Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 115, NWS Phoenix, AZ

July 30, 2021Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 30, 2021, 5:24 PM PDT for Riverside County, California. It was in force for 4 hr. 1 report 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 30, 2021, 5:24 PM PDT (00:24 UTC)
Expired: Jul 30, 2021, 9:30 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 San Diego radar (KNKX), 143 km from the middle of the area, began a volume at 00:25 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.

What was reported inside it

Time	Report	Where	Remark
Jul 30, 6:15 PM PDT	FLASH FLOOD	10 E Jtnp-Lost Horse Ra, CA	* DELAYED REPORT * SOCIAL MEDIA POST SHOWS SEVERAL INCHES OF WATER ACROSS ROADWAY IMPEDING TRAVEL ALONG PARK BLVD./PINTO BASIN RD. FROM JTNP NORTH ENTRANCE TO SOUTH ENTRANCE. SAME REPORT SAID THERE WAS HEAVY FLOODING WITH ROAD WASHED OUT IN MULTIPLE PARTS.

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 00:00Z, 0.4 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: 2564 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: -18 m²/s²
0-3 km storm-relative helicity: 33 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

396 
WGUS55 KPSR 310024
FFWPSR
CAC065-310430-
/O.NEW.KPSR.FF.W.0115.210731T0024Z-210731T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
524 PM PDT Fri Jul 30 2021

The National Weather Service in Phoenix has issued a

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

* Until 930 PM PDT.

* At 524 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 0.5 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...
  Chiriaco Summit and Cottonwood Visitor Center.

This includes the following highways...
	CA Interstate 10 between mile markers 74 and 83.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3389 11617 3401 11609 3403 11610 3403 11603
      3403 11599 3403 11598 3403 11595 3381 11574
      3365 11567 3355 11595 3374 11595 3374 11600
      3383 11613 3385 11613

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

$$

INS

2 follow-up statements

737 
WGUS75 KPSR 310137
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
637 PM PDT Fri Jul 30 2021

CAC065-310430-
/O.CON.KPSR.FF.W.0115.000000T0000Z-210731T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
637 PM PDT Fri Jul 30 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 930 PM PDT THIS 
EVENING FOR RIVERSIDE COUNTY...

At 637 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. Additional rainfall amounts up to 0.5 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...
  Chiriaco Summit and Cottonwood Visitor Center.

This includes the following highways...
	CA Interstate 10 between mile markers 74 and 83.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3389 11617 3401 11609 3403 11610 3403 11603
      3403 11599 3403 11598 3403 11595 3381 11574
      3365 11567 3355 11595 3374 11595 3374 11600
      3383 11613 3385 11613

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

$$

INS

092 
WGUS75 KPSR 310422
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
922 PM PDT Fri Jul 30 2021

CAC065-310432-
/O.EXP.KPSR.FF.W.0115.000000T0000Z-210731T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
922 PM PDT Fri Jul 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 930 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.

A Flash Flood Watch remains in effect until 500 AM PDT Saturday for 
portions of Arizona and California.

LAT...LON 3389 11617 3401 11609 3403 11610 3403 11603
      3403 11599 3403 11598 3403 11595 3381 11574
      3365 11567 3355 11595 3374 11595 3374 11600
      3383 11613 3385 11613

$$

INS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 5:04 PM PDT	Dust Storm Advisory	PSR	Imperial	41 min
Jul 30, 5:18 PM PDT	Special Weather Statement	PSR	Imperial	72 min
Jul 30, 5:20 PM PDT	Special Weather Statement	PSR	Riverside	70 min
Jul 30, 5:29 PM PDT	Severe Thunderstorm Warning	PSR	Imperial	46 min
Jul 30, 5:33 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial	4 hr
Jul 30, 5:39 PM PDT	Areal Flood Advisory	PSR	Imperial	3 hr
Jul 30, 5:52 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	4 hr
Jul 30, 5:59 PM PDT	Dust Storm Warning	PSR	Imperial	45 min
Jul 30, 6:06 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial	4 hr
Jul 30, 6:11 PM PDT	Severe Thunderstorm Warning	PSR	Riverside	79 min
Jul 30, 6:31 PM PDT	Special Weather Statement	PSR	Imperial	74 min
Jul 30, 6:49 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Imperial, Riverside	4 hr
Jul 31, 2:32 PM PDT	Special Weather Statement	PSR	Riverside	28 min
Jul 31, 3:47 PM PDT	Special Weather Statement	PSR	Riverside	28 min
Jul 31, 4:48 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.