Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 138, NWS Phoenix, AZ

August 10, 2021La Paz County, Yuma County, Arizona; Imperial County, Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 10, 2021, 9:08 PM MST for La Paz County, Yuma County, Arizona; Imperial County, Riverside County, California. It was in force for 6 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 10, 2021, 9:08 PM MST (04:08 UTC)
Expired: Aug 11, 2021, 3:00 AM MST
In force: 6 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties La Paz County, AZ, Yuma County, AZ, Imperial County, CA, Riverside County, CA

The radar

The Yuma radar (KYUX), 96 km from the middle of the area, began a volume at 04:09 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

Time	Report	Where	Remark
Aug 10, 11:37 PM MST	FLASH FLOOD	5 S Palo Verde, CA	HIGHWAY 78 CLOSED DUE TO FLOODING.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 00:00Z, 4.1 hours before the alert went out and 247 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 3091 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 54 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

661 
WGUS55 KPSR 110408
FFWPSR
AZC012-027-CAC025-065-111000-
/O.NEW.KPSR.FF.W.0138.210811T0408Z-210811T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
908 PM MST Tue Aug 10 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  North Central Yuma County in southwestern Arizona...
  Southwestern La Paz County in west central Arizona...
  Northeastern Imperial County in southeastern California...
  Riverside County in southern California...

* Until 300 AM MST /300 AM PDT/.

* At 908 PM MST /908 PM PDT/, Doppler radar indicated thunderstorms 
  producing heavy rain across the warned area. Between 1 and 2.5 
  inches of rain have fallen. Additional rainfall amounts up to 1.5 
  inches are possible in 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...
  Blythe, Cibola, Palo Verde and Yuma Proving Ground.

This includes the following highways...
	CA Interstate 10 between mile markers 125 and 134.
	CA Route 78 between mile markers 61 and 70.
	AZ Route 95 between mile markers 66 and 75.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3344 11529 3359 11520 3365 11504 3360 11486
      3357 11468 3348 11468 3344 11451 3332 11430
      3330 11426 3329 11424 3321 11416 3318 11416
      3316 11419 3308 11436 3311 11459 3324 11498

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

$$

Hirsch

2 follow-up statements

073 
WGUS75 KPSR 110727
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1227 AM MST Wed Aug 11 2021

AZC012-027-CAC025-065-111000-
/O.CON.KPSR.FF.W.0138.000000T0000Z-210811T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
La Paz AZ-Yuma AZ-Imperial CA-Riverside CA-
1227 AM MST Wed Aug 11 2021 /1227 AM PDT Wed Aug 11 2021/

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 AM MST/3 AM PDT/ 
EARLY THIS MORNING FOR NORTH CENTRAL YUMA, SOUTHWESTERN LA PAZ, 
NORTHEASTERN IMPERIAL AND RIVERSIDE COUNTIES...

At 1227 AM MST /1227 AM PDT/, Doppler radar indicated thunderstorms 
produced heavy rain across the warned area. Between 1 and 2.5 inches 
of rain have fallen. 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...
  Blythe, Cibola, Palo Verde and Yuma Proving Ground.

This includes the following highways...
	CA Interstate 10 between mile markers 125 and 134.
	CA Route 78 between mile markers 62 and 71.
	AZ Route 95 between mile markers 66 and 75.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3344 11529 3359 11520 3365 11504 3360 11486
      3357 11468 3348 11468 3344 11451 3332 11430
      3330 11426 3329 11424 3321 11416 3318 11416
      3316 11419 3308 11436 3311 11459 3324 11498

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

$$

CK

586 
WGUS75 KPSR 111000
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
300 AM MST Wed Aug 11 2021

AZC012-027-CAC025-065-111010-
/O.EXP.KPSR.FF.W.0138.000000T0000Z-210811T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
La Paz AZ-Yuma AZ-Imperial CA-Riverside CA-
300 AM MST Wed Aug 11 2021 /300 AM PDT Wed Aug 11 2021/

...FLASH FLOOD WARNING HAS EXPIRED FOR NORTH CENTRAL YUMA, 
SOUTHWESTERN LA PAZ, NORTHEASTERN IMPERIAL AND RIVERSIDE 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.

LAT...LON 3344 11529 3359 11520 3365 11504 3360 11486
      3357 11468 3348 11468 3344 11451 3332 11430
      3330 11426 3329 11424 3321 11416 3318 11416
      3316 11419 3308 11436 3311 11459 3324 11498

$$

CK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 5:23 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 10, 5:35 PM MST	Special Weather Statement	PSR		40 min
Aug 10, 5:51 PM MST	Areal Flood Advisory	PSR	La Paz	3 hr
Aug 10, 5:55 PM MST	Special Weather Statement	PSR	La Paz	50 min
Aug 10, 6:30 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Yuma	45 min
Aug 10, 6:36 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Maricopa	4 hr
Aug 10, 7:15 PM MST	Dust Storm Warning	PSR	La Paz, Yuma	60 min
Aug 10, 7:26 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Maricopa, Yuma	49 min
Aug 10, 7:33 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Yuma	4 hr
Aug 10, 7:43 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal, Yuma	62 min
Aug 10, 8:18 PM MST	Severe Thunderstorm Warning	PSR	La Paz, Yuma	57 min
Aug 10, 8:38 PM MST	Dust Storm Warning	PSR	La Paz, Yuma	52 min
Aug 10, 9:12 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Yuma	6 hr
Aug 10, 9:23 PM MST	Special Weather Statement	PSR	Yuma	97 min
Aug 10, 9:42 PM MST	Dust Storm Warning	PSR	Yuma	93 min
Aug 10, 10:35 PM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Maricopa, Yuma	6 hr
Aug 11, 12:01 AM MST	Flash Flood Warning Considerable damage threat	PSR	La Paz, Yuma	5 hr
Aug 11, 2:00 AM MST	Areal Flood Advisory	PSR	Gila	3 hr
Aug 11, 3:29 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 4:33 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Aug 11, 6:06 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 6:11 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Aug 11, 6:15 AM MST	Areal Flood Advisory	PSR	Gila, Maricopa	3 hr
Aug 11, 7:30 AM MST	Flash Flood Warning Considerable damage threat	PSR	Gila, Maricopa	6 hr
Aug 11, 7:46 AM MST	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Aug 11, 8:12 AM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	6 hr
Aug 11, 9:13 AM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 1:01 PM MST	Special Weather Statement	PSR	Yuma	59 min
Aug 11, 1:29 PM MST	Areal Flood Warning	PSR	Maricopa	6 hr
Aug 11, 1:43 PM MST	Areal Flood Warning	PSR	Gila	4 hr
Aug 11, 1:49 PM MST	Areal Flood Advisory	PSR	Yuma	3 hr
Aug 11, 2:01 PM MST	Dust Storm Advisory	PSR	Yuma	59 min
Aug 11, 2:17 PM MST	Severe Thunderstorm Warning	PSR	Yuma	43 min
Aug 11, 3:02 PM MST	Flash Flood Warning Considerable damage threat	PSR	Yuma	4 hr
Aug 11, 3:11 PM MST	Special Weather Statement	PSR		64 min
Aug 11, 3:29 PM MST	Special Weather Statement	PSR	Maricopa	46 min
Aug 11, 3:34 PM MST	Special Weather Statement	PSR		56 min
Aug 11, 3:44 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 3:47 PM MST	Areal Flood Advisory	PSR	Maricopa	14 min
Aug 11, 3:50 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 4:01 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 11, 4:33 PM MST	Areal Flood Advisory	PSR	Maricopa	3 hr
Aug 11, 4:44 PM MST	Dust Storm Advisory	PSR	Maricopa, Pinal	61 min
Aug 11, 4:56 PM MST	Flash Flood Warning Considerable damage threat	PSR	Maricopa	3 hr
Aug 10, 9:54 PM MST	Flash Flood Warning Considerable damage threat	PSR	Riverside	86 min
Aug 10, 11:16 PM MST	Special Weather Statement	PSR	Imperial	74 min

Nearby

Flash Flood Warnings in Arizona, 2021 Flash Flood Warnings in California, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.