Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 99, NWS Phoenix, AZ

July 25, 2021Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 25, 2021, 8:08 PM PDT for Imperial County, California. 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 25, 2021, 8:08 PM PDT (03:08 UTC)
Expired: Jul 26, 2021, 12:15 AM PDT
In force: 4 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), 80 km from the middle of the area, began a volume at 03:12 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

San Diego, CA (KNKX), launched 00:00Z, 3.1 hours before the alert went out and 218 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: 1166 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 36 m²/s²
0-3 km storm-relative helicity: 90 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

748 
WGUS55 KPSR 260308
FFWPSR
CAC025-260715-
/O.NEW.KPSR.FF.W.0099.210726T0308Z-210726T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
808 PM PDT Sun Jul 25 2021

The National Weather Service in Phoenix has issued a

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

* Until 1215 AM PDT.

* At 808 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 2 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly especially along CA Route 78 between Glamis and Palo Verde.

  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...
  mainly rural areas of East Central Imperial County

This includes the following highways...
	CA Route 78 between mile markers 51 and 60.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3324 11494 3326 11486 3326 11484 3324 11482
      3323 11481 3319 11480 3313 11482 3308 11486
      3307 11497 3308 11498 3311 11499 3316 11498
      3321 11498 3323 11497 3324 11496

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

$$

Iniguez

2 follow-up statements

507 
WGUS75 KPSR 260424
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
924 PM PDT Sun Jul 25 2021

CAC025-260715-
/O.CON.KPSR.FF.W.0099.000000T0000Z-210726T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
924 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1215 AM PDT MONDAY 
FOR EAST CENTRAL IMPERIAL COUNTY...

At 924 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.5 and 2 inches of rain have 
fallen. Flash flooding is ongoing or expected to begin shortly 
especially along CA Route 78 between Glamis and Palo Verde.

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...
  mainly rural areas of East Central Imperial County

This includes the following highways...
	CA Route 78 between mile markers 51 and 60.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3324 11494 3326 11486 3326 11484 3324 11482
      3323 11481 3319 11480 3313 11482 3308 11486
      3307 11497 3308 11498 3311 11499 3316 11498
      3321 11498 3323 11497 3324 11496

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

$$

Iniguez

411 
WGUS75 KPSR 260710
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1210 AM PDT Mon Jul 26 2021

CAC025-260720-
/O.EXP.KPSR.FF.W.0099.000000T0000Z-210726T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
1210 AM PDT Mon Jul 26 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1215 AM PDT EARLY THIS MORNING 
FOR EAST CENTRAL IMPERIAL 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 3324 11494 3326 11486 3326 11484 3324 11482
      3323 11481 3319 11480 3313 11482 3308 11486
      3307 11497 3308 11498 3311 11499 3316 11498
      3321 11498 3323 11497 3324 11496

$$

CK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 6:13 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	4 hr
Jul 25, 6:35 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	4 hr
Jul 25, 6:54 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial	4 hr
Jul 26, 1:52 AM PDT	Areal Flood Advisory	PSR	Imperial	3 hr
Jul 26, 3:36 AM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	6 hr
Jul 26, 6:49 AM PDT	Areal Flood Advisory	PSR	Riverside	3 hr
Jul 26, 8:01 AM PDT	Areal Flood Advisory	PSR	Riverside, San Bernardino	3 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.