Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 21, NWS San Diego, CA

December 14, 2021Orange County, California

NWS San Diego, CA issued this flash flood warning at Dec 14, 2021, 10:36 AM PST for Orange County, California. It was in force for 3 hr. 2 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: Dec 14, 2021, 10:36 AM PST (18:36 UTC)
Expired: Dec 14, 2021, 1:45 PM PST
In force: 3 hr
Issued by: NWS San Diego, CA
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Orange County, CA

What was reported inside it

Time	Report	Where	Remark
Dec 14, 10:40 AM PST	HEAVY RAIN 2.13	2 Nnw Aliso Viejo, CA	HEAVY RAINFALL IN LAST TWO HOURS HAS BEEN FALLING IN ALISO VIEJO AREA AVERAGING ABOUT 0.6 PER HOUR. IN THE LAST 30 MINUTES, RAINFALL TEMPO HAS REALLY PICKED AND I NOW ESTIMATING A RATE CLOSER TO AN INCH PER HOUR. TOTAL INTERIM RAINFAILL TOTAL IS NOW 2 1/8 INCH
Dec 14, 11:13 AM PST	FLOOD	3 Nw Aliso Viejo, CA	REPORTS OF FLOODING ON BOTH HIGHWAY ON RAMPS OF SR133 AND LAGUNA CANYON RD OFF RAMP. RAIN RATES OF 0.40 TO 0.50 INCHES AND HOUR HAVE FALLEN OVER THE AREA WITH NEAR AN INCH OVER THE PAST 6 HOURS.

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 12:00Z, 6.6 hours before the alert went out and 108 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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 666 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 200 m²/s²
0-3 km storm-relative helicity: 172 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

262 
WGUS56 KSGX 141836
FFWSGX
CAC059-142145-
/O.NEW.KSGX.FF.W.0021.211214T1836Z-211214T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Diego CA
1036 AM PST Tue Dec 14 2021

The National Weather Service in San Diego has issued a

* Flash Flood Warning for...
  Central Orange County in southwestern California...

* Until 145 PM PST.

* At 1036 AM PST, Doppler radar and automated rain gauges indicated 
  heavy rain falling across the warned area. The expected rainfall 
  rate is 0.5 to 1 inch in 1 hour. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Radar and automated gauges.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Irvine, Tustin, Laguna Beach, Newport Beach, Aliso Viejo, Laguna 
  Woods, San Joaquin Hills, Newport Coast, Laguna Hills and Crystal 
  Cove State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3360 11791 3361 11790 3362 11789 3363 11788
      3363 11789 3372 11782 3359 11768 3354 11778
      3355 11782 3357 11784 3359 11788

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL RATE...0.5-1 INCH IN 1 HOUR

$$

Connolly

1 follow-up statement

757 
WGUS76 KSGX 142145
FFSSGX

Flash Flood Statement
National Weather Service San Diego CA
145 PM PST Tue Dec 14 2021

CAC059-142155-
/O.EXP.KSGX.FF.W.0021.000000T0000Z-211214T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Orange CA-
145 PM PST Tue Dec 14 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR CENTRAL ORANGE COUNTY...

The heavy rain has ended for now. Flooding is no longer expected to 
pose a threat. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 900 PM PST Tuesday for a 
portion of Southern California.

LAT...LON 3360 11791 3361 11790 3362 11789 3363 11788
      3363 11789 3372 11782 3359 11768 3354 11778
      3355 11782 3357 11784 3359 11788

$$

Connolly

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 14, 7:34 AM PST	Areal Flood Advisory	SGX	Orange, Riverside	4 hr
Dec 14, 8:09 AM PST	Areal Flood Advisory	SGX	Orange	4 hr
Dec 14, 9:23 AM PST	Areal Flood Advisory	SGX	San Bernardino	4 hr
Dec 14, 11:01 AM PST	Flash Flood Warning Considerable damage threat	SGX	Orange	89 min
Dec 14, 11:46 AM PST	Areal Flood Advisory	SGX	San Diego	3 hr
Dec 14, 1:00 PM PST	Areal Flood Advisory	SGX	Riverside, San Bernardino	3 hr
Dec 14, 1:15 PM PST	Areal Flood Advisory	SGX	San Diego	3 hr
Dec 14, 1:27 PM PST	Flash Flood Warning Considerable damage threat	SGX	Riverside, San Bernardino	108 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive.