Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 162, NWS Phoenix, AZ

August 12, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 12, 2021, 3:11 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: Aug 12, 2021, 3:11 PM MST (22:11 UTC)
Expired: Aug 12, 2021, 8:06 PM 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), 82 km from the middle of the area, began a volume at 22:15 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 12:00Z, 10.2 hours before the alert went out and 67 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: 1266 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 865 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 99 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

709 
WGUS55 KPSR 122211
FFWPSR
AZC013-130215-
/O.NEW.KPSR.FF.W.0162.210812T2211Z-210813T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
311 PM MST Thu Aug 12 2021

The National Weather Service in Phoenix has issued a

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

* Until 715 PM MST.

* At 311 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has fallen. 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 normally dry
           washes, highways and low spots.

* Some locations that will experience flash flooding include...
  Open desert near and east of Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 10 and 19.
	AZ Interstate 8 between mile markers 124 and 133.

This includes the following streams and drainages...
  Waterman Wash, Sauceda Wash and Bender Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3303 11258 3315 11246 3307 11228 3284 11234
      3288 11261

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

$$

AJ

4 follow-up statements

579 
WGUS75 KPSR 122305
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
405 PM MST Thu Aug 12 2021

AZC013-130215-
/O.CON.KPSR.FF.W.0162.000000T0000Z-210813T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
405 PM MST Thu Aug 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 715 PM MST THIS 
EVENING FOR MARICOPA COUNTY...

At 405 PM MST, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.5 and 1 inch of rain has 
fallen. 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 normally dry washes,
         highways and low spots.

Some locations that will experience flash flooding include...
  Open desert near and east of Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 10 and 19.
	AZ Interstate 8 between mile markers 124 and 133.

This includes the following streams and drainages...
  Waterman Wash, Sauceda Wash and Bender Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3303 11258 3315 11246 3307 11228 3284 11234
      3288 11261

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

$$

AJ

622 
WGUS75 KPSR 130027
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
527 PM MST Thu Aug 12 2021

AZC013-130215-
/O.CON.KPSR.FF.W.0162.000000T0000Z-210813T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
527 PM MST Thu Aug 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 715 PM MST THIS 
EVENING FOR MARICOPA COUNTY...

At 527 PM MST, Highway Patrol reported flooding of Highway 238 east 
of Gila Bend requiring closure of the roadway.

HAZARD...Life threatening flash flooding.

SOURCE...Law enforcement reported.

IMPACT...Life threatening flash flooding of normally dry washes,
         highways and low lying areas.

Some locations that will experience flash flooding include...
  Open desert near and east of Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 10 and 19.
	AZ Interstate 8 between mile markers 124 and 133.

This includes the following streams and drainages...
  Waterman Wash, Sauceda Wash, Bender Wash, and Sand Tank Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3303 11258 3315 11246 3307 11228 3284 11234
      3288 11261

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

AJ

580 
WGUS55 KPSR 130211
FFWPSR
AZC013-130315-
/O.EXT.KPSR.FF.W.0162.000000T0000Z-210813T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
711 PM MST Thu Aug 12 2021

The National Weather Service in Phoenix has extended the

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

* Until 815 PM MST.

* At 711 PM MST, Highway Patrol reported Highway 238 had flooding. 
  Between 0.5 and 1 inch of rain had fallen in the area earlier in 
  the afternoon.

  HAZARD...Flooding of Highway

  SOURCE...Law enforcement reported.

  IMPACT...Life threatening flash flooding of highways, normally
           dry washes and low lying areas.

* Some locations that will experience flash flooding include...
  Open desert near and east of Gila Bend.

This includes the following highways...
	AZ Route 238 between mile markers 10 and 19.
	AZ Interstate 8 between mile markers 124 and 133.

This includes the following streams and drainages...
  Sand Tank Wash, Waterman Wash, Sauceda Wash and Bender Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3303 11258 3315 11246 3307 11228 3284 11234
      3288 11261

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

AJ

206 
WGUS75 KPSR 130306
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
806 PM MST Thu Aug 12 2021

AZC013-130316-
/O.CAN.KPSR.FF.W.0162.000000T0000Z-210813T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
806 PM MST Thu Aug 12 2021

...FLASH FLOOD WARNING IS CANCELLED FOR MARICOPA COUNTY...

Flood waters have receded. The heavy rain has ended and water has 
likely receded. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 500 PM MST Sunday for a 
portion of south central Arizona.

LAT...LON 3303 11258 3315 11246 3307 11228 3284 11234
      3288 11261

$$

AJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 5:03 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	42 min
Aug 11, 5:14 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 11, 5:14 PM MST	Special Weather Statement	PSR	Maricopa	46 min
Aug 11, 5:30 PM MST	Flash Flood Warning	PSR	Maricopa	2 hr
Aug 11, 5:30 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	45 min
Aug 11, 5:39 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 11, 5:49 PM MST	Special Weather Statement	PSR		41 min
Aug 11, 5:57 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Aug 11, 6:07 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	53 min
Aug 11, 6:12 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	48 min
Aug 11, 6:19 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	41 min
Aug 11, 6:20 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Aug 11, 6:40 PM MST	Flash Flood Warning	PSR	Maricopa	4 hr
Aug 11, 7:02 PM MST	Special Weather Statement	PSR		58 min
Aug 11, 7:11 PM MST	Special Weather Statement	PSR		64 min
Aug 11, 7:26 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	3 hr
Aug 11, 7:53 PM MST	Special Weather Statement	PSR	La Paz	37 min
Aug 12, 2:00 AM MST	Special Weather Statement	PSR		45 min
Aug 12, 2:42 AM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	4 hr
Aug 12, 2:45 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 12, 3:34 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 12, 4:16 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Aug 12, 4:33 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Aug 12, 5:17 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Aug 12, 6:04 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Aug 12, 6:21 AM MST	Areal Flood Advisory	PSR	Maricopa	46 min
Aug 12, 7:00 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Aug 12, 10:09 AM MST	Areal Flood Warning	PSR	Gila	8 hr
Aug 12, 10:46 AM MST	Areal Flood Warning	PSR	Maricopa	15 hr
Aug 12, 1:30 PM MST	Flash Flood Watch	PSR	Gila, Maricopa, Pinal	5 days
Aug 12, 2:11 PM MST	Special Weather Statement	PSR	La Paz	34 min
Aug 12, 2:30 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 12, 2:45 PM MST	Areal Flood Advisory	PSR	La Paz	3 hr
Aug 12, 2:54 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Maricopa	4 hr
Aug 12, 3:34 PM MST	Special Weather Statement	PSR		41 min
Aug 12, 4:14 PM MST	Areal Flood Advisory	PSR	Maricopa, Yuma	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.