Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 129, NWS Phoenix, AZ

August 9, 2021Riverside County, San Bernardino County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 9, 2021, 2:38 PM PDT for Riverside County, San Bernardino County, California. It was in force for 3 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: Aug 9, 2021, 2:38 PM PDT (21:38 UTC)
Expired: Aug 9, 2021, 6:01 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), 148 km from the middle of the area, began a volume at 21:39 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 174 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: 1565 m above ground
0-6 km bulk shear: 6 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 14 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

806 
WGUS55 KPSR 092138
FFWPSR
CAC065-071-100145-
/O.NEW.KPSR.FF.W.0129.210809T2138Z-210810T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
238 PM PDT Mon Aug 9 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 645 PM PDT.

* At 238 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,
           roads and low lying areas.

* Some locations that will experience flash flooding include...
  northwest portions of Joshua Tree National Park.

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 3403 11617 3407 11617 3412 11617 3412 11605
      3411 11605 3411 11604 3408 11604 3408 11600
      3403 11600 3404 11596 3403 11596 3402 11596
      3400 11598 3399 11603 3398 11608 3399 11612
      3401 11615

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

$$

AJ

4 follow-up statements

962 
WGUS75 KPSR 092209
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
309 PM PDT Mon Aug 9 2021

CAC065-071-100145-
/O.CON.KPSR.FF.W.0129.000000T0000Z-210810T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
309 PM PDT Mon Aug 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 645 PM PDT THIS 
EVENING FOR RIVERSIDE AND SAN BERNARDINO COUNTIES...

At 309 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. Flash flooding is likely ongoing.

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

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         roads, and low lying areas.

Some locations that will experience flash flooding include...
  northwest portions of Joshua Tree National Park including the 
  north entrance to the Park near 29 Palms.

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 3403 11617 3407 11617 3412 11617 3412 11605
      3411 11605 3411 11604 3408 11604 3408 11600
      3403 11600 3404 11596 3403 11596 3402 11596
      3400 11598 3399 11603 3398 11608 3399 11612
      3401 11615

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

$$

AJ

605 
WGUS75 KPSR 092249
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
349 PM PDT Mon Aug 9 2021

CAC065-071-100145-
/O.CON.KPSR.FF.W.0129.000000T0000Z-210810T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
349 PM PDT Mon Aug 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 645 PM PDT THIS 
EVENING FOR RIVERSIDE AND SAN BERNARDINO COUNTIES...

At 349 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. Flash flooding is likely ongoing.

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

SOURCE...Radar.

IMPACT...Life threatening flash flooding of creeks and streams,
         roadways, and low lying areas.

Some locations that will experience flash flooding include...
  northwest portions of Joshua Tree National Park including the 
  north entrance to the Park near 29 Palms.

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 normally dry washes which can become killers in 
heavy rains. Campers and hikers should avoid streams or creeks.

&&

LAT...LON 3403 11617 3407 11617 3412 11617 3412 11605
      3411 11605 3411 11604 3408 11604 3408 11600
      3403 11600 3404 11596 3403 11596 3402 11596
      3400 11598 3399 11603 3398 11608 3399 11612
      3401 11615

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

$$

AJ

853 
WGUS75 KPSR 100012
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
512 PM PDT Mon Aug 9 2021

CAC065-071-100145-
/O.CON.KPSR.FF.W.0129.000000T0000Z-210810T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
512 PM PDT Mon Aug 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 645 PM PDT THIS 
EVENING FOR RIVERSIDE AND SAN BERNARDINO COUNTIES...

At 512 PM PDT, Park staff reported flooding near the north entrance 
to the Park and in the Indian Cove area. Other locations in and near 
those areas likely have ongoing flooding.

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

SOURCE...Public reported.

IMPACT...Life threatening flash flooding of creeks and streams,
         roadways and low lying areas.

Some locations that will experience flash flooding include...
  northwest portions of Joshua Tree National Park including the 
  north entrance to the Park near 29 Palms.

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 normally dry washes which can become killers in
heavy rains. Campers and hikers should avoid flooded washes and 
roadways.

&&

LAT...LON 3403 11617 3407 11617 3412 11617 3412 11605
      3411 11605 3411 11604 3408 11604 3408 11600
      3403 11600 3404 11596 3403 11596 3402 11596
      3400 11598 3399 11603 3398 11608 3399 11612
      3401 11615

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

$$

AJ

852 
WGUS75 KPSR 100101
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
601 PM PDT Mon Aug 9 2021

CAC065-071-100111-
/O.CAN.KPSR.FF.W.0129.000000T0000Z-210810T0145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
601 PM PDT Mon Aug 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR RIVERSIDE AND SAN BERNARDINO 
COUNTIES...

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 3403 11617 3407 11617 3412 11617 3412 11605
      3411 11605 3411 11604 3408 11604 3408 11600
      3403 11600 3404 11596 3403 11596 3402 11596
      3400 11598 3399 11603 3398 11608 3399 11612
      3401 11615

$$

AJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 9, 1:44 PM PDT	Areal Flood Advisory	PSR	Riverside, San Bernardino	3 hr
Aug 9, 3:26 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.