Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 197, NWS Phoenix, AZ

August 16, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 16, 2021, 11:59 PM 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 16, 2021, 11:59 PM MST (06:59 UTC)
Expired: Aug 17, 2021, 5:40 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), 79 km from the middle of the area, began a volume at 07:01 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, 7.0 hours before the alert went out and 55 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: 2667 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 1942 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 44 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

643 
WGUS55 KPSR 170659
FFWPSR
AZC013-171100-
/O.NEW.KPSR.FF.W.0197.210817T0659Z-210817T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1159 PM MST Mon Aug 16 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  The Central burn scar in...
  Maricopa County in south central Arizona...

* Until 400 AM MST.

* At 1159 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Central Burn Scar. Between 0.5 and 1 inch of 
  rain has 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.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Central. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Central
           Burn Scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Central Burn Scar.

* Some locations that will experience flash flooding include...
  Phoenix, New River, Cave Creek and Anthem.

This includes the following highways...
	AZ Interstate 17 between mile markers 225 and 234.

This includes the following streams and drainages...
  Agua Fria River, Apache Wash, Skunk Creek, Cave Creek, Rodger 
  Creek, Little Squaw Creek, New River, Cottonwood Creek, Deadman 
  Wash and North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Central Burn Scar. Severe debris flows can also be 
anticipated across roads. Roads and driveways may be washed away in 
places. If you encounter flood waters...climb to safety.

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry arroyos is likely. The heavy rains 
will likely trigger rockslides, mudslides and debris flows in steep 
terrain, especially in and around these areas.

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

&&

LAT...LON 3402 11188 3392 11192 3389 11198 3384 11203
      3380 11207 3380 11213 3382 11218 3384 11219
      3390 11219 3395 11218 3400 11210 3404 11208
      3403 11202

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

$$

Hirsch

2 follow-up statements

141 
WGUS55 KPSR 171051
FFWPSR
AZC013-171300-
/O.EXT.KPSR.FF.W.0197.000000T0000Z-210817T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Phoenix has extended the

* Flash Flood Warning for...
  The Central burn scar in...
  Maricopa County in south central Arizona...

* Until 600 AM MST.

* At 351 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Central Burn Scar. Between 0.5 and 1.5 inches 
  of rain have fallen. Flash flooding is ongoing or expected to 
  begin shortly.

Excessive rainfall over the burn scar may result in debris flow 
moving through the Central Burn Scar. The debris flow can consist of 
rock, mud, vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Central
           Burn Scar.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Central Burn Scar.

* Some locations that will experience flash flooding include...
  Phoenix, New River, Cave Creek and Anthem.

This includes the following highways...
	AZ Interstate 17 between mile markers 225 and 234.

This includes the following streams and drainages...
  Agua Fria River, Apache Wash, Skunk Creek, Cave Creek, Rodger 
  Creek, Little Squaw Creek, New River, Cottonwood Creek, Deadman 
  Wash and North Canyon Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Central Burn Scar. Severe debris flows can also be 
anticipated across roads. Roads and driveways may be washed away in 
places. If you encounter flood waters...climb to safety.

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry arroyos is likely. The heavy rains 
will likely trigger rockslides, mudslides and debris flows in steep 
terrain, especially in and around these areas.

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

&&

LAT...LON 3402 11188 3392 11192 3389 11198 3384 11203
      3380 11207 3380 11213 3382 11218 3384 11219
      3390 11219 3395 11218 3400 11210 3404 11208
      3403 11202

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

$$

Hirsch

308 
WGUS75 KPSR 171240
FFSPSR

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

AZC013-171250-
/O.CAN.KPSR.FF.W.0197.000000T0000Z-210817T1300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
540 AM MST Tue Aug 17 2021

...FLASH FLOOD WARNING FOR THE CENTRAL BURN SCAR IS CANCELLED FOR 
MARICOPA COUNTY...

The heavy rain has ended and flooding is no longer expected to pose 
a threat. However, continue to avoid Skunk Creek, Cave Creek, 
Deadman Wash, and New River which likely have running water. Please 
continue to heed remaining road closures.

LAT...LON 3402 11188 3392 11192 3389 11198 3384 11203
      3380 11207 3380 11213 3382 11218 3384 11219
      3390 11219 3395 11218 3400 11210 3404 11208
      3403 11202

$$

Hirsch

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 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, 5:35 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	6 hr
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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.