Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 242, NWS Phoenix, AZ

September 1, 2021Gila County, Maricopa County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Sep 1, 2021, 7:18 PM MST for Gila County, Maricopa County, Arizona. It was in force for 88 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Sep 1, 2021, 7:18 PM MST (02:18 UTC)
Expired
Sep 1, 2021, 8:46 PM MST
In force
88 min
Issued by
NWS Phoenix, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Gila County, AZ, Maricopa County, AZ

The radar

The Phoenix radar (KIWA), 59 km from the middle of the area, began a volume at 02:18 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, 2.3 hours before the alert went out and 61 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 2021-09-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 518 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 2021-09-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.193958Sfc1 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
518 J/kg
Mixed-layer CIN
-9 J/kg
Mixed-layer LCL
1794 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
65 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

820 
WGUS55 KPSR 020218
FFWPSR
AZC007-013-021015-
/O.NEW.KPSR.FF.W.0242.210902T0218Z-210902T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
718 PM MST Wed Sep 1 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  The Bush burn scar in...
  Gila County in east central Arizona...
  Maricopa County in south central Arizona...

* Until 315 AM MST Thursday.

* At 718 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain over the Bush Burn Scar. Between 0.5 and 1 inch of rain 
  has 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 Bush 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 Bush Burn
           Scar.

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  Ballantine Trailhead, Round Valley, Sugarloaf Mountain, Sunflower 
  and Rio Verde.

This includes the following streams and drainages...
  Picadilla Creek, Verde River, Boulder Creek, Mesquite Wash, Camp 
  Creek, South Fork Sheep Creek, Salt River, Indian Spring Wash, 
  Sycamore Creek, Cottonwood Creek and Ironwood Wash.

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 Bush 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 3369 11132 3364 11153 3377 11177 3393 11157
      3393 11149 3385 11139 3384 11139

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

$$

Hirsch
1 follow-up statement
661 
WGUS75 KPSR 020346
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
846 PM MST Wed Sep 1 2021

AZC007-013-020356-
/O.CAN.KPSR.FF.W.0242.000000T0000Z-210902T1015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Gila AZ-Maricopa AZ-
846 PM MST Wed Sep 1 2021

...FLASH FLOOD WARNING FOR THE BUSH BURN SCAR IS CANCELLED FOR GILA 
AND MARICOPA COUNTIES...

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.

A Flash Flood Watch remains in effect until 500 AM MST Thursday for 
portions of south central Arizona and southwest Arizona.

LAT...LON 3369 11132 3364 11153 3377 11177 3393 11157
      3393 11149 3385 11139 3384 11139

$$

Hirsch

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 1, 5:17 PM MSTSpecial Weather StatementPSR58 min
Sep 1, 5:45 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa3 hr
Sep 1, 9:35 PM MSTAreal Flood AdvisoryPSRMaricopa, Pinal6 hr
Sep 1, 10:09 PM MSTFlash Flood Warning Considerable damage threatPSRMaricopa5 hr
Sep 1, 11:09 PM MSTAreal Flood AdvisoryPSRMaricopa, Pinal7 hr
Sep 2, 12:41 AM MSTAreal Flood AdvisoryPSRMaricopa, Pinal3 hr
Sep 2, 1:52 AM MSTAreal Flood AdvisoryPSRPinal3 hr
Sep 2, 5:22 AM MSTAreal Flood AdvisoryPSRPinal4 hr
Sep 2, 6:11 AM MSTAreal Flood AdvisoryPSRMaricopa, Pinal3 hr
Sep 2, 3:25 PM MSTSpecial Weather StatementPSRMaricopa65 min
Sep 2, 3:51 PM MSTAreal Flood AdvisoryPSRMaricopa, Pinal3 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.