Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 44, NWS Phoenix, AZ

July 16, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 16, 2021, 8:55 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 16, 2021, 8:55 PM MST (03:55 UTC)
Expired: Jul 17, 2021, 1:00 AM MST
In force: 4 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Flood severity: None

County Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 76 km from the middle of the area, began a volume at 03:54 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, 3.9 hours before the alert went out and 45 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: 1249 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 2188 m above ground
0-6 km bulk shear: 11 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 147 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

699 
WGUS55 KPSR 170355
FFWPSR
AZC013-170800-
/O.NEW.KPSR.FF.W.0044.210717T0355Z-210717T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
855 PM MST Fri Jul 16 2021

The National Weather Service in Phoenix has issued a

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

* Until 100 AM MST.

* At 855 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1.5 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Glendale, Surprise, Avondale, Goodyear, Buckeye and Litchfield 
  Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3363 11245 3359 11237 3353 11239 3345 11235
      3342 11244 3345 11252 3361 11253

FLASH FLOOD...RADAR INDICATED

$$

18

2 follow-up statements

988 
WGUS75 KPSR 170449
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
949 PM MST Fri Jul 16 2021

AZC013-170800-
/O.CON.KPSR.FF.W.0044.000000T0000Z-210717T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
949 PM MST Fri Jul 16 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1 AM MST SATURDAY FOR 
MARICOPA COUNTY...

At 949 PM MST, Doppler radar indicated thunderstorms have produced 
heavy rain across the warned area. Between 0.5 and 1.5 inches of 
rain have fallen. Flash flooding is ongoing or expected to begin 
shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Glendale, Surprise, Avondale, Goodyear, Buckeye and Litchfield 
  Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 3363 11245 3359 11237 3353 11239 3345 11235
      3342 11244 3345 11252 3361 11253

FLASH FLOOD...RADAR INDICATED

$$

18

903 
WGUS75 KPSR 170755
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1255 AM MST Sat Jul 17 2021

AZC013-170805-
/O.EXP.KPSR.FF.W.0044.000000T0000Z-210717T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
1255 AM MST Sat Jul 17 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1 AM MST EARLY THIS MORNING 
FOR MARICOPA COUNTY...

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

LAT...LON 3363 11245 3359 11237 3353 11239 3345 11235
      3342 11244 3345 11252 3361 11253

$$

CK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 16, 5:57 PM MST	Special Weather Statement	PSR		48 min
Jul 16, 6:10 PM MST	Dust Storm Advisory	PSR	Pinal	50 min
Jul 16, 6:36 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal	39 min
Jul 16, 6:57 PM MST	Dust Storm Warning	PSR	Maricopa, Pinal	33 min
Jul 16, 7:17 PM MST	Special Weather Statement	PSR		28 min
Jul 16, 7:31 PM MST	Dust Storm Advisory	PSR	Maricopa	44 min
Jul 16, 7:57 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
Jul 16, 8:23 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	4 hr
Jul 16, 8:38 PM MST	Special Weather Statement	PSR	Maricopa	37 min
Jul 16, 8:43 PM MST	Special Weather Statement	PSR		32 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.