Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 134, NWS Phoenix, AZ

August 10, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 10, 2021, 8:06 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 10, 2021, 8:06 AM MST (15:06 UTC)
Expired: Aug 10, 2021, 12:15 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), 85 km from the middle of the area, began a volume at 15:08 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, 3.1 hours before the alert went out and 76 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: 110 J/kg
Mixed-layer CIN: -193 J/kg
Mixed-layer LCL: 1490 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 93 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

181 
WGUS55 KPSR 101506
FFWPSR
AZC013-101915-
/O.NEW.KPSR.FF.W.0134.210810T1506Z-210810T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
806 AM MST Tue Aug 10 2021

The National Weather Service in Phoenix has issued a

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

* Until 1215 PM MST.

* At 806 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 of 0.5 to 1.5 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...
  Big Horn and Freeman.

This includes the following highways...
	AZ Interstate 8 between mile markers 127 and 136.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3292 11249 3294 11235 3288 11229 3284 11229
      3280 11236 3280 11252 3282 11261 3293 11254

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

$$

SDB

2 follow-up statements

776 
WGUS75 KPSR 101704
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1004 AM MST Tue Aug 10 2021

AZC013-101915-
/O.CON.KPSR.FF.W.0134.000000T0000Z-210810T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1004 AM MST Tue Aug 10 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1215 PM MST THIS 
AFTERNOON FOR MARICOPA COUNTY...

At 1004 AM MST, Doppler radar indicated heavy rain across the warned 
area. Between 1.5 and 2.5 inches of rain have fallen. Flash flooding 
is ongoing or expected to begin shortly.

HAZARD...Life threatening flash flooding. Heavy rain 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...
  Big Horn and Freeman.

This includes the following highways...
	AZ Interstate 8 between mile markers 127 and 136.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3292 11249 3294 11235 3288 11229 3284 11229
      3280 11236 3280 11252 3282 11261 3293 11254

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

$$

SDB

224 
WGUS75 KPSR 101911
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1211 PM MST Tue Aug 10 2021

AZC013-101921-
/O.EXP.KPSR.FF.W.0134.000000T0000Z-210810T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1211 PM MST Tue Aug 10 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1215 PM MST THIS AFTERNOON 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 3292 11249 3294 11235 3288 11229 3284 11229
      3280 11236 3280 11252 3282 11261 3293 11254

$$

SDB

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 5:24 PM MST	Areal Flood Advisory	PSR	La Paz	3 hr
Aug 9, 5:44 PM MST	Special Weather Statement	PSR	La Paz	46 min
Aug 9, 6:22 PM MST	Special Weather Statement	PSR		38 min
Aug 9, 10:11 PM MST	Special Weather Statement	PSR	Gila	34 min
Aug 9, 10:40 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Aug 9, 11:51 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	8 hr
Aug 10, 1:40 AM MST	Special Weather Statement	PSR	Maricopa	50 min
Aug 10, 1:54 AM MST	Special Weather Statement	PSR	Maricopa	51 min
Aug 10, 2:15 AM MST	Special Weather Statement	PSR	Maricopa	45 min
Aug 10, 2:23 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	2 hr
Aug 10, 4:27 AM MST	Special Weather Statement	PSR	La Paz	48 min
Aug 10, 5:07 AM MST	Special Weather Statement	PSR	La Paz	53 min
Aug 10, 5:09 AM MST	Areal Flood Advisory	PSR	La Paz	2 hr
Aug 10, 5:52 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	5 hr
Aug 10, 6:21 AM MST	Special Weather Statement	PSR	La Paz	39 min
Aug 10, 7:39 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Aug 10, 8:00 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 10, 8:30 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	7 hr
Aug 10, 9:54 AM MST	Areal Flood Advisory	PSR	La Paz	3 hr
Aug 10, 3:05 PM MST	Areal Flood Warning	PSR	Maricopa, Pinal	7 hr
Aug 10, 4:43 PM MST	Special Weather Statement	PSR		62 min
Aug 10, 4:44 PM MST	Special Weather Statement	PSR		61 min
Aug 10, 4:56 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	49 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.