Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 157, NWS Phoenix, AZ

August 12, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 12, 2021, 4:33 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 12, 2021, 4:33 AM MST (11:33 UTC)
Expired: Aug 12, 2021, 8:30 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), 45 km from the middle of the area, began a volume at 11:36 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, 11.6 hours before the alert went out and 57 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: 1157 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 1687 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -3 m²/s²
0-3 km storm-relative helicity: 52 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

375 
WGUS55 KPSR 121133
FFWPSR
AZC013-121530-
/O.NEW.KPSR.FF.W.0157.210812T1133Z-210812T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  The Bush Fire Burn Scar in...
  Maricopa County in south central Arizona...

* Until 830 AM MST.

* At 433 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Bush Fire Burn Scar. Between 1 and 1.5 inches 
  of rain have fallen. Additional rainfall amounts up to 1 inch are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Salt River. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Bush Fire
           Burn Scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Bush Fire Burn Scar.

* Some locations that will experience flash flooding include...
  Four Peaks, Saguaro Lake and Salt River Tubing Recreation Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3372 11134 3369 11133 3362 11126 3360 11122
      3358 11125 3358 11128 3359 11131 3359 11134
      3358 11136 3357 11135 3355 11144 3356 11149
      3355 11159 3358 11160 3362 11157 3367 11156
      3369 11153 3367 11150 3369 11144 3375 11138

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

$$

CK

3 follow-up statements

988 
WGUS75 KPSR 121208
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
508 AM MST Thu Aug 12 2021

AZC013-121530-
/O.CON.KPSR.FF.W.0157.000000T0000Z-210812T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
508 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING FOR THE BUSH FIRE BURN SCAR REMAINS IN EFFECT 
UNTIL 830 AM MST THIS MORNING FOR MARICOPA COUNTY...

At 508 AM MST, Doppler radar indicated thunderstorms producing heavy 
rain over the Bush Fire Burn Scar. 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 ongoing or expected 
to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Salt River. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Bush Fire Burn Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Bush Fire Burn Scar.

Some locations that will experience flash flooding include...
  Four Peaks, Saguaro Lake and Salt River Tubing Recreation Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3372 11134 3369 11133 3362 11126 3360 11122
      3358 11125 3358 11128 3359 11131 3359 11134
      3358 11136 3357 11135 3355 11144 3356 11149
      3355 11159 3358 11160 3362 11157 3367 11156
      3369 11153 3367 11150 3369 11144 3375 11138

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

$$

CK

445 
WGUS75 KPSR 121459
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
759 AM MST Thu Aug 12 2021

AZC013-121530-
/O.CON.KPSR.FF.W.0157.000000T0000Z-210812T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
759 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING FOR THE BUSH FIRE BURN SCAR REMAINS IN EFFECT 
UNTIL 830 AM MST THIS MORNING FOR MARICOPA COUNTY...

At 759 AM MST, Doppler radar indicated thunderstorms producing heavy 
rain over the Bush Fire Burn Scar. Between 1.5 and 2.5 inches of 
rain have fallen. Flash flooding is ongoing or expected to begin 
shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Salt River. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Bush Fire Burn Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Bush Fire Burn Scar.

Some locations that will experience flash flooding include...
  Four Peaks, Saguaro Lake and Salt River Tubing Recreation Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3372 11134 3369 11133 3362 11126 3360 11122
      3358 11125 3358 11128 3359 11131 3359 11134
      3358 11136 3357 11135 3355 11144 3356 11149
      3355 11159 3358 11160 3362 11157 3367 11156
      3369 11153 3367 11150 3369 11144 3375 11138

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

$$

INS

999 
WGUS75 KPSR 121521
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
821 AM MST Thu Aug 12 2021

AZC013-121531-
/O.EXP.KPSR.FF.W.0157.000000T0000Z-210812T1530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
821 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING FOR THE BUSH FIRE BURN SCAR WILL EXPIRE AT 
830 AM MST THIS MORNING FOR MARICOPA COUNTY...

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

LAT...LON 3372 11134 3369 11133 3362 11126 3360 11122
      3358 11125 3358 11128 3359 11131 3359 11134
      3358 11136 3357 11135 3355 11144 3356 11149
      3355 11159 3358 11160 3362 11157 3367 11156
      3369 11153 3367 11150 3369 11144 3375 11138

$$

INS

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, 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, 3:11 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	5 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.