Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 243, NWS Phoenix, AZ

September 1, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Sep 1, 2021, 10:09 PM MST for Maricopa County, Arizona. It was in force for 5 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 1, 2021, 10:09 PM MST (05:09 UTC)
Expired: Sep 2, 2021, 3:23 AM MST
In force: 5 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), 109 km from the middle of the area, began a volume at 05:11 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.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 5.2 hours before the alert went out and 79 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: 518 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 1794 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

881 
WGUS55 KPSR 020509
FFWPSR
AZC013-021315-
/O.NEW.KPSR.FF.W.0243.210902T0509Z-210902T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1009 PM MST Wed Sep 1 2021

The National Weather Service in Phoenix has issued a

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

* Until 615 AM MST Thursday.

* At 1009 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 1.5 inches of rain have 
  fallen. Additional rainfall amounts of 0.5 to 1 inch 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.

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

* Some locations that will experience flash flooding include...
  Buckeye, Tonopah, Wintersburg, Palo Verde Nuclear Generation 
  Station, Palo Verde, Hassayampa and Arlington.

This includes the following highways...
	AZ Interstate 10 between mile markers 100 and 109.
	AZ Route 85 between mile markers 148 and 154.

This includes the following streams and drainages...
  Wagner Wash, Dickey Wash, Star Wash, Delaney Wash, Winters Wash, 
  Gila River, Fourmile Wash, Coyote Wash, Centennial Wash, Old Camp 
  Wash, Beer Bottle Wash, Hassayampa River, Daggs Wash and 
  Jackrabbit Wash.

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 3328 11287 3333 11300 3342 11308 3351 11309
      3357 11305 3363 11298 3365 11281 3363 11268
      3360 11262 3355 11257 3341 11256 3332 11263
      3331 11270

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

$$

Hirsch

3 follow-up statements

229 
WGUS75 KPSR 020627
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1127 PM MST Wed Sep 1 2021

AZC013-021315-
/O.CON.KPSR.FF.W.0243.000000T0000Z-210902T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1127 PM MST Wed Sep 1 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 AM MST THURSDAY 
FOR MARICOPA COUNTY...

At 1127 PM MST, Doppler radar indicated that 1 to 1.5 inches of rain 
have fallen. Flash flooding is likely ongoing.

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

SOURCE...Radar.

IMPACT...Life threatening flash flooding of normally dry washes,
         urban areas, highways, streets and underpasses.

This includes the following highways...
	AZ Interstate 10 between mile markers 100 and 109.
	AZ Route 85 between mile markers 148 and 154.

This includes the following streams and drainages...
  Wagner Wash, Dickey Wash, Star Wash, Delaney Wash, Winters Wash,  
  Fourmile Wash, Coyote Wash, Centennial Wash, Old Camp Wash, Beer 
  Bottle Wash, Hassayampa River, Daggs Wash and Jackrabbit Wash.

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 3328 11287 3333 11300 3342 11308 3351 11309
      3357 11305 3363 11298 3365 11281 3363 11268
      3360 11262 3355 11257 3341 11256 3332 11263
      3331 11270

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

$$

AJ

482 
WGUS75 KPSR 020821
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
121 AM MST Thu Sep 2 2021

AZC013-021315-
/O.CON.KPSR.FF.W.0243.000000T0000Z-210902T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
121 AM MST Thu Sep 2 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 AM MST THIS 
MORNING FOR MARICOPA COUNTY...

At 121 AM MST, Earlier, between 0.5 and 1.5 inches of rain fell in 
the warned area. Flash flooding is likely ongoing.

HAZARD...Life threatening flash flooding.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of normally dry washes,
         rural roads, and low-lying areas.

Some locations that will experience flash flooding include...
  Buckeye, Tonopah, Wintersburg, and Arlington.

This includes the following highways...
	AZ Interstate 10 between mile markers 100 and 109.
	AZ Route 85 between mile markers 148 and 154.

This includes the following streams and drainages...
  Wagner Wash, Dickey Wash, Star Wash, Delaney Wash, Winters Wash, 
  Fourmile Wash, Coyote Wash, Centennial Wash, Old Camp Wash, Beer 
  Bottle Wash, Hassayampa River, Daggs Wash and Jackrabbit Wash.

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 3328 11287 3333 11300 3342 11308 3351 11309
      3357 11305 3363 11298 3365 11281 3363 11268
      3360 11262 3355 11257 3341 11256 3332 11263
      3331 11270

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

$$

AJ

432 
WGUS75 KPSR 021023
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
323 AM MST Thu Sep 2 2021

AZC013-021033-
/O.CAN.KPSR.FF.W.0243.000000T0000Z-210902T1315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
323 AM MST Thu Sep 2 2021

...FLASH FLOOD WARNING IS CANCELLED 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 3328 11287 3333 11300 3342 11308 3351 11309
      3357 11305 3363 11298 3365 11281 3363 11268
      3360 11262 3355 11257 3341 11256 3332 11263
      3331 11270

$$

AJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 1, 5:17 PM MST	Special Weather Statement	PSR		58 min
Sep 1, 5:45 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Sep 1, 7:18 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	88 min
Sep 1, 9:35 PM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	6 hr
Sep 1, 11:09 PM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	7 hr
Sep 2, 12:41 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Sep 2, 1:52 AM MST	Areal Flood Advisory	PSR	Pinal	3 hr
Sep 2, 5:22 AM MST	Areal Flood Advisory	PSR	Pinal	4 hr
Sep 2, 6:11 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Sep 2, 3:25 PM MST	Special Weather Statement	PSR	Maricopa	65 min
Sep 2, 3:51 PM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.