Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 62, NWS Phoenix, AZ

July 22, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 22, 2021, 9:49 PM MST for Maricopa County, Arizona. It was in force for 4 hr. 2 reports 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
Jul 22, 2021, 9:49 PM MST (04:49 UTC)
Expired
Jul 23, 2021, 2:00 AM MST
In force
4 hr
Issued by
NWS Phoenix, AZ
Area
Storm-based polygon
Flood severity
None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 58 km from the middle of the area, began a volume at 04:49 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
Jul 22, 10:14 PM MSTFLASH FLOOD4 S Deer Valley, AZVEHICLE TRAPPED IN FLOOD WATER AT I17/THUNDERBIRD. PORTIONS OF THE ROAD AND HIGHWAY WERE CLOSED DUE TO FLOODING.
Jul 22, 10:21 PM MSTFLASH FLOOD3 S Deer Valley, AZADOT REPORTED HIGHWAY RAMPS AT I17/GREENWAY WERE COMPLETELY UNDERWATER.

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

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 4.8 hours before the alert went out and 29 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 2021-07-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1155 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 00:00Z on 2021-07-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -25 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
1155 J/kg
Mixed-layer CIN
-46 J/kg
Mixed-layer LCL
2803 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
-25 m²/s²
0-3 km storm-relative helicity
-22 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

456 
WGUS55 KPSR 230449
FFWPSR
AZC013-230900-
/O.NEW.KPSR.FF.W.0062.210723T0449Z-210723T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
949 PM MST Thu Jul 22 2021

The National Weather Service in Phoenix has issued a

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

* Until 200 AM MST.

* At 949 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Phoenix, Glendale, Peoria, Sun City, Arrowhead Mall, Metro Center 
  Mall, Downtown Peoria, Deer Valley Airport and North Mountain Park.

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 3373 11230 3373 11214 3373 11211 3373 11207
      3373 11204 3374 11202 3373 11201 3371 11204
      3367 11203 3365 11204 3364 11204 3359 11205
      3357 11208 3355 11207 3355 11221 3356 11229

FLASH FLOOD...RADAR INDICATED

$$

AD
3 follow-up statements
662 
WGUS75 KPSR 230611
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1111 PM MST Thu Jul 22 2021

AZC013-230900-
/O.CON.KPSR.FF.W.0062.000000T0000Z-210723T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1111 PM MST Thu Jul 22 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 2 AM MST FRIDAY FOR 
MARICOPA COUNTY...

At 1111 PM MST, Gauge reports indicated thunderstorms produced heavy 
rain across the warned area. Between 0.5 and 1 inch of rain has 
fallen. Flash flooding is already occurring in some places.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Gauges reported.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Phoenix, Glendale, Peoria, Sun City, Arrowhead Mall, Metro Center 
  Mall, Downtown Peoria, Deer Valley Airport and North Mountain Park.

Multiple I-17 underpasses are submerged. 
The ACDC at 43rd Ave has reached alarm stage. 

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 3373 11230 3373 11214 3373 11211 3373 11207
      3373 11204 3374 11202 3373 11201 3371 11204
      3367 11203 3365 11204 3364 11204 3359 11205
      3357 11208 3355 11207 3355 11221 3356 11229

FLASH FLOOD...GAUGE INDICATED

$$

AD
293 
WGUS75 KPSR 230744
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1244 AM MST Fri Jul 23 2021

AZC013-230900-
/O.CON.KPSR.FF.W.0062.000000T0000Z-210723T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1244 AM MST Fri Jul 23 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 2 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 1244 AM MST, Runoff from recent thunderstorms continues. Some 
roads remain flooded.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public reported.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Phoenix, North Mountain Park and Metro Center Mall.

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.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3363 11212 3363 11210 3364 11207 3364 11205
      3364 11204 3359 11206 3357 11208 3356 11208
      3356 11213

FLASH FLOOD...OBSERVED

$$

AD
668 
WGUS75 KPSR 230855
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
155 AM MST Fri Jul 23 2021

AZC013-230905-
/O.EXP.KPSR.FF.W.0062.000000T0000Z-210723T0900Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
155 AM MST Fri Jul 23 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 2 AM MST EARLY THIS MORNING 
FOR MARICOPA COUNTY...

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

A Flash Flood Watch remains in effect until 1100 PM MST Saturday for 
a portion of south central Arizona.

LAT...LON 3363 11212 3363 11210 3364 11207 3364 11205
      3364 11204 3359 11206 3357 11208 3356 11208
      3356 11213

$$

18

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 22, 5:42 PM MSTSpecial Weather StatementPSR48 min
Jul 22, 6:11 PM MSTAreal Flood AdvisoryPSRMaricopa39 min
Jul 22, 6:31 PM MSTSpecial Weather StatementPSR59 min
Jul 22, 6:50 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Jul 22, 7:19 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Jul 22, 7:29 PM MSTSpecial Weather StatementPSR61 min
Jul 22, 7:40 PM MSTSevere Thunderstorm WarningPSRPinal35 min
Jul 22, 7:46 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Jul 22, 7:48 PM MSTDust Storm AdvisoryPSRMaricopa, Pinal27 min
Jul 22, 7:53 PM MSTSpecial Weather StatementPSRPinal37 min
Jul 22, 7:55 PM MSTAreal Flood AdvisoryPSRMaricopa, Pinal5 hr
Jul 22, 8:05 PM MSTSpecial Weather StatementPSRMaricopa25 min
Jul 22, 8:06 PM MSTFlash Flood Warning Considerable damage threatPSRPinal4 hr
Jul 22, 8:15 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Jul 22, 8:19 PM MSTSevere Thunderstorm WarningPSRMaricopa26 min
Jul 22, 8:29 PM MSTSpecial Weather StatementPSRPinal61 min
Jul 22, 8:39 PM MSTSpecial Weather StatementPSRMaricopa51 min
Jul 22, 8:52 PM MSTFlash Flood WarningPSRMaricopa4 hr
Jul 22, 8:56 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Jul 22, 9:28 PM MSTSpecial Weather StatementPSRMaricopa47 min
Jul 22, 9:40 PM MSTFlash Flood WarningPSRMaricopa3 hr
Jul 22, 9:45 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa3 hr
Jul 22, 9:54 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa4 hr
Jul 22, 10:07 PM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa, Pinal4 hr
Jul 22, 10:16 PM MSTAreal Flood AdvisoryPSRPinal3 hr
Jul 22, 10:57 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa113 min
Jul 22, 11:15 PM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Jul 22, 11:29 PM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Jul 22, 11:43 PM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Jul 23, 4:37 AM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Jul 23, 8:37 AM MSTAreal Flood WarningPSRGila4 days
Jul 23, 9:07 AM MSTSpecial Weather StatementPSR38 min
Jul 23, 9:30 AM MSTSpecial Weather StatementPSR30 min
Jul 23, 9:55 AM MSTAreal Flood WarningPSRMaricopa6 hr
Jul 23, 9:58 AM MSTSpecial Weather StatementPSR32 min
Jul 23, 10:31 AM MSTSpecial Weather StatementPSR29 min
Jul 23, 10:53 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Jul 23, 11:11 AM MSTSpecial Weather StatementPSR34 min
Jul 23, 11:46 AM MSTSpecial Weather StatementPSR29 min
Jul 23, 12:02 PM MSTSpecial Weather StatementPSR28 min
Jul 23, 12:09 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Jul 23, 12:30 PM MSTSpecial Weather StatementPSR30 min
Jul 23, 12:53 PM MSTSpecial Weather StatementPSR37 min
Jul 23, 1:01 PM MSTSpecial Weather StatementPSR29 min
Jul 23, 1:11 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Jul 23, 1:34 PM MSTSpecial Weather StatementPSR26 min
Jul 23, 2:25 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Jul 23, 3:20 PM MSTAreal Flood WarningPSRMaricopa9 hr
Jul 23, 4:00 PM MSTAreal Flood WarningPSRMaricopa8 hr
Jul 23, 4:02 PM MSTAreal Flood WarningPSRMaricopa8 hr

Nearby

Flash Flood Warnings in Arizona, 2021Every flash flood warning in 2021

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.