Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 6, NWS San Diego, CA

July 26, 2021Riverside County, California

NWS San Diego, CA issued this flash flood warning at Jul 26, 2021, 3:29 AM PDT for Riverside County, California. It was in force for 3 hr. 8 reports 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 26, 2021, 3:29 AM PDT (10:29 UTC)
Expired
Jul 26, 2021, 6:30 AM PDT
In force
3 hr
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Riverside County, CA

The radar

The San Diego radar (KNKX), 105 km from the middle of the area, began a volume at 10:33 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.

What was reported inside it

TimeReportWhereRemark
Jul 26, 3:30 AM PDTFLASH FLOOD3 E Mecca, CADELAYED REPORT. RADAR ESTIMATED 2 TO 2.5 INCHES OF RAINFALL AT THE MOUTH OF BOX CANYON WHICH CAUSED FLASH FLOODING AT THE ENTRANCE OF BOX CANYON ROAD AND ALONG PAINTED CANYON ROAD. THERE WERE A COUPLE VEHICLES INVOLVED WITH THE FLOODING WHICH CAUSED A ROAD CLO
Jul 26, 4:06 AM PDTFLASH FLOOD4 E Mecca, CAONE VEHICLE SWEPT OFF THE ROADWAY ON BOX CANYON ROAD WITH 10 TO 12 OTHER VEHICLES POTENTIALLY STRANDED.
Jul 26, 4:30 AM PDTFLOOD1 Ese Thousand Palms, CADESERT SUN PHOTO OF MUD AND WATER COVERING VISTA DEL SOL AND RAMON ROAD IN THOUSAND PALMS. THIS AREA RECEIVED HEAVY RAIN 3 TO 6 AM. NEARBY CATHEDRAL CITY SITE REPORTED 0.52 INCHES IN 1 HOUR.
Jul 26, 5:00 AM PDTHEAVY RAIN 0.693 Sse Palm Springs, CACATHEDRAL CANYON RAWS HAD 0.42 RAINFALL IN 1 HOUR AND 0.69 INCHES TOTAL.
Jul 26, 5:00 AM PDTHEAVY RAIN 1.611 E Indio, CARAIN GAUGE (CIMIS) REPORTED 2 HOURS OF 0.70 PER HOUR AND TOTAL OF 1.61 INCHES. RADAR KYUX ESTIMATED AROUND 2 INCHES IN THIS AREA.
Jul 26, 5:11 AM PDTFLASH FLOOD7 Ssw Palm Desert, CACALTRANS REPORTS BOULDERS IN THE ROADWAY NEAR VISTA POINT ON SR 74.
Jul 26, 5:30 AM PDTFLASH FLOOD1 E Bermuda Dunes, CADAMAGE AND WASHED OUT SECTION OF CONCRETE SIDEWALK AS EMBANKMENT GAVE WAY TO FLOODING ALONG COUNTRY CLUB DRIVE AND AVENUE 42. ALSO WATER COVERED ROADWAY ON JEFFERSON STREET. PHOTOS SHARED BY EMERGENCY MANAGEMENT. RAIN OF 0.70 PER HOUR OBSERVED AND UP TO 1.60 I
Jul 26, 6:07 AM PDTFLASH FLOOD1 Ene Bermuda Dunes, CAFLOODING ON VARNER ROAD.

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, 10.5 hours before the alert went out and 124 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 2021-07-26Temperature 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 2021-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 36 square meters per square second.1939Sfc1 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
1166 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
36 m²/s²
0-3 km storm-relative helicity
90 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

513 
WGUS56 KSGX 261029
FFWSGX
CAC065-261330-
/O.NEW.KSGX.FF.W.0006.210726T1029Z-210726T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
329 AM PDT Mon Jul 26 2021

The National Weather Service in San Diego has issued a

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

* Until 630 AM PDT.

* At 329 AM PDT, Doppler radar and satellite imagery indicated 
  numerous thunderstorms developing in the Valley. Heavy rain has 
  been reported at Thermal. Flash flooding is likely to develop.

  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...
  Indio, southeastern Palm Springs, Coachella, Mt San Jacinto State 
  Park, Cathedral City, Palm Desert, Rancho Mirage, Thermal, Hwy 74 
  Between Anza And Palm Desert, La Quinta, Mecca, Indian Wells, 
  Bermuda Dunes, Thousand Palms, Santa Rosa Mountain and Sky Valley.

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.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3392 11620 3374 11595 3351 11595 3351 11607
      3343 11603 3343 11620 3350 11633 3350 11631
      3350 11627 3351 11627 3360 11633 3359 11642
      3370 11648 3369 11649 3368 11649 3366 11651
      3363 11651 3383 11662

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

$$

10
1 follow-up statement
236 
WGUS76 KSGX 261202
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
502 AM PDT Mon Jul 26 2021

CAC065-261330-
/O.CON.KSGX.FF.W.0006.000000T0000Z-210726T1330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-
502 AM PDT Mon Jul 26 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 AM PDT THIS 
MORNING FOR RIVERSIDE COUNTY...

At 502 AM PDT, Doppler radar indicated heavy rainfall continuing 
across the Warning area. Flash flooding has been observed east of 
Mecca where numerous vehicles were stranded. Additional rainfall 
amounts of up to 1 inch are expected.

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...
  Indio, southeastern Palm Springs, Coachella, Mt San Jacinto State 
  Park, Cathedral City, Palm Desert, Rancho Mirage, Thermal, Hwy 74 
  Between Anza And Palm Desert, La Quinta, Mecca, Indian Wells, 
  Bermuda Dunes, Thousand Palms, Santa Rosa Mountain and Sky Valley.

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.

Please report observed flooding to local emergency services or law 
enforcement and request they pass this information to the National 
Weather Service when you can do so safely.

&&

LAT...LON 3392 11620 3374 11595 3351 11595 3351 11607
      3343 11603 3343 11620 3350 11633 3350 11631
      3350 11627 3351 11627 3360 11633 3359 11642
      3370 11648 3369 11649 3368 11649 3366 11651
      3363 11651 3383 11662

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

$$

MM

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 6:53 PM PDTFlash Flood WatchSGXRiverside, San Bernardino, San Diego23 hr
Jul 26, 2:11 AM PDTAreal Flood AdvisorySGXSan Bernardino2 hr
Jul 26, 4:53 AM PDTAreal Flood AdvisorySGXRiverside, San Diego3 hr
Jul 26, 6:32 AM PDTAreal Flood AdvisorySGXRiverside2 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.