Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 54, NWS Phoenix, AZ

July 22, 2021Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Jul 22, 2021, 12:28 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
Jul 22, 2021, 12:28 AM MST (07:28 UTC)
Expired
Jul 22, 2021, 4:30 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), 70 km from the middle of the area, began a volume at 07:30 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, 7.5 hours before the alert went out and 57 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 2021-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 760 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -21 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
760 J/kg
Mixed-layer CIN
-12 J/kg
Mixed-layer LCL
3156 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-21 m²/s²
0-3 km storm-relative helicity
10 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

As transmitted.

463 
WGUS55 KPSR 220728
FFWPSR
AZC013-221130-
/O.NEW.KPSR.FF.W.0054.210722T0728Z-210722T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1228 AM MST Thu Jul 22 2021

The National Weather Service in Phoenix has issued a

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

* Until 430 AM MST.

* At 1228 AM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Sears Burn Scar. Between 0.5 and 1.5 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

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

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  Scottsdale and Camp Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

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

&&

LAT...LON 3397 11171 3398 11166 3386 11167 3383 11171
      3384 11176 3387 11184 3392 11185 3396 11182

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

$$

18
3 follow-up statements
983 
WGUS75 KPSR 220831
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
131 AM MST Thu Jul 22 2021

AZC013-221130-
/O.CON.KPSR.FF.W.0054.000000T0000Z-210722T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
131 AM MST Thu Jul 22 2021

...FLASH FLOOD WARNING FOR THE SEARS BURN SCAR REMAINS IN EFFECT 
UNTIL 430 AM MST EARLY THIS MORNING FOR MARICOPA COUNTY...

At 131 AM MST, Doppler radar indicated thunderstorms have produced 
heavy rain over the Sears Burn Scar. Between 1 and 2 inches of rain 
have fallen. Flash flooding is ongoing or expected to begin shortly.

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

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
  Scottsdale and Camp Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

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

&&

LAT...LON 3397 11171 3398 11166 3386 11167 3383 11171
      3384 11176 3387 11184 3392 11185 3396 11182

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

$$

18
113 
WGUS75 KPSR 221014
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
314 AM MST Thu Jul 22 2021

AZC013-221130-
/O.CON.KPSR.FF.W.0054.000000T0000Z-210722T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
314 AM MST Thu Jul 22 2021

...FLASH FLOOD WARNING FOR THE SEARS BURN SCAR REMAINS IN EFFECT 
UNTIL 430 AM MST EARLY THIS MORNING FOR MARICOPA COUNTY...

At 314 AM MST, Doppler radar indicated thunderstorms have produced 
heavy rain over the Sears Burn Scar. Between 1 and 2 inches of rain 
have fallen. Flash flooding is ongoing or expected to begin shortly.

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

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
  Scottsdale and Camp Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

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

&&

LAT...LON 3397 11171 3398 11166 3386 11167 3383 11171
      3384 11176 3387 11184 3392 11185 3396 11182

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

$$

18
904 
WGUS75 KPSR 221125
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
425 AM MST Thu Jul 22 2021

AZC013-221135-
/O.EXP.KPSR.FF.W.0054.000000T0000Z-210722T1130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Maricopa AZ-
425 AM MST Thu Jul 22 2021

...FLASH FLOOD WARNING FOR THE SEARS BURN SCAR WILL EXPIRE AT 430 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 3397 11171 3398 11166 3386 11167 3383 11171
      3384 11176 3387 11184 3392 11185 3396 11182

$$

18

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 5:37 PM MSTSpecial Weather StatementPSRYuma38 min
Jul 21, 5:41 PM MSTSpecial Weather StatementPSR49 min
Jul 21, 6:18 PM MSTSevere Thunderstorm WarningPSRLa Paz, Yuma42 min
Jul 21, 6:20 PM MSTSpecial Weather StatementPSRGila40 min
Jul 21, 6:47 PM MSTSpecial Weather StatementPSR43 min
Jul 21, 6:59 PM MSTSpecial Weather StatementPSRYuma46 min
Jul 21, 7:06 PM MSTAreal Flood AdvisoryPSRGila3 hr
Jul 21, 7:10 PM MSTSpecial Weather StatementPSRLa Paz50 min
Jul 21, 7:17 PM MSTAreal Flood AdvisoryPSRYuma44 min
Jul 21, 7:40 PM MSTDust Storm WarningPSRYuma35 min
Jul 21, 8:01 PM MSTFlash Flood Warning Considerable damage threatPSRYuma4 hr
Jul 21, 8:13 PM MSTDust Storm AdvisoryPSRYuma47 min
Jul 21, 9:06 PM MSTDust Storm AdvisoryPSRMaricopa, Pinal39 min
Jul 21, 10:06 PM MSTDust Storm AdvisoryPSRMaricopa, Pinal39 min
Jul 21, 10:11 PM MSTSpecial Weather StatementPSRPinal49 min
Jul 21, 10:23 PM MSTSpecial Weather StatementPSRMaricopa37 min
Jul 21, 10:25 PM MSTSevere Thunderstorm WarningPSRMaricopa16 min
Jul 21, 10:39 PM MSTSpecial Weather StatementPSR36 min
Jul 21, 10:51 PM MSTSevere Thunderstorm WarningPSRMaricopa24 min
Jul 21, 11:12 PM MSTSpecial Weather StatementPSR48 min
Jul 21, 11:15 PM MSTSpecial Weather StatementPSRPinal45 min
Jul 22, 12:32 AM MSTAreal Flood AdvisoryPSRMaricopa118 min
Jul 22, 3:06 PM MSTSpecial Weather StatementPSR54 min
Jul 22, 3:43 PM MSTSpecial Weather StatementPSRMaricopa47 min
Jul 22, 3:58 PM MSTSevere Thunderstorm WarningPSRMaricopa33 min
Jul 22, 4:30 PM MSTDust Storm AdvisoryPSRYuma41 min
Jul 22, 4:53 PM MSTAreal Flood AdvisoryPSRMaricopa3 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.