Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 103, NWS Phoenix, AZ

July 28, 2021Riverside County, San Bernardino County, California

NWS Phoenix, AZ issued this flash flood warning at Jul 28, 2021, 1:20 PM PDT for Riverside County, San Bernardino County, California. It was in force for 3 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 28, 2021, 1:20 PM PDT (20:20 UTC)
Expired: Jul 28, 2021, 4:00 PM PDT
In force: 3 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Riverside County, CA, San Bernardino County, CA

The radar

The Santa Ana Mts radar (KSOX), 140 km from the middle of the area, began a volume at 20:23 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 28, 1:34 PM PDT	FLASH FLOOD	6 Nne Jtnp-Lost Horse R, CA	* DELAYED REPORT * SOME OF THE SHOULDERS ALONG INDIAN COVE RD. WERE WASHED OUT AND A FEW INCHES OF FAST MOVING WATER OVER THE ROADWAY. TIME ESTIMATED FROM RADAR.

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, 8.3 hours before the alert went out and 171 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: 1533 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 55 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

294 
WGUS55 KPSR 282020
FFWPSR
CAC065-071-282300-
/O.NEW.KPSR.FF.W.0103.210728T2020Z-210728T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
120 PM PDT Wed Jul 28 2021

The National Weather Service in Phoenix has issued a

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

* Until 400 PM PDT.

* At 120 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain in Joshua Tree National Park. Between 0.5 and 1.5 
  inches of rain have fallen. Additional rainfall amounts of 0.5 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 and San Bernardino Counties

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 3408 11630 3408 11628 3408 11626 3412 11626
      3412 11605 3411 11605 3411 11604 3408 11604
      3408 11602 3402 11601 3396 11612 3399 11624

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

$$

SDB

2 follow-up statements

285 
WGUS75 KPSR 282244 RRA
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
344 PM PDT Wed Jul 28 2021

CAC065-071-282300-
/O.CON.KPSR.FF.W.0103.000000T0000Z-210728T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
344 PM PDT Wed Jul 28 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM PDT THIS 
AFTERNOON FOR RIVERSIDE AND SAN BERNARDINO COUNTIES...

At 344 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain in Joshua Tree National Park. 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. This
         includes Quail Wash and Queen Valley Wash.

Some locations that will experience flash flooding include...
  mainly rural areas of Riverside and San Bernardino Counties

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 3408 11630 3408 11628 3408 11626 3412 11626
      3412 11605 3411 11605 3411 11604 3408 11604
      3408 11602 3402 11601 3396 11612 3399 11624

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

$$

Iniguez

213 
WGUS75 KPSR 282256
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
356 PM PDT Wed Jul 28 2021

CAC065-071-282306-
/O.EXP.KPSR.FF.W.0103.000000T0000Z-210728T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
356 PM PDT Wed Jul 28 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 4 PM PDT THIS AFTERNOON FOR 
RIVERSIDE AND SAN BERNARDINO COUNTIES...

The heavy rain has ended across the far northwest portions of Joshua 
Tree National Park. Flooding is no longer expected to pose a threat. 
Please continue to heed remaining road closures.

LAT...LON 3408 11630 3408 11628 3408 11626 3412 11626
      3412 11605 3411 11605 3411 11604 3408 11604
      3408 11602 3402 11601 3396 11612 3399 11624

$$

Iniguez

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 28, 11:49 AM PDT	Areal Flood Advisory	PSR	Riverside	3 hr
Jul 28, 1:00 PM PDT	Areal Flood Advisory	PSR	Riverside, San Bernardino	20 min
Jul 28, 2:00 PM PDT	Areal Flood Advisory	PSR	Riverside	42 min
Jul 28, 2:42 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	2 hr
Jul 28, 4:07 PM PDT	Areal Flood Advisory	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.