Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 156, NWS Phoenix, AZ

August 12, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 12, 2021, 4:16 AM MST for Maricopa County, Arizona. It was in force for 4 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 12, 2021, 4:16 AM MST (11:16 UTC)
Expired
Aug 12, 2021, 8:15 AM 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), 66 km from the middle of the area, began a volume at 11:20 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

TimeReportWhereRemark
Aug 12, 6:00 AM MSTFLASH FLOOD8 Ene Carefree, AZ***DELAYED REPORT*** SOCIAL MEDIA VIDEO SHOWS BARTLETT DAM RD AT TYPICALLY DRY CAMP CREEK LOW WATER CROSSING WAS IMPASSABLE DUE TO 6-8 INCHES OF FLOWING WATER OVER THE ROAD. ADDITIONALLY, HORSESHOE DAM RD BETWEEN BARTLETT DAM RD AND HORSESHOE LAKE WAS CLOSED B

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 00:00Z, 11.3 hours before the alert went out and 56 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-pSkew-T log-p diagram, Phoenix, AZ at 00:00Z on 2021-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1157 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Phoenix, AZ at 00:00Z on 2021-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -3 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1157 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
1687 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-3 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

014 
WGUS55 KPSR 121116
FFWPSR
AZC013-121515-
/O.NEW.KPSR.FF.W.0156.210812T1116Z-210812T1515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
416 AM MST Thu Aug 12 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  The Sears Fire Burn Scar in...
  Maricopa County in south central Arizona...

* Until 815 AM MST.

* At 416 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Sears Fire Burn Scar. Between 0.5 and 1.5 
  inches of rain have fallen. Additional rainfall amounts up to 0.5 
  inches 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 Camp Creek. 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 Sears Fire
           Burn Scar.

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  mainly rural areas of Maricopa County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3396 11177 3396 11169 3393 11165 3391 11163
      3386 11160 3379 11165 3378 11167 3379 11175
      3384 11179 3388 11180 3395 11180

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

$$

CK
2 follow-up statements
987 
WGUS75 KPSR 121208 RRA
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
508 AM MST Thu Aug 12 2021

AZC013-121515-
/O.CON.KPSR.FF.W.0156.000000T0000Z-210812T1515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
508 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING FOR THE SEARS FIRE BURN SCAR REMAINS IN 
EFFECT UNTIL 815 AM MST THIS MORNING FOR MARICOPA COUNTY...

At 508 AM MST, Doppler radar indicated thunderstorms producing heavy 
rain over the Sears Fire Burn Scar. Between 0.5 and 1.5 inches of 
rain have fallen. Additional rainfall amounts up to 0.5 inches 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 Camp Creek. 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 Sears Fire Burn Scar.

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
  mainly rural areas of Maricopa County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3396 11177 3396 11169 3393 11165 3391 11163
      3386 11160 3379 11165 3378 11167 3379 11175
      3384 11179 3388 11180 3395 11180

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

$$

CK
025 
WGUS75 KPSR 121507
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
807 AM MST Thu Aug 12 2021

AZC013-121517-
/O.EXP.KPSR.FF.W.0156.000000T0000Z-210812T1515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
807 AM MST Thu Aug 12 2021

...FLASH FLOOD WARNING FOR THE SEARS FIRE BURN SCAR WILL EXPIRE AT 
815 AM MST THIS MORNING 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 3396 11177 3396 11169 3393 11165 3391 11163
      3386 11160 3379 11165 3378 11167 3379 11175
      3384 11179 3388 11180 3395 11180

$$

INS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 11, 5:03 PM MSTSevere Thunderstorm WarningPSRMaricopa42 min
Aug 11, 5:14 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa3 hr
Aug 11, 5:14 PM MSTSpecial Weather StatementPSRMaricopa46 min
Aug 11, 5:30 PM MSTFlash Flood WarningPSRMaricopa2 hr
Aug 11, 5:30 PM MSTSevere Thunderstorm WarningPSRMaricopa, Pinal45 min
Aug 11, 5:39 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa3 hr
Aug 11, 5:49 PM MSTSpecial Weather StatementPSR41 min
Aug 11, 5:57 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Aug 11, 6:07 PM MSTDust Storm WarningPSRMaricopa, Pinal53 min
Aug 11, 6:12 PM MSTSevere Thunderstorm WarningPSRMaricopa, Pinal48 min
Aug 11, 6:19 PM MSTSevere Thunderstorm WarningPSRMaricopa41 min
Aug 11, 6:20 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 11, 6:40 PM MSTFlash Flood WarningPSRMaricopa4 hr
Aug 11, 7:02 PM MSTSpecial Weather StatementPSR58 min
Aug 11, 7:11 PM MSTSpecial Weather StatementPSR64 min
Aug 11, 7:26 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz3 hr
Aug 11, 7:53 PM MSTSpecial Weather StatementPSRLa Paz37 min
Aug 12, 2:00 AM MSTSpecial Weather StatementPSR45 min
Aug 12, 2:42 AM MSTFlash Flood Warning Considerable damage threatPSRGila, Maricopa4 hr
Aug 12, 2:45 AM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Aug 12, 3:34 AM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Aug 12, 4:33 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 12, 5:17 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa6 hr
Aug 12, 6:04 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 12, 6:21 AM MSTAreal Flood AdvisoryPSRMaricopa46 min
Aug 12, 7:00 AM MSTFlash Flood Warning Considerable damage threatPSRMaricopa4 hr
Aug 12, 10:09 AM MSTAreal Flood WarningPSRGila8 hr
Aug 12, 10:46 AM MSTAreal Flood WarningPSRMaricopa15 hr
Aug 12, 1:30 PM MSTFlash Flood WatchPSRGila, Maricopa, Pinal5 days
Aug 12, 2:11 PM MSTSpecial Weather StatementPSRLa Paz34 min
Aug 12, 2:30 PM MSTAreal Flood AdvisoryPSRMaricopa3 hr
Aug 12, 2:45 PM MSTAreal Flood AdvisoryPSRLa Paz3 hr
Aug 12, 2:54 PM MSTFlash Flood Warning Considerable damage threatPSRLa Paz, Maricopa4 hr
Aug 12, 3:11 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Aug 12, 3:34 PM MSTSpecial Weather StatementPSR41 min
Aug 12, 4:14 PM MSTAreal Flood AdvisoryPSRMaricopa, Yuma3 hr

Nearby

Flash Flood Warnings in Arizona, 2021Every 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.