Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 140, NWS Phoenix, AZ

August 10, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 10, 2021, 9:54 PM PDT for Riverside County, California. It was in force for 86 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 10, 2021, 9:54 PM PDT (04:54 UTC)
Expired
Aug 10, 2021, 11:20 PM PDT
In force
86 min
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), 151 km from the middle of the area, began a volume at 04:57 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, 4.9 hours before the alert went out and 210 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 00:00Z on 2021-08-11Temperature 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 00:00Z on 2021-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 21 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
3091 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
21 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.

300 
WGUS55 KPSR 110454
FFWPSR
CAC065-111100-
/O.NEW.KPSR.FF.W.0140.210811T0454Z-210811T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
954 PM PDT Tue Aug 10 2021

The National Weather Service in Phoenix has issued a

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

* Until 400 AM PDT Wednesday.

* At 954 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 2 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...
  Desert Center.

This includes the following highways...
	CA Route 177 near mile marker 1...and
	between mile markers 10 and 13...and
	between mile markers 2 and 6.
	CA Interstate 10 between mile markers 102 and 111.

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 3385 11513 3380 11508 3370 11506 3359 11520
      3355 11537 3365 11548 3378 11544 3382 11539
      3386 11530 3385 11521

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

$$

Hirsch
1 follow-up statement
248 
WGUS75 KPSR 110620
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1120 PM PDT Tue Aug 10 2021

CAC065-110630-
/O.CAN.KPSR.FF.W.0140.000000T0000Z-210811T1100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
1120 PM PDT Tue Aug 10 2021

...FLASH FLOOD WARNING IS CANCELLED FOR RIVERSIDE 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 3385 11513 3380 11508 3370 11506 3359 11520
      3355 11537 3365 11548 3378 11544 3382 11539
      3386 11530 3385 11521

$$

Hirsch

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 10, 6:30 PM PDTSevere Thunderstorm WarningPSRRiverside45 min
Aug 10, 7:15 PM PDTDust Storm WarningPSRImperial, Riverside, San Bernardino60 min
Aug 10, 7:26 PM PDTSevere Thunderstorm WarningPSRImperial, Riverside49 min
Aug 10, 7:33 PM PDTFlash Flood Warning Considerable damage threatPSRImperial, Riverside4 hr
Aug 10, 8:18 PM PDTSevere Thunderstorm WarningPSRImperial, Riverside57 min
Aug 10, 8:38 PM PDTDust Storm WarningPSRImperial, Riverside52 min
Aug 10, 9:08 PM PDTFlash Flood Warning Considerable damage threatPSRImperial, Riverside6 hr
Aug 10, 9:42 PM PDTDust Storm WarningPSRImperial93 min
Aug 10, 11:16 PM PDTSpecial Weather StatementPSRImperial74 min
Aug 11, 2:01 PM PDTDust Storm AdvisoryPSRImperial59 min

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.