Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 10, NWS San Diego, CA

August 29, 2021Riverside County, San Diego County, California

NWS San Diego, CA issued this flash flood warning at Aug 29, 2021, 1:18 PM PDT for Riverside County, San Diego 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 29, 2021, 1:18 PM PDT (20:18 UTC)
Expired
Aug 29, 2021, 4:30 PM PDT
In force
3 hr
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Riverside County, CA, San Diego County, CA

The radar

The San Diego radar (KNKX), 55 km from the middle of the area, began a volume at 20:20 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, 8.3 hours before the alert went out and 74 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 12:00Z on 2021-08-29Temperature 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 12:00Z on 2021-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -9 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
2595 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
-9 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

913 
WGUS56 KSGX 292018
FFWSGX
CAC065-073-292330-
/O.NEW.KSGX.FF.W.0010.210829T2018Z-210829T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
118 PM PDT Sun Aug 29 2021

The National Weather Service in San Diego has issued a

* Flash Flood Warning for...
  Riverside County in southern California...
  North Central San Diego County in southwestern California...

* Until 430 PM PDT.

* At 118 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.75 and 1.5 inches of 
  rain have fallen. The expected rainfall rate is 0.5 to 0.75 inches 
  in 1 hour. Additional rainfall amounts of 0.5 to 1 inch are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly. Temecula and Bear Creeks have received the most 
  rainfall.

  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...
  Hwy 79 Between Warner Springs And Oak Grove, Hwy 79 Between Oak 
  Grove And Aguanga, S7 - East Grade Rd, Palomar Mountain, Lake 
  Henshaw, Warner Springs, Hwy 79 Between Santa Ysabel And Warner 
  Springs, Aguanga, Oak Grove, La Jolla Indian Reservation and Los 
  Coyotes Indian Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3348 11690 3346 11675 3345 11674 3344 11670
      3340 11667 3336 11662 3331 11660 3328 11659
      3327 11661 3324 11677 3324 11679 3327 11684
      3329 11687 3333 11688 3336 11690 3342 11691

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.5-0.75 INCHES IN 1 HOUR

$$

Tardy
1 follow-up statement
425 
WGUS76 KSGX 292326
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
426 PM PDT Sun Aug 29 2021

CAC065-073-292336-
/O.EXP.KSGX.FF.W.0010.000000T0000Z-210829T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Riverside CA-San Diego CA-
426 PM PDT Sun Aug 29 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 430 PM PDT THIS AFTERNOON FOR 
RIVERSIDE AND NORTH CENTRAL SAN DIEGO COUNTIES...

Flood waters have receded in Temecula Creek on the northeast side of 
Palomar Mountain. The heavy rain has ended. Flooding is no longer 
expected to pose a threat. Please continue to heed remaining road 
closures. Low lying areas may still have standing water.

LAT...LON 3348 11690 3346 11675 3345 11674 3344 11670
      3340 11667 3336 11662 3331 11660 3328 11659
      3327 11661 3324 11677 3324 11679 3327 11684
      3329 11687 3333 11688 3336 11690 3342 11691

$$

Tardy

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 29, 12:49 PM PDTAreal Flood AdvisorySGXRiverside3 hr
Aug 29, 12:54 PM PDTSpecial Weather StatementSGXSan Diego51 min
Aug 29, 2:35 PM PDTSpecial Weather StatementSGXSan Diego40 min
Aug 29, 3:51 PM PDTAreal Flood AdvisorySGXSan Diego114 min
Aug 29, 4:24 PM PDTAreal Flood AdvisorySGXSan Bernardino3 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.