Alert archive / California / Flash Flood Warnings in 2025

Flash Flood Warning 35, NWS Phoenix, AZ

September 4, 2025Imperial County, Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Sep 4, 2025, 3:25 PM PDT for Imperial County, 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 counties it named.

The facts

Issued: Sep 4, 2025, 3:25 PM PDT (22:25 UTC)
Expired: Sep 4, 2025, 7:30 PM PDT
In force: 4 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Imperial County, CA, Riverside County, CA

The radar

The San Diego radar (KNKX), 137 km from the middle of the area, began a volume at 22:25 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

Yuma Prvg Ground, AZ (K1Y7), launched 12:00Z, 10.4 hours before the alert went out and 155 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: 3019 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1052 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: -33 m²/s²
0-3 km storm-relative helicity: 15 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before this flash flood warning went out at Sep 4, 3:11 PM PDT, 14 minutes earlier.

Area forecast discussion, Sep 4, 3:11 PM PDT, 14 minutes before

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In the hours before

Special weather statement, Sep 4, 1:15 PM PDT, 2 hours 10 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
115 PM MST Thu Sep 4 2025

AZZ530-531-533-042100-
Kofa AZ-Parker Valley AZ-Central La Paz AZ-
115 PM MST Thu Sep 4 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN LA PAZ AND NORTH
CENTRAL YUMA COUNTIES THROUGH 200 PM MST...

At 115 PM MST, Doppler radar was tracking a strong thunderstorm 12
miles east of Yuma Proving Ground, or 19 miles northeast of Martinez
Lake, moving southeast at 10 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Kofa Wildlife Refuge, Palm Canyon, and Ehrenberg.

This includes the following highways...
AZ Interstate 10 near mile marker 4.
AZ Route 95 between mile markers 63 and 97.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 3342 11460 3362 11447 3345 11377 3297 11421
TIME...MOT...LOC 2015Z 302DEG 7KT 3313 11419

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

KB

Special weather statement, Sep 4, 3:04 PM PDT, 21 minutes before

Special Weather Statement
National Weather Service Phoenix AZ
304 PM MST Thu Sep 4 2025

AZZ530-531-CAZ564-569-570-042245-
Kofa AZ-Parker Valley AZ-Chuckwalla Mountains CA-
Palo Verde Valley CA-Chuckwalla Valley CA-
304 PM MST Thu Sep 4 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN LA PAZ...
NORTHEASTERN IMPERIAL AND RIVERSIDE COUNTIES THROUGH 345 PM MST/345
PM PDT/...

At 303 PM MST/303 PM PDT/, Doppler radar was tracking a strong
thunderstorm 13 miles southwest of Palo Verde, or 35 miles northwest
of Martinez Lake, moving southeast at 10 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Cibola and Palo Verde.

This includes CA Route 78 between mile markers 55 and 80.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3327 11443 3302 11473 3336 11533 3359 11503
TIME...MOT...LOC 2203Z 316DEG 7KT 3332 11492

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

KB

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 3, 5:34 PM PDT	Dust Storm Advisory	PSR	Pinal	86 min
Sep 3, 5:42 PM PDT	Special Weather Statement	PSR	La Paz	48 min
Sep 3, 6:15 PM PDT	Special Weather Statement	PSR	La Paz	45 min
Sep 3, 6:52 PM PDT	Dust Storm Advisory	PSR	Maricopa, Pinal	53 min
Sep 3, 7:01 PM PDT	Severe Thunderstorm Warning	PSR	Pinal	29 min
Sep 3, 7:08 PM PDT	Severe Thunderstorm Warning	PSR	Yuma	37 min
Sep 3, 7:43 PM PDT	Severe Thunderstorm Warning	PSR	Pinal	47 min
Sep 3, 8:08 PM PDT	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	52 min
Sep 3, 8:14 PM PDT	Dust Storm Warning	PSR	Maricopa, Pinal	46 min
Sep 3, 8:39 PM PDT	Dust Storm Advisory	PSR	Maricopa	66 min
Sep 3, 8:40 PM PDT	Severe Thunderstorm Warning	PSR	Maricopa	35 min
Sep 3, 8:52 PM PDT	Dust Storm Advisory	PSR	Maricopa, Pinal	53 min
Sep 3, 8:54 PM PDT	Flash Flood Warning	PSR	Maricopa	111 min
Sep 3, 8:59 PM PDT	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	46 min
Sep 3, 9:07 PM PDT	Severe Thunderstorm Warning	PSR	Maricopa, Pinal	53 min
Sep 3, 9:18 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Maricopa, Pinal	3 hr
Sep 3, 9:20 PM PDT	Severe Thunderstorm Warning	PSR	Pinal	25 min
Sep 3, 9:25 PM PDT	Special Weather Statement	PSR		50 min
Sep 3, 9:48 PM PDT	Areal Flood Advisory	PSR	Maricopa, Pinal	3 hr
Sep 3, 10:53 PM PDT	Areal Flood Advisory	PSR	Maricopa	3 hr
Sep 3, 11:26 PM PDT	Areal Flood Advisory	PSR	Maricopa	2 hr
Sep 4, 12:11 AM PDT	Areal Flood Warning	PSR	Maricopa	3 hr
Sep 4, 12:20 AM PDT	Special Weather Statement	PSR	Maricopa	40 min
Sep 4, 1:01 AM PDT	Areal Flood Advisory	PSR	Maricopa	119 min
Sep 4, 2:49 AM PDT	Areal Flood Advisory	PSR	Maricopa	116 min
Sep 4, 1:15 PM PDT	Special Weather Statement	PSR	La Paz	45 min
Sep 4, 1:35 PM PDT	Areal Flood Advisory	PSR	La Paz, Yuma	9 min
Sep 4, 1:44 PM PDT	Flash Flood Warning Considerable damage threat	PSR	La Paz, Yuma	3 hr
Sep 4, 2:10 PM PDT	Severe Thunderstorm Warning	PSR	La Paz	50 min
Sep 4, 2:21 PM PDT	Areal Flood Advisory	PSR	La Paz	12 min
Sep 4, 2:31 PM PDT	Flash Flood Warning Considerable damage threat	PSR	La Paz	3 hr
Sep 4, 2:44 PM PDT	Dust Storm Advisory	PSR	Pinal	61 min
Sep 4, 2:48 PM PDT	Severe Thunderstorm Warning	PSR	La Paz	42 min
Sep 4, 3:29 PM PDT	Dust Storm Advisory	PSR	Maricopa, Pinal	46 min
Sep 4, 3:50 PM PDT	Special Weather Statement	PSR		40 min
Sep 4, 4:13 PM PDT	Dust Storm Advisory	PSR	Maricopa, Pinal	47 min
Sep 4, 4:23 PM PDT	Areal Flood Advisory	PSR	Maricopa	3 hr
Sep 4, 4:26 PM PDT	Flash Flood Warning Considerable damage threat	PSR	La Paz	4 hr
Sep 4, 3:04 PM PDT	Special Weather Statement	PSR	Imperial	41 min
Sep 4, 3:41 PM PDT	Special Weather Statement	PSR	Imperial	49 min
Sep 4, 4:37 PM PDT	Special Weather Statement	PSR	Imperial	38 min

Nearby

Flash Flood Warnings in California, 2025 Every flash flood warning in 2025

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.