Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 77, NWS Phoenix, AZ

July 25, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 25, 2021, 9:56 AM MST for Maricopa County, Arizona. It was in force for 8 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: Jul 25, 2021, 9:56 AM MST (16:56 UTC)
Expired: Jul 25, 2021, 5:45 PM MST
In force: 8 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), 67 km from the middle of the area, began a volume at 16:55 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

Time	Report	Where	Remark
Jul 25, 10:05 AM MST	FLASH FLOOD	6 N Deer Valley, AZ	* DELAYED REPORT * FCDMC SONORAN WASH #65907 REACHED AND EXCEEDED BANK FULL WITH FLOOD WATERS LIKELY IMPACTING UNBRIDGED CROSSING AT DIXILETA DR. ONE MILE DOWNSTREAM OF GAUGE.

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

The nearest sounding before it

Flgstf/Belemont, AZ (KFGZ), launched 12:00Z, 4.9 hours before the alert went out and 167 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 4 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 803 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -30 m²/s²
0-3 km storm-relative helicity: 25 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

701 
WGUS55 KPSR 251656
FFWPSR
AZC013-252045-
/O.NEW.KPSR.FF.W.0077.210725T1656Z-210725T2045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
956 AM MST Sun Jul 25 2021

The National Weather Service in Phoenix has issued a

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

* Until 145 PM MST.

* At 956 AM MST, Doppler radar and automated rain gauges indicated 
  heavy rain falling near Interstate 17 and Loop 303 with flood 
  waters flowing through Sonoran Wash. Between 0.5 and 1.5 inches of 
  rain have fallen. Additional rainfall amounts of 0.5 to 1.5 inches 
  are possible in the warned area. Flash flooding is already 
  occurring.

  HAZARD...Life threatening flash flooding. Heavy rain 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...
  Phoenix, Glendale, New River, Cave Creek and Deer Valley Airport.

This includes the following highways...
	AZ Route 101 between mile markers 20 and 29.
	AZ Route 74 between mile markers 27 and 30.
	AZ Route 303 between mile markers 135 and 139.
	AZ Interstate 17 between mile markers 214 and 223.

This includes the following streams and drainages...
  Skunk Creek, Apache Wash, Cave Creek, New River, Deadman Wash and 
  North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3379 11221 3385 11217 3381 11199 3366 11201
      3364 11216 3371 11220

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

$$

SDB

4 follow-up statements

369 
WGUS55 KPSR 252032
FFWPSR
AZC013-252245-
/O.EXT.KPSR.FF.W.0077.000000T0000Z-210725T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
132 PM MST Sun Jul 25 2021

The National Weather Service in Phoenix has extended the

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

* Until 345 PM MST.

* At 132 PM MST, Doppler radar and automated rain gauges indicated 
  heavy rain falling in Sonoran Wash. Between 0.5 and 1.5 inches of 
  rain have fallen. Additional rainfall amounts up to 0.5 inches are 
  possible in the warned area. Flash flooding is already occurring.

  HAZARD...Life threatening flash flooding. Heavy rain 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...
  Phoenix, Glendale, New River, Cave Creek and Deer Valley Airport.

This includes the following highways...
	AZ Route 101 between mile markers 20 and 29.
	AZ Route 74 between mile markers 27 and 30.
	AZ Route 303 between mile markers 135 and 139.
	AZ Interstate 17 between mile markers 214 and 223.

This includes the following streams and drainages...
  Skunk Creek, Apache Wash, Cave Creek, New River, Deadman Wash and 
  North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3379 11221 3385 11217 3381 11199 3366 11201
      3364 11216 3371 11220

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

$$

INS

547 
WGUS55 KPSR 252237
FFWPSR
AZC013-260045-
/O.EXT.KPSR.FF.W.0077.000000T0000Z-210726T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
337 PM MST Sun Jul 25 2021

The National Weather Service in Phoenix has extended the

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

* Until 545 PM MST.

* At 337 PM MST, Doppler radar and automated rain gauges indicated 
  heavy rain falling in Sonoran Wash. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts up to 0.5 inches are 
  possible in the warned area. Flash flooding is already occurring.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar and automated gauges.

  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, New River, Cave Creek and Deer Valley Airport.

This includes the following highways...
	AZ Route 101 between mile markers 21 and 26.
	AZ Route 74 between mile markers 28 and 30.
	AZ Route 303 between mile markers 135 and 139.
	AZ Interstate 17 between mile markers 214 and 223.

This includes the following streams and drainages...
  Skunk Creek, Apache Wash, Cave Creek, New River, Deadman Wash and 
  North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3379 11220 3384 11216 3380 11202 3366 11206
      3364 11216 3371 11219

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

Iniguez

837 
WGUS75 KPSR 260004
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
504 PM MST Sun Jul 25 2021

AZC013-260045-
/O.CON.KPSR.FF.W.0077.000000T0000Z-210726T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
504 PM MST Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 545 PM MST THIS 
AFTERNOON FOR MARICOPA COUNTY...

At 504 PM MST, Earlier rain of 1 to 1.5 inches caused flash flooding 
of normally dry washes and low spots.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Radar and automated gauges.

IMPACT...Ongoing runoff will continue in normally dry washes.
         There will also be significant ponding of water in low
         spots.

Some locations that will experience flash flooding include...
  North Phoenix, North Glendale, New River, Cave Creek and Deer 
  Valley Airport.

This includes the following highways...
	AZ Route 74 between mile markers 28 and 30.
	AZ Route 303 between mile markers 135 and 139.
	

This includes the following streams and drainages...
  Skunk Creek, Apache Wash, Cave Creek, New River, Deadman Wash and 
  North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is ongoing. Hikers should avoid crossing through flooded 
washes.

&&

LAT...LON 3379 11220 3384 11216 3380 11202 3366 11206
      3364 11216 3371 11219

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

AJ

718 
WGUS75 KPSR 260046
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
546 PM MST Sun Jul 25 2021

AZC013-260056-
/O.EXP.KPSR.FF.W.0077.000000T0000Z-210726T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
546 PM MST Sun Jul 25 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR MARICOPA COUNTY...

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 1200 AM MST Monday for a 
portion of south central Arizona.

LAT...LON 3379 11220 3384 11216 3380 11202 3366 11206
      3364 11216 3371 11219

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 24, 10:57 PM MST	Areal Flood Advisory	PSR	Maricopa	5 hr
Jul 25, 4:45 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Jul 25, 6:27 AM MST	Areal Flood Advisory	PSR	Pinal	3 hr
Jul 25, 7:14 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Jul 25, 7:38 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Jul 25, 7:57 AM MST	Areal Flood Advisory	PSR	Pinal	3 hr
Jul 25, 8:01 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Jul 25, 8:45 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	4 hr
Jul 25, 8:51 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Jul 25, 9:00 AM MST	Flash Flood Warning Considerable damage threat	PSR	Pinal	4 hr
Jul 25, 9:39 AM MST	Areal Flood Advisory	PSR	Maricopa	17 min
Jul 25, 9:47 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Jul 25, 10:08 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	4 hr
Jul 25, 10:16 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 25, 10:41 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 25, 12:11 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Jul 25, 12:35 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 25, 12:54 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 25, 2:10 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	4 hr
Jul 25, 2:14 PM MST	Flash Flood Warning	PSR	Maricopa	3 hr
Jul 25, 2:18 PM MST	Flash Flood Warning	PSR	Maricopa	3 hr
Jul 25, 3:29 PM MST	Special Weather Statement	PSR	La Paz	31 min
Jul 25, 4:02 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr

Nearby

Flash Flood Warnings in Arizona, 2021 Every 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.