Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 17, NWS San Diego, CA

September 24, 2021San Diego County, California

NWS San Diego, CA issued this flash flood warning at Sep 24, 2021, 12:21 PM PDT for San Diego County, California. It was in force for 56 min. 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 24, 2021, 12:21 PM PDT (19:21 UTC)
Expired
Sep 24, 2021, 1:17 PM PDT
In force
56 min
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County San Diego County, CA

The radar

The San Diego radar (KNKX), 39 km from the middle of the area, began a volume at 19:23 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, 7.4 hours before the alert went out and 52 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 2021-09-24Temperature 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 2021-09-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -36 square meters per square second.1939587897Sfc1 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
1990 m above ground
0-6 km bulk shear
4 kt
0-1 km storm-relative helicity
-36 m²/s²
0-3 km storm-relative helicity
15 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

308 
WGUS56 KSGX 241921
FFWSGX
CAC073-242230-
/O.NEW.KSGX.FF.W.0017.210924T1921Z-210924T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
1221 PM PDT Fri Sep 24 2021

The National Weather Service in San Diego has issued a

* Flash Flood Warning for...
  South Central San Diego County in southwestern California...

* Until 330 PM PDT.

* At 1221 PM PDT, Doppler radar indicated thunderstorms producing 
  heavy rain across 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...
  Alpine, I-8 Between Pine Valley And Alpine, Descanso, Pine Valley, 
  Guatay, Viejas Indian Reservation, Japatul Valley, Skye Valley, 
  Boulder Creek and Captain Grande Indian Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3272 11674 3294 11675 3292 11653 3273 11648

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

$$

Maxwell
1 follow-up statement
709 
WGUS76 KSGX 242017
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
117 PM PDT Fri Sep 24 2021

CAC073-242027-
/O.CAN.KSGX.FF.W.0017.000000T0000Z-210924T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Diego CA-
117 PM PDT Fri Sep 24 2021

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTH CENTRAL SAN DIEGO 
COUNTY...

The heavy rain has ended in south-central San Diego County. Flooding 
is no longer expected to pose a threat.

A Flash Flood Watch remains in effect until 700 PM PDT for a portion 
of southwest California due to the risk of more thunderstorm 
development this afternoon.

LAT...LON 3272 11674 3294 11675 3292 11653 3273 11648

$$

Maxwell

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 24, 8:56 AM PDTFlash Flood WatchSGXRiverside, San Diego10 hr
Sep 24, 11:08 AM PDTBeach Hazards StatementSGXOrange, San Diego8 hr
Sep 24, 12:13 PM PDTSevere Thunderstorm WarningSGXSan Diego31 min
Sep 24, 1:24 PM PDTSevere Thunderstorm WarningSGXSan Diego51 min
Sep 24, 1:28 PM PDTFlash Flood Warning Considerable damage threatSGXSan Diego2 hr
Sep 24, 2:09 PM PDTFlash Flood Warning Considerable damage threatSGXSan Diego3 hr
Sep 24, 2:41 PM PDTSevere Thunderstorm WarningSGXSan Diego64 min
Sep 24, 2:59 PM PDTSpecial Weather StatementSGXSan Diego61 min
Sep 24, 3:14 PM PDTSpecial Marine WarningSGX91 min
Sep 24, 3:20 PM PDTSevere Thunderstorm WarningSGXSan Diego55 min
Sep 24, 3:47 PM PDTSpecial Weather StatementSGXOrange58 min
Sep 24, 3:56 PM PDTSpecial Marine WarningSGX94 min
Sep 24, 4:40 PM PDTSpecial Marine WarningSGX65 min

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.