Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 238, NWS Phoenix, AZ

August 31, 2021Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 31, 2021, 7:41 PM PDT for Imperial County, California. It was in force for 8 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 31, 2021, 7:41 PM PDT (02:41 UTC)
Expired: Sep 1, 2021, 3:45 AM PDT
In force: 8 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Imperial County, CA

The radar

The Yuma radar (KYUX), 79 km from the middle of the area, began a volume at 02:44 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 31, 9:25 PM PDT	FLASH FLOOD	2 Wnw Calexico, CA	COLE ROAD AT DOGWOOD ROAD 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

Yuma Prvg Ground, AZ (K1Y7), launched 00:00Z, 2.7 hours before the alert went out and 102 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: 1759 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 1368 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

907 
WGUS55 KPSR 010241
FFWPSR
CAC025-011045-
/O.NEW.KPSR.FF.W.0238.210901T0241Z-210901T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
741 PM PDT Tue Aug 31 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  South Central Imperial County in southeastern California...

* Until 345 AM PDT Wednesday.

* At 741 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain in the Imperial Valley including Calexico and 
  Holtville. Between 0.5 and 1 inch of rain has fallen. Additional 
  rainfall amounts of 0.5 to 1 inch 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...
  Calexico, Holtville, Mt. Signal, Gordon's Well, Bonds Corner and 
  Heber.

This includes the following highways...
	CA Route 86 between mile markers 1 and 2.
	CA Route 98 between mile markers 14 and 23.
	CA Interstate 8 between mile markers 42 and 51.
	CA Route 111 between mile markers 1 and 6.

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 3264 11578 3267 11584 3274 11551 3294 11537
      3286 11507 3270 11495 3270 11500 3268 11525
      3267 11538 3267 11547 3267 11549 3266 11550
      3265 11563 3265 11566 3265 11575

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

$$

Hirsch

2 follow-up statements

566 
WGUS75 KPSR 010331
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
831 PM PDT Tue Aug 31 2021

CAC025-011045-
/O.CON.KPSR.FF.W.0238.000000T0000Z-210901T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
831 PM PDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 AM PDT WEDNESDAY 
FOR SOUTH CENTRAL IMPERIAL COUNTY...

At 831 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain in Imperial Valley including Calexico and Holtville. Up to 1.5 
inches of rain has fallen. Additional rainfall amounts up to 1 inch 
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...
  Calexico, Holtville, Mt. Signal, Gordon's Well, Bonds Corner and 
  Heber.

This includes the following highways...
	CA Route 86 between mile markers 1 and 3.
	CA Route 98 between mile markers 14 and 23.
	CA Interstate 8 between mile markers 42 and 51.
	CA Route 111 between mile markers 1 and 6.

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 3264 11578 3267 11584 3274 11551 3294 11537
      3286 11507 3270 11495 3270 11500 3268 11525
      3267 11538 3267 11547 3267 11549 3266 11550
      3265 11563 3265 11566 3265 11575

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

$$

CK

530 
WGUS75 KPSR 011038
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
338 AM PDT Wed Sep 1 2021

CAC025-011048-
/O.EXP.KPSR.FF.W.0238.000000T0000Z-210901T1045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
338 AM PDT Wed Sep 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 345 AM PDT EARLY THIS MORNING 
FOR SOUTH CENTRAL IMPERIAL COUNTY...

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

LAT...LON 3264 11578 3267 11584 3274 11551 3294 11537
      3286 11507 3270 11495 3270 11500 3268 11525
      3267 11538 3267 11547 3267 11549 3266 11550
      3265 11563 3265 11566 3265 11575

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 31, 5:12 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial, Riverside	6 hr
Aug 31, 5:58 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial, Riverside	8 hr

Nearby

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.