Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 236, NWS Phoenix, AZ

August 31, 2021Imperial County, Riverside County, California

NWS Phoenix, AZ issued this flash flood warning at Aug 31, 2021, 5:12 PM PDT for Imperial County, Riverside County, California. It was in force for 6 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
Aug 31, 2021, 5:12 PM PDT (00:12 UTC)
Expired
Aug 31, 2021, 11:15 PM PDT
In force
6 hr
Issued by
NWS Phoenix, AZ
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Imperial County, CA, Riverside County, CA

The radar

The San Diego radar (KNKX), 114 km from the middle of the area, began a volume at 00:13 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

TimeReportWhereRemark
Aug 31, 6:54 PM PDTFLASH FLOOD10 Sse Winona, CA***DELAYED REPORT*** WATER AND DEBRIS ACROSS SR 86 AT WILLOW WASH MAKING THE ROAD IMPASSABLE.

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, 0.2 hours before the alert went out and 131 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-pSkew-T log-p diagram, San Diego, CA at 00:00Z on 2021-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 00:00Z on 2021-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -77 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
853 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-77 m²/s²
0-3 km storm-relative helicity
-65 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

531 
WGUS55 KPSR 010012
FFWPSR
CAC025-065-010615-
/O.NEW.KPSR.FF.W.0236.210901T0012Z-210901T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
512 PM PDT Tue Aug 31 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Western Imperial County in southeastern California...
  Riverside County in southern California...

* Until 1115 PM PDT Tuesday.

* At 512 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain near Highway 86 along the Salton Sea. 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...
  El Centro, Brawley, Imperial, Plaster City, Salton City, Ocotillo, 
  Westmorland, El Centro Naval Airfield, Salton Sea Beach, Desert 
  Shores, Calipatria, Dixieland, Seeley, Winona, Alamorio, Coyote 
  Wells, Wiest, Heber and Coolidge Springs.

This includes the following highways...
	CA Route 86 between mile markers 10 and 19.
	CA Route 98 between mile markers 1 and 5.
	CA Interstate 8 between mile markers 11 and 20.
	CA Route 78 near mile marker 1...and
	between mile markers 10 and 18.
	CA Route 111 between mile markers 10 and 19.

This includes the following streams and drainages...
  Carrizo Wash, Coral Wash, Salton Sea, Alamo River, Tarantula Wash, 
  South Fork Palm Wash, Wonderstone Wash, Fish Creek Wash, New 
  River, Myer Creek, Palm Canyon Wash, Gert Wash, Salt Creek Slough, 
  Tule Wash and San Felipe Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3343 11603 3345 11604 3333 11578 3327 11570
      3315 11545 3294 11537 3274 11551 3267 11584
      3273 11602 3288 11607 3302 11607 3343 11607

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

$$

Hirsch
2 follow-up statements
178 
WGUS75 KPSR 010219
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
719 PM PDT Tue Aug 31 2021

CAC025-065-010615-
/O.CON.KPSR.FF.W.0236.000000T0000Z-210901T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-Riverside CA-
719 PM PDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1115 PM PDT THIS 
EVENING FOR WESTERN IMPERIAL AND RIVERSIDE COUNTIES...

At 719 PM PDT, Doppler radar indicated thunderstorms producing heavy 
rain in Imperial Valley. 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...
  El Centro, Brawley, Imperial, Plaster City, Salton City, Ocotillo, 
  Westmorland, El Centro Naval Airfield, Salton Sea Beach, Desert 
  Shores, Calipatria, Dixieland, Seeley, Winona, Alamorio, Coyote 
  Wells, Wiest, Heber and Coolidge Springs.

This includes the following highways...
	CA Route 86 between mile markers 10 and 19.
	CA Route 98 near mile marker 1...and
	between mile markers 12 and 13...and
	between mile markers 2 and 5.
	CA Interstate 8 between mile markers 11 and 20.
	CA Route 78 near mile marker 1...and
	between mile markers 10 and 18.
	CA Route 111 between mile markers 10 and 19.

This includes the following streams and drainages...
  Carrizo Wash, Coral Wash, Salton Sea, Alamo River, Tarantula Wash, 
  South Fork Palm Wash, Wonderstone Wash, Fish Creek Wash, New 
  River, Myer Creek, Palm Canyon Wash, Gert Wash, Salt Creek Slough, 
  Tule Wash and San Felipe Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3343 11603 3345 11604 3333 11578 3327 11570
      3315 11545 3294 11537 3274 11551 3267 11584
      3273 11602 3288 11607 3302 11607 3343 11607

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

$$

Hirsch
805 
WGUS75 KPSR 010610
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1110 PM PDT Tue Aug 31 2021

CAC025-065-010620-
/O.EXP.KPSR.FF.W.0236.000000T0000Z-210901T0615Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-Riverside CA-
1110 PM PDT Tue Aug 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1115 PM PDT THIS EVENING FOR 
WESTERN IMPERIAL AND RIVERSIDE 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.

A Flash Flood Watch remains in effect until 200 AM PDT for portions 
of southwest Arizona and California.

LAT...LON 3343 11603 3345 11604 3333 11578 3327 11570
      3315 11545 3294 11537 3274 11551 3267 11584
      3273 11602 3288 11607 3302 11607 3343 11607

$$

CK

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 31, 5:58 PM PDTFlash Flood Warning Considerable damage threatPSRImperial, Riverside8 hr
Aug 31, 7:41 PM PDTFlash Flood Warning Considerable damage threatPSRImperial8 hr

Nearby

Flash Flood Warnings in California, 2021Every 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.