Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 94, NWS Phoenix, AZ

July 25, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 25, 2021, 6:13 PM PDT for Riverside 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, 6:13 PM PDT (01:13 UTC)
Expired: Jul 25, 2021, 10:15 PM PDT
In force: 4 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Riverside County, CA

The radar

The Yuma radar (KYUX), 129 km from the middle of the area, began a volume at 01:15 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, 1.2 hours before the alert went out and 207 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.

049 
WGUS55 KPSR 260113
FFWPSR
CAC065-260515-
/O.NEW.KPSR.FF.W.0094.210726T0113Z-210726T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Riverside County in southern California...

* Until 1015 PM PDT.

* At 613 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 2 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...
  mainly rural areas of Riverside County

This includes the following highways...
	CA Interstate 10 between mile markers 111 and 120.

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 3364 11533 3371 11530 3376 11521 3376 11512
      3369 11504 3364 11502 3361 11500 3359 11499
      3354 11501 3348 11500 3346 11502 3344 11506
      3343 11512 3344 11525 3346 11531 3349 11535
      3354 11535 3357 11534 3361 11533

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

$$

Iniguez

2 follow-up statements

757 
WGUS75 KPSR 260337
FFSPSR

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

CAC065-260515-
/O.CON.KPSR.FF.W.0094.000000T0000Z-210726T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
837 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1015 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 837 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area, south of Interstate 10 near Ford Dry 
Lake. Between 1 and 3 inches of rain have 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...
  mainly rural areas of Riverside County

This includes the following highways and roads...
	CA Interstate 10 between mile markers 111 and 120.
    Chuckwalla Valley Road.

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 3364 11533 3371 11530 3376 11521 3376 11512
      3369 11504 3364 11502 3361 11500 3359 11499
      3354 11501 3348 11500 3346 11502 3344 11506
      3343 11512 3344 11525 3346 11531 3349 11535
      3354 11535 3357 11534 3361 11533

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

$$

Iniguez

555 
WGUS75 KPSR 260511 RRA
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1011 PM PDT Sun Jul 25 2021

CAC065-260521-
/O.EXP.KPSR.FF.W.0094.000000T0000Z-210726T0515Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
1011 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1015 PM PDT THIS EVENING FOR 
RIVERSIDE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3364 11533 3371 11530 3376 11521 3376 11512
      3369 11504 3364 11502 3361 11500 3359 11499
      3354 11501 3348 11500 3346 11502 3344 11506
      3343 11512 3344 11525 3346 11531 3349 11535
      3354 11535 3357 11534 3361 11533

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
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 25, 8:08 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.