Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 50, NWS Phoenix, AZ

July 21, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 21, 2021, 3:51 PM 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: Jul 21, 2021, 3:51 PM MST (22:51 UTC)
Expired: Jul 21, 2021, 8:15 PM 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), 152 km from the middle of the area, began a volume at 22:53 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, 10.9 hours before the alert went out and 120 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: 5 J/kg
Mixed-layer CIN: -244 J/kg
Mixed-layer LCL: 2438 m above ground
0-6 km bulk shear: 2 kt
0-1 km storm-relative helicity: -11 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

583 
WGUS55 KPSR 212251
FFWPSR
AZC013-220315-
/O.NEW.KPSR.FF.W.0050.210721T2251Z-210722T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
351 PM MST Wed Jul 21 2021

The National Weather Service in Phoenix has issued a

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

* Until 815 PM MST.

* At 351 PM 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. 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 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...
  Aguila.

This includes the following highways...
	US Highway 60 between mile markers 80 and 89.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3389 11295 3389 11309 3390 11318 3393 11329
      3400 11330 3400 11325 3400 11309 3400 11294

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

$$

MS

2 follow-up statements

103 
WGUS75 KPSR 220229
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
729 PM MST Wed Jul 21 2021

AZC013-220315-
/O.CON.KPSR.FF.W.0050.000000T0000Z-210722T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
729 PM MST Wed Jul 21 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM MST THIS 
EVENING FOR MARICOPA COUNTY...

At 729 PM 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...
  Aguila.

This includes the following highways...
	US Highway 60 between mile markers 80 and 89.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3389 11295 3389 11309 3390 11318 3393 11329
      3400 11330 3400 11325 3400 11309 3400 11294

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

$$

Iniguez

331 
WGUS75 KPSR 220317
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
817 PM MST Wed Jul 21 2021

AZC013-220327-
/O.EXP.KPSR.FF.W.0050.000000T0000Z-210722T0315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
817 PM MST Wed Jul 21 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR THE AGUILA AREA IN 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 3389 11295 3389 11309 3390 11318 3393 11329
      3400 11330 3400 11325 3400 11309 3400 11294

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 5:15 PM MST	Special Weather Statement	PSR	La Paz	45 min
Jul 20, 5:21 PM MST	Special Weather Statement	PSR	Gila	39 min
Jul 20, 5:32 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Jul 20, 6:22 PM MST	Special Weather Statement	PSR		38 min
Jul 20, 7:22 PM MST	Special Weather Statement	PSR	Pinal	53 min
Jul 20, 8:19 PM MST	Special Weather Statement	PSR	Pinal	41 min
Jul 20, 8:56 PM MST	Special Weather Statement	PSR	Pinal	49 min
Jul 20, 11:51 PM MST	Special Weather Statement	PSR		39 min
Jul 21, 2:21 AM MST	Flash Flood Watch	PSR	Gila, Maricopa, Pinal	5 days
Jul 21, 8:12 AM MST	Blowing Dust Advisory	PSR	La Paz, Maricopa, Yuma	12 hr
Jul 21, 2:45 PM MST	Special Weather Statement	PSR		45 min
Jul 21, 2:46 PM MST	Dust Storm Warning	PSR	Pinal	40 min
Jul 21, 3:07 PM MST	Special Weather Statement	PSR		38 min
Jul 21, 3:34 PM MST	Special Weather Statement	PSR	Maricopa	41 min
Jul 21, 3:37 PM MST	Special Weather Statement	PSR	La Paz	38 min
Jul 21, 3:42 PM MST	Special Weather Statement	PSR	Yuma	48 min
Jul 21, 3:45 PM MST	Special Weather Statement	PSR	Maricopa	45 min
Jul 21, 3:46 PM MST	Special Weather Statement	PSR		29 min
Jul 21, 3:53 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	37 min
Jul 21, 3:55 PM MST	Special Weather Statement	PSR	Maricopa	50 min
Jul 21, 4:01 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	29 min
Jul 21, 4:11 PM MST	Special Weather Statement	PSR	La Paz	49 min
Jul 21, 4:26 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 21, 4:28 PM MST	Special Weather Statement	PSR	Maricopa	47 min
Jul 21, 4:32 PM MST	Special Weather Statement	PSR		28 min
Jul 21, 4:55 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Jul 21, 4:59 PM MST	Special Weather Statement	PSR		46 min

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.