PM     Tstm Wnd Dmg     2 NNW Gilbert           33.38N 111.80W
08/12/2026                   Maricopa           AZ   Utility Company

            Report of power lines down.

&&

SB
Local storm report, Aug 12, 8:34 PM MST, 1 hour 4 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
834 PM MST Wed Aug 12 2026

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

0713 PM     Tstm Wnd Dmg     2 ESE Mesa              33.41N 111.79W
08/12/2026                   Maricopa           AZ   Utility Company

            Report of power lines down.

&&

SB
Local storm report, Aug 12, 8:52 PM MST, 46 minutes before
Preliminary Local Storm Report
National Weather Service Phoenix AZ
852 PM MST Wed Aug 12 2026

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

0420 PM     Tstm Wnd Dmg     2 N Holtville           32.84N 115.38W
08/12/2026                   Imperial           CA   Dept of Highways

            Large tree down in road.

&&

SB

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 12, 5:05 PM MSTSevere Thunderstorm WarningPSRLa Paz40 min
Aug 12, 5:13 PM MSTSpecial Weather StatementPSRMaricopa32 min
Aug 12, 5:20 PM MSTSevere Thunderstorm WarningPSRMaricopa40 min
Aug 12, 5:24 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz7 hr
Aug 12, 5:45 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz3 hr
Aug 12, 5:48 PM MSTSevere Thunderstorm WarningPSRMaricopa27 min
Aug 12, 6:11 PM MSTSpecial Weather StatementPSRLa Paz, Yuma2 hr
Aug 12, 6:19 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz6 hr
Aug 12, 6:25 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz5 hr
Aug 12, 6:26 PM MSTSevere Thunderstorm WarningPSRLa Paz34 min
Aug 12, 6:40 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Aug 12, 6:43 PM MSTSevere Thunderstorm WarningPSRMaricopa32 min
Aug 12, 7:08 PM MSTSevere Thunderstorm WarningPSRLa Paz37 min
Aug 12, 7:24 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz5 hr
Aug 12, 7:45 PM MSTSevere Thunderstorm WarningPSRLa Paz45 min
Aug 12, 8:19 PM MSTAreal Flood AdvisoryPSRMaricopa79 min
Aug 12, 9:11 PM MSTAreal Flood AdvisoryPSRLa Paz, Maricopa3 hr
Aug 12, 9:56 PM MSTSpecial Weather StatementPSRLa Paz34 min
Aug 12, 10:11 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa3 hr
Aug 12, 10:36 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz3 hr
Aug 12, 10:48 PM MSTSpecial Weather StatementPSRLa Paz42 min
Aug 12, 11:33 PM MSTExtreme Heat WatchPSRLa Paz, Maricopa, Pinal, Yuma59 hr
Aug 13, 12:10 AM MSTAreal Flood WarningPSRLa Paz6 hr
Aug 13, 4:08 PM MSTSpecial Weather StatementPSRMaricopa37 min
Aug 13, 4:24 PM MSTSevere Thunderstorm WarningPSRMaricopa, Pinal36 min
Aug 13, 4:40 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Aug 13, 4:46 PM MSTSpecial Weather StatementPSRMaricopa29 min
Aug 13, 4:54 PM MSTSpecial Weather StatementPSRMaricopa36 min

Nearby

Flash Flood Warnings in Arizona, 2026Every flash flood warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.