Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 158, NWS Phoenix, AZ

August 12, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 12, 2021, 5:17 AM MST for Maricopa County, Arizona. It was in force for 6 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, 5:17 AM MST (12:17 UTC)
Expired: Aug 12, 2021, 11:15 AM MST
In force: 6 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), 47 km from the middle of the area, began a volume at 12:17 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, 0.3 hours before the alert went out and 41 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.

134 
WGUS55 KPSR 121217
FFWPSR
AZC013-121615-
/O.NEW.KPSR.FF.W.0158.210812T1217Z-210812T1615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
517 AM 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 915 AM MST.

* At 517 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 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.

  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...
  Scottsdale, Fountain Hills, Rio Verde, McDowell Mountain Park and 
  Fort McDowell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3379 11175 3378 11165 3374 11156 3370 11154
      3365 11158 3360 11162 3362 11175 3368 11181
      3374 11182 3378 11179

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

$$

CK

2 follow-up statements

622 
WGUS75 KPSR 121313
FFSPSR

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

AZC013-121615-
/O.CON.KPSR.FF.W.0158.000000T0000Z-210812T1615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
613 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 AM MST THIS 
MORNING FOR MARICOPA COUNTY...

At 613 AM MST, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. 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.

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...
  Scottsdale, Fountain Hills, Rio Verde, McDowell Mountain Park and 
  Fort McDowell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3379 11175 3378 11165 3374 11156 3370 11154
      3365 11158 3360 11162 3362 11175 3368 11181
      3374 11182 3378 11179

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

$$

CK

097 
WGUS55 KPSR 121602
FFWPSR
AZC013-121815-
/O.EXT.KPSR.FF.W.0158.000000T0000Z-210812T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
902 AM 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 1115 AM MST.

* At 902 AM MST, Doppler radar indicated thunderstorms had produced 
  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.

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

* Some locations that will experience flash flooding include...
  Scottsdale, Fountain Hills, Rio Verde, McDowell Mountain Park and 
  Fort McDowell.

Additional locations that will experience flooding include...
Areas along Sycamore Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3379 11175 3378 11165 3374 11156 3370 11154
      3365 11158 3360 11162 3362 11175 3368 11181
      3374 11182 3378 11179

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

$$

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, 4:33 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 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.