Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 247, NWS Phoenix, AZ

September 10, 2021Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Sep 10, 2021, 4:22 PM PDT for Imperial County, California. It was in force for 5 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 10, 2021, 4:22 PM PDT (23:22 UTC)
Expired: Sep 10, 2021, 9:15 PM PDT
In force: 5 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Imperial County, CA

The radar

The San Diego radar (KNKX), 100 km from the middle of the area, began a volume at 23:22 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, 11.4 hours before the alert went out and 117 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: 4 J/kg
Mixed-layer CIN: -583 J/kg
Mixed-layer LCL: 1725 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 40 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

427 
WGUS55 KPSR 102322
FFWPSR
CAC025-110715-
/O.NEW.KPSR.FF.W.0247.210910T2322Z-210911T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
422 PM PDT Fri Sep 10 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  West Central Imperial County in southeastern California...

* Until 1215 AM PDT Saturday.

* At 422 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across far western Imperial County. Up to 1 inch of 
  rain has fallen. Additional rainfall amounts up to 1 inch are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly. Running water in Carrizo Wash and San Filipe 
  Creek may reach low water crossings along Highway 78.

  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 West Central Imperial County

This includes the following highways...
	CA Route 86 between mile markers 40 and 49.
	CA Route 78 near mile marker 1...and
	between mile markers 10 and 13...and
	between mile markers 2 and 6.

This includes the following streams and drainages...
  Carrizo Wash, Tarantula Wash, Fish Creek Wash, Gert Wash, Tule 
  Wash and San Felipe Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3321 11608 3319 11588 3310 11579 3305 11590
      3300 11589 3290 11591 3283 11593 3277 11610
      3307 11610 3307 11608

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

$$

Hirsch

1 follow-up statement

235 
WGUS75 KPSR 110415
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
915 PM PDT Fri Sep 10 2021

CAC025-110425-
/O.CAN.KPSR.FF.W.0247.000000T0000Z-210911T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
915 PM PDT Fri Sep 10 2021

...FLASH FLOOD WARNING IS CANCELLED FOR WEST CENTRAL IMPERIAL 
COUNTY...

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 3321 11608 3319 11588 3310 11579 3305 11590
      3300 11589 3290 11591 3283 11593 3277 11610
      3307 11610 3307 11608

$$

Hirsch

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 9, 5:14 PM PDT	Special Weather Statement	PSR	Riverside	31 min
Sep 9, 5:47 PM PDT	Flash Flood Warning Considerable damage threat	PSR	Riverside	3 hr
Sep 9, 5:52 PM PDT	Special Weather Statement	PSR	Riverside	23 min
Sep 10, 2:19 AM PDT	Excessive Heat Warning	PSR	Imperial, Riverside, San Bernardino	4 days
Sep 10, 4:03 PM PDT	Severe Thunderstorm Warning	PSR	Imperial	42 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.