Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 14, NWS San Diego, CA

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

NWS San Diego, CA issued this flash flood warning at Sep 9, 2021, 3:29 PM PDT for Riverside County, San Bernardino County, California. It was in force for 2 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: Sep 9, 2021, 3:29 PM PDT (22:29 UTC)
Expired: Sep 9, 2021, 5:30 PM PDT
In force: 2 hr
Issued by: NWS San Diego, CA
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), 54 km from the middle of the area, began a volume at 22:33 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, 10.5 hours before the alert went out and 138 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: 15 J/kg
Mixed-layer CIN: -787 J/kg
Mixed-layer LCL: 1710 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 112 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

781 
WGUS56 KSGX 092229
FFWSGX
CAC065-071-100030-
/O.NEW.KSGX.FF.W.0014.210909T2229Z-210910T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
329 PM PDT Thu Sep 9 2021

The National Weather Service in San Diego has issued a

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

* Until 530 PM PDT.

* At 329 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.25 and 0.5 inches of 
  rain have fallen. Additional rainfall amounts of 0.25 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...
  Moreno Valley, Redlands, Yucaipa, Highland, western Beaumont, 
  Mentone, Calimesa and Cherry Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3406 11721 3411 11717 3411 11705 3406 11703
      3399 11697 3394 11709 3395 11713

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

$$

SS

2 follow-up statements

894 
WGUS76 KSGX 092342
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
442 PM PDT Thu Sep 9 2021

CAC065-071-100030-
/O.CON.KSGX.FF.W.0014.000000T0000Z-210910T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
442 PM PDT Thu Sep 9 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM PDT THIS 
AFTERNOON FOR RIVERSIDE AND SAN BERNARDINO COUNTIES...

At 442 PM PDT, Doppler radar indicated new thunderstorms producing 
heavy rain moving into the warned area. Additional rainfall amounts 
of 0.25 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...
  Moreno Valley, Redlands, Yucaipa, Highland, western Beaumont, 
  Mentone,  Calimesa and Cherry Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3406 11721 3411 11717 3411 11705 3406 11703
      3399 11697 3394 11709 3395 11713

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

$$

SS

926 
WGUS76 KSGX 100026
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
526 PM PDT Thu Sep 9 2021

CAC065-071-100036-
/O.EXP.KSGX.FF.W.0014.000000T0000Z-210910T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Bernardino CA-
526 PM PDT Thu Sep 9 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 530 PM PDT THIS AFTERNOON FOR 
RIVERSIDE AND SAN BERNARDINO COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures and avoid 
flooded areas.

LAT...LON 3406 11721 3411 11717 3411 11705 3406 11703
      3399 11697 3394 11709 3395 11713

$$

SS

The office that day

Everything else NWS San Diego, CA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 9, 12:40 PM PDT	Special Weather Statement	SGX		50 min
Sep 9, 1:05 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	40 min
Sep 9, 1:19 PM PDT	Severe Thunderstorm Warning Considerable damage threat	SGX	San Bernardino	22 min
Sep 9, 2:12 PM PDT	Areal Flood Advisory	SGX	San Diego	3 hr
Sep 9, 2:34 PM PDT	Flash Flood Warning Considerable damage threat	SGX	San Bernardino	3 hr
Sep 9, 2:54 PM PDT	Severe Thunderstorm Warning	SGX	San Bernardino	66 min
Sep 9, 3:10 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	50 min
Sep 9, 3:25 PM PDT	Special Weather Statement	SGX		50 min
Sep 9, 3:46 PM PDT	Areal Flood Advisory	SGX	Riverside	3 hr
Sep 9, 4:33 PM PDT	Flash Flood Warning Considerable damage threat	SGX	Riverside	88 min
Sep 9, 4:35 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Bernardino	55 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.