Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 227, NWS Phoenix, AZ

August 18, 2021Gila County, Arizona

NWS Phoenix, AZ issued this flash flood warning at Aug 18, 2021, 6:20 PM MST for Gila 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: Aug 18, 2021, 6:20 PM MST (01:20 UTC)
Expired: Aug 18, 2021, 10:30 PM MST
In force: 4 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Gila County, AZ

The radar

The Phoenix radar (KIWA), 108 km from the middle of the area, began a volume at 01:24 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

Tuscon, AZ (KTUS), launched 00:00Z, 1.3 hours before the alert went out and 127 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: 802 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 2035 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 53 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

As transmitted.

583 
WGUS55 KPSR 190120
FFWPSR
AZC007-190530-
/O.NEW.KPSR.FF.W.0227.210819T0120Z-210819T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
620 PM MST Wed Aug 18 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Gila County in east central Arizona...

* Until 1030 PM MST.

* At 620 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  San Carlos and Peridot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3315 11055 3327 11061 3331 11062 3334 11053
      3334 11049 3335 11047 3337 11046 3337 11045
      3336 11045 3335 11044 3330 11045 3329 11046
      3328 11045 3318 11048 3319 11050 3318 11053
      3317 11053 3316 11053 3317 11054

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

$$

AD

1 follow-up statement

161 
WGUS75 KPSR 190526
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1026 PM MST Wed Aug 18 2021

AZC007-190536-
/O.EXP.KPSR.FF.W.0227.000000T0000Z-210819T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Gila AZ-
1026 PM MST Wed Aug 18 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1030 PM MST THIS EVENING FOR 
GILA COUNTY...

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

LAT...LON 3315 11055 3327 11061 3331 11062 3334 11053
      3334 11049 3335 11047 3337 11046 3337 11045
      3336 11045 3335 11044 3330 11045 3329 11046
      3328 11045 3318 11048 3319 11050 3318 11053
      3317 11053 3316 11053 3317 11054

$$

CK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 5:13 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Aug 18, 5:20 PM MST	Special Weather Statement	PSR	Gila	40 min
Aug 18, 5:25 PM MST	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	50 min
Aug 18, 5:34 PM MST	Special Weather Statement	PSR		41 min
Aug 18, 5:39 PM MST	Flash Flood Warning Considerable damage threat	PSR	Gila	4 hr
Aug 18, 5:40 PM MST	Special Weather Statement	PSR	Maricopa	50 min
Aug 18, 5:43 PM MST	Severe Thunderstorm Warning	PSR	Maricopa	32 min
Aug 18, 5:52 PM MST	Special Weather Statement	PSR		38 min
Aug 18, 6:09 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	3 hr
Aug 18, 6:14 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 18, 6:36 PM MST	Special Weather Statement	PSR		39 min
Aug 18, 7:20 PM MST	Areal Flood Warning	PSR	Maricopa	6 hr
Aug 18, 7:33 PM MST	Areal Flood Warning	PSR	Maricopa	6 hr
Aug 18, 7:33 PM MST	Areal Flood Warning	PSR	Maricopa	6 hr
Aug 18, 8:57 PM MST	Areal Flood Warning	PSR	Maricopa	14 hr

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.