Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 92, NWS Phoenix, AZ

July 25, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 25, 2021, 4:18 PM PDT for Riverside County, California. It was in force for 4 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 25, 2021, 4:18 PM PDT (23:18 UTC)
Expired: Jul 25, 2021, 8:30 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 Santa Ana Mts radar (KSOX), 140 km from the middle of the area, began a volume at 23:20 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.

What was reported inside it

Time	Report	Where	Remark
Jul 25, 4:24 PM PDT	FLASH FLOOD	3 Nne Jtnp-Keys View, CA	KEYS VIEW ROAD CLOSED DUE TO FLOODING WITH 8 INCHES OF WATER FLOWING OVER ROADWAY.
Jul 25, 4:24 PM PDT	FLASH FLOOD	3 Nne Jtnp-Keys View, CA	* UPDATED * JOSHUA TREE NP-LOST HORSE ROAD/GEOLOGY TOUR ROAD/KEYS VIEW ROAD. LOST HORSE ROAD AND GEOLOGY TOUR ROAD ARE CLOSED DUE TO FLOODING. KEYS VIEW ROAD CLOSED DUE TO FLOODING WITH 8 INCHES OF WATER FLOWING OVER ROADWAY.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 11.3 hours before the alert went out and 163 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: 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.

136 
WGUS55 KPSR 252318
FFWPSR
CAC065-260330-
/O.NEW.KPSR.FF.W.0092.210725T2318Z-210726T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
418 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 830 PM PDT.

* At 418 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area which includes Quail Wash. 
  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...
  Key View.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3391 11607 3386 11613 3392 11620 3392 11624
      3396 11623 3402 11620 3403 11617 3403 11608
      3401 11605 3399 11602 3396 11604

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

$$

MS

2 follow-up statements

821 
WGUS75 KPSR 252346
FFSPSR

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

CAC065-260330-
/O.CON.KPSR.FF.W.0092.000000T0000Z-210726T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
446 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 446 PM PDT, local law enforcement reported Keys View Road has 
been closed down due to flooding.  One wash was flowing over the 
roadway with close to one foot of water.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Law enforcement reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Key View.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3391 11607 3386 11613 3392 11620 3392 11624
      3396 11623 3402 11620 3403 11617 3403 11608
      3401 11605 3399 11602 3396 11604

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

MS

733 
WGUS75 KPSR 260326
FFSPSR

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

CAC065-260336-
/O.EXP.KPSR.FF.W.0092.000000T0000Z-210726T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
826 PM PDT Sun Jul 25 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 830 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 3391 11607 3386 11613 3392 11620 3392 11624
      3396 11623 3402 11620 3403 11617 3403 11608
      3401 11605 3399 11602 3396 11604

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 11:59 AM PDT	Special Weather Statement	PSR	Riverside	31 min
Jul 25, 12:14 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	4 hr
Jul 25, 12:43 PM PDT	Special Weather Statement	PSR	Riverside	32 min
Jul 25, 1:12 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	4 hr
Jul 25, 1:24 PM PDT	Special Weather Statement	PSR	Riverside	51 min
Jul 25, 2:15 PM PDT	Special Weather Statement	PSR	Riverside	45 min
Jul 25, 2:34 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	7 hr
Jul 25, 2:38 PM PDT	Special Weather Statement	PSR	Riverside	37 min
Jul 25, 3:14 PM PDT	Special Weather Statement	PSR	Riverside	31 min
Jul 25, 3:20 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	5 hr
Jul 25, 3:41 PM PDT	Special Weather Statement	PSR	Riverside	34 min
Jul 25, 4:01 PM PDT	Severe Thunderstorm Warning	PSR	Riverside, San Bernardino	29 min

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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.