Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 89, NWS Phoenix, AZ

July 25, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 25, 2021, 2:34 PM PDT for Riverside County, California. It was in force for 7 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, 2:34 PM PDT (21:34 UTC)
Expired
Jul 25, 2021, 9:45 PM PDT
In force
7 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), 152 km from the middle of the area, began a volume at 21:36 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 12:00Z, 9.6 hours before the alert went out and 175 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-pSkew-T log-p diagram, San Diego, CA at 12:00Z on 2021-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2021-07-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -1 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
1039 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
-1 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.

852 
WGUS55 KPSR 252134
FFWPSR
CAC065-260145-
/O.NEW.KPSR.FF.W.0089.210725T2134Z-210726T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
234 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 645 PM PDT.

* At 234 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1.5 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...
  mainly rural areas of Riverside County

This includes the following highways...
	CA Interstate 10 between mile markers 88 and 97.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3370 11574 3375 11556 3369 11550 3364 11546
      3358 11533 3353 11537 3350 11550 3349 11572
      3358 11575 3361 11575 3364 11568

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

$$

MS
3 follow-up statements
045 
WGUS75 KPSR 260118
FFSPSR

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

CAC065-260145-
/O.CON.KPSR.FF.W.0089.000000T0000Z-210726T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
618 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 645 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 618 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 0.5 and 1.5 inches of rain have 
fallen. Additional thunderstorms are moving into the warned area 
which may produce additional rainfall amounts up to 1.5 inches. 
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 88 and 97.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3370 11574 3375 11556 3369 11550 3364 11546
      3358 11533 3353 11537 3350 11550 3349 11572
      3358 11575 3361 11575 3364 11568

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

$$

Iniguez
769 
WGUS55 KPSR 260138
FFWPSR
CAC065-260445-
/O.EXT.KPSR.FF.W.0089.000000T0000Z-210726T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Phoenix has extended the

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

* Until 945 PM PDT.

* At 638 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1.5 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...
  mainly rural areas of Riverside County

This includes the following highways...
	CA Interstate 10 between mile markers 88 and 97.

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 3370 11574 3375 11556 3369 11550 3364 11546
      3358 11533 3353 11537 3350 11550 3349 11572
      3358 11575 3361 11575 3364 11568

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

$$

Iniguez
156 
WGUS75 KPSR 260441
FFSPSR

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

CAC065-260451-
/O.EXP.KPSR.FF.W.0089.000000T0000Z-210726T0445Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
941 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 945 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 3370 11574 3375 11556 3369 11550 3364 11546
      3358 11533 3353 11537 3350 11550 3349 11572
      3358 11575 3361 11575 3364 11568

$$

Iniguez

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 11:59 AM PDTSpecial Weather StatementPSRRiverside31 min
Jul 25, 12:14 PM PDTFlash Flood Warning Considerable damage threatPSRRiverside4 hr
Jul 25, 12:43 PM PDTSpecial Weather StatementPSRRiverside32 min
Jul 25, 1:12 PM PDTFlash Flood Warning Considerable damage threatPSRRiverside4 hr
Jul 25, 1:24 PM PDTSpecial Weather StatementPSRRiverside51 min
Jul 25, 2:15 PM PDTSpecial Weather StatementPSRRiverside45 min
Jul 25, 2:38 PM PDTSpecial Weather StatementPSRRiverside37 min
Jul 25, 3:14 PM PDTSpecial Weather StatementPSRRiverside31 min
Jul 25, 3:20 PM PDTFlash Flood Warning Considerable damage threatPSRRiverside5 hr
Jul 25, 3:41 PM PDTSpecial Weather StatementPSRRiverside34 min
Jul 25, 4:01 PM PDTSevere Thunderstorm WarningPSRRiverside, San Bernardino29 min
Jul 25, 4:18 PM PDTFlash Flood Warning Considerable damage threatPSRRiverside4 hr

Nearby

Flash Flood Warnings in California, 2021Every 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.