Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 233, NWS Phoenix, AZ

August 31, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 31, 2021, 12:50 AM MST for Maricopa County, Arizona. It was in force for 4 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: Aug 31, 2021, 12:50 AM MST (07:50 UTC)
Expired: Aug 31, 2021, 5:00 AM MST
In force: 4 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), 103 km from the middle of the area, began a volume at 07:49 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.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 00:00Z, 7.8 hours before the alert went out and 92 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: 238 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 3135 m above ground
0-6 km bulk shear: 1 kt
0-1 km storm-relative helicity: -12 m²/s²
0-3 km storm-relative helicity: 0 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

286 
WGUS55 KPSR 310750
FFWPSR
AZC013-311200-
/O.NEW.KPSR.FF.W.0233.210831T0750Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1250 AM MST Tue Aug 31 2021

The National Weather Service in Phoenix has issued a

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

* Until 500 AM MST.

* At 1250 AM MST, Doppler radar and automated rain gauges indicated 
  thunderstorms producing heavy rain across the warned area. Between 
  0.5 and 1.5 inches of rain have fallen. 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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 7.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	between mile markers 2 and 3.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, Quilotosa Wash, and Bender 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

6 follow-up statements

579 
WGUS75 KPSR 310822
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
122 AM MST Tue Aug 31 2021

AZC013-311200-
/O.CON.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
122 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 5 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 122 AM MST, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain across the warned area. Between 1 
and 2 inches of rain have fallen. 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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 8.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	near mile marker 2.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, and Bender 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

506 
WGUS75 KPSR 310855
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
155 AM MST Tue Aug 31 2021

AZC013-311200-
/O.CON.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
155 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 5 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 155 AM MST, Doppler radar and automated rain gauges indicated 
between 1 and 2 inches of rain have fallen in the warning area. 
Flash flooding is likely ongoing.

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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 8.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	near mile marker 2.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, Bender Wash, and Quilotosa 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

766 
WGUS75 KPSR 310947
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
247 AM MST Tue Aug 31 2021

AZC013-311200-
/O.CON.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
247 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 5 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 247 AM MST, Doppler radar and automated rain gauges indicated 
thunderstorms have produced Between 1 and 2 inches of rain in the 
warned area. Flash flooding is likely ongoing.

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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 8.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	near mile marker 2.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, Bender Wash and Quilotosa 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

686 
WGUS75 KPSR 311026
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
326 AM MST Tue Aug 31 2021

AZC013-311200-
/O.CON.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
326 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 5 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 326 AM MST, Doppler radar and automated rain gauges indicated 
thunderstorms produced between 1 and 2 inches of rain earlier. Flash 
flooding is likely ongoing.

HAZARD...Life threatening 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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 8.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	near mile marker 2.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, Bender Wash, and Quilotosa 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

331 
WGUS75 KPSR 311136
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
436 AM MST Tue Aug 31 2021

AZC013-311200-
/O.CON.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
436 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 5 AM MST EARLY THIS 
MORNING FOR MARICOPA COUNTY...

At 436 AM MST, Earlier rainfall of between 1 and 2 inches of rain 
has likely caused flash flooding is in the warned area.

HAZARD...Life threatening 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...
  Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 1 and 8.
	AZ Route 85 near mile marker 1...and
	between mile markers 119 and 124...and
	near mile marker 2.
	AZ Interstate 8 between mile markers 115 and 124.

This includes the following streams and drainages...
  Sand Tank Wash, Sauceda Wash, Bender Wash and Quilotosa 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 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

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

$$

AJ

361 
WGUS75 KPSR 311201
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
501 AM MST Tue Aug 31 2021

AZC013-311211-
/O.EXP.KPSR.FF.W.0233.000000T0000Z-210831T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
501 AM MST Tue Aug 31 2021

...FLASH FLOOD WARNING HAS EXPIRED 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.

LAT...LON 3258 11261 3268 11270 3281 11270 3290 11274
      3297 11275 3299 11275 3301 11273 3301 11271
      3297 11254 3293 11250 3282 11243 3277 11242
      3268 11244 3264 11247 3259 11255 3258 11259

$$

AJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 30, 8:18 PM MST	Special Weather Statement	PSR		27 min
Aug 30, 9:06 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	5 hr
Aug 30, 10:59 PM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	4 hr
Aug 30, 11:17 PM MST	Areal Flood Advisory	PSR	La Paz	3 hr
Aug 31, 12:06 AM MST	Special Weather Statement	PSR	Maricopa	39 min
Aug 31, 12:24 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 31, 2:55 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 31, 5:52 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 31, 12:39 PM MST	Special Weather Statement	PSR		66 min
Aug 31, 1:13 PM MST	Areal Flood Advisory	PSR	La Paz	6 hr
Aug 31, 1:24 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	13 hr
Aug 31, 1:35 PM MST	Special Weather Statement	PSR		70 min
Aug 31, 4:55 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	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.