Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 200, NWS Phoenix, AZ

August 17, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 17, 2021, 5:35 AM MST for Maricopa County, Arizona. It was in force for 6 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 17, 2021, 5:35 AM MST (12:35 UTC)
Expired: Aug 17, 2021, 11:18 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), 74 km from the middle of the area, began a volume at 12:37 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.

What was reported inside it

Time	Report	Where	Remark
Aug 17, 8:00 AM MST	FLASH FLOOD	2 W Goodyear, AZ	DELAYED REPORT CITY OF GOODYEAR REPORTED CITRUS RD CLOSED BETWEEN I-10 AND VAN BUREN, AND BETWEEN YUMA AND DURANGO DUE TO FLOODING.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Phoenix, AZ (KPSR), launched 12:00Z, 0.6 hours before the alert went out and 46 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: 14 J/kg
Mixed-layer CIN: -428 J/kg
Mixed-layer LCL: 1452 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: -1 m²/s²
0-3 km storm-relative helicity: 154 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

As transmitted.

966 
WGUS55 KPSR 171235
FFWPSR
AZC013-171830-
/O.NEW.KPSR.FF.W.0200.210817T1235Z-210817T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
535 AM MST Tue Aug 17 2021

The National Weather Service in Phoenix has issued a

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

* Until 1130 AM MST.

* At 535 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 1 inch of rain has 
  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...
  Phoenix, Glendale, Surprise, Avondale, Goodyear, Buckeye, El 
  Mirage, Youngtown, Cashion, Sun City, Litchfield Park, Liberty, 
  Estrella Mountain Ranch, Perryville, Estrella Mountain Park, 
  Phoenix International Raceway and Luke AFB.

This includes the following highways...
	AZ Interstate 10 between mile markers 117 and 126.
	AZ Route 303 between mile markers 105 and 110.
	AZ Route 85 between mile markers 134 and 143.

This includes the following streams and drainages...
  Agua Fria River, Lum Wash, Waterman Wash, Beardsley Canal, Gila 
  River, Enterprise Canal, Corgett Wash and Rainbow Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3358 11236 3359 11233 3356 11230 3348 11230
      3340 11230 3335 11232 3328 11239 3318 11242
      3313 11251 3312 11274 3321 11275 3329 11270
      3338 11259 3346 11255 3355 11243

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

$$

Hirsch

1 follow-up statement

813 
WGUS75 KPSR 171818
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1118 AM MST Tue Aug 17 2021

AZC013-171828-
/O.CAN.KPSR.FF.W.0200.000000T0000Z-210817T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1118 AM MST Tue Aug 17 2021

...FLASH FLOOD WARNING IS CANCELLED 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 3358 11236 3359 11233 3356 11230 3348 11230
      3340 11230 3335 11232 3328 11239 3318 11242
      3313 11251 3312 11274 3321 11275 3329 11270
      3338 11259 3346 11255 3355 11243

$$

MS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 16, 5:15 PM MST	Special Weather Statement	PSR	Gila	45 min
Aug 16, 5:46 PM MST	Special Weather Statement	PSR		44 min
Aug 16, 6:07 PM MST	Special Weather Statement	PSR	Gila	38 min
Aug 16, 6:14 PM MST	Severe Thunderstorm Warning	PSR	Gila	46 min
Aug 16, 6:37 PM MST	Special Weather Statement	PSR	Pinal	53 min
Aug 16, 6:55 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	6 hr
Aug 16, 8:24 PM MST	Special Weather Statement	PSR		51 min
Aug 16, 8:41 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	5 hr
Aug 16, 8:53 PM MST	Special Weather Statement	PSR	Gila	52 min
Aug 16, 9:08 PM MST	Special Weather Statement	PSR	Gila	52 min
Aug 16, 9:22 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa, Pinal	38 min
Aug 16, 9:41 PM MST	Severe Thunderstorm Warning	PSR	Gila, Maricopa, Pinal	49 min
Aug 16, 9:49 PM MST	Severe Thunderstorm Warning Considerable damage threat	PSR	Gila, Maricopa	41 min
Aug 16, 10:01 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Aug 16, 10:01 PM MST	Special Weather Statement	PSR		44 min
Aug 16, 10:05 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Aug 16, 10:14 PM MST	Severe Thunderstorm Warning Considerable damage threat	PSR	Gila, Maricopa, Pinal	46 min
Aug 16, 10:22 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	10 hr
Aug 16, 10:28 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa, Pinal	10 hr
Aug 16, 10:36 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	10 hr
Aug 16, 10:38 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal	67 min
Aug 16, 10:48 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	9 hr
Aug 16, 10:54 PM MST	Severe Thunderstorm Warning Destructive damage threat	PSR	Maricopa, Pinal	51 min
Aug 16, 10:58 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	7 hr
Aug 16, 11:04 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	56 min
Aug 16, 11:07 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	7 hr
Aug 16, 11:16 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	7 hr
Aug 16, 11:26 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	8 hr
Aug 16, 11:31 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	44 min
Aug 16, 11:41 PM MST	Severe Thunderstorm Warning Considerable damage threat	PSR	Maricopa, Pinal	49 min
Aug 16, 11:47 PM MST	Dust Storm Warning	PSR	Maricopa	58 min
Aug 16, 11:50 PM MST	Special Weather Statement	PSR		40 min
Aug 16, 11:52 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	38 min
Aug 16, 11:56 PM MST	Flash Flood Warning Considerable damage threat	PSR	Pinal	7 hr
Aug 16, 11:59 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Aug 17, 12:01 AM MST	Dust Storm Warning	PSR	Maricopa, Pinal	59 min
Aug 17, 12:09 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	8 hr
Aug 17, 12:32 AM MST	Special Weather Statement	PSR		43 min
Aug 17, 12:36 AM MST	Special Weather Statement	PSR	Maricopa	24 min
Aug 17, 4:05 AM MST	Areal Flood Advisory	PSR	Maricopa	4 hr
Aug 17, 4:26 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Aug 17, 5:29 AM MST	Special Weather Statement	PSR	Maricopa	76 min
Aug 17, 6:26 AM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Pinal	5 hr
Aug 17, 8:42 AM MST	Areal Flood Warning	PSR	Gila	5 days
Aug 17, 4:46 PM MST	Special Weather Statement	PSR		44 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.