Alert archive / California / Flash Flood Watches in 2021

Flash Flood Watch 3, NWS San Diego, CA

March 10, 2021Orange County, Riverside County, San Diego County, California

NWS San Diego, CA issued this flash flood watch at Mar 10, 2021, 2:02 PM PST for Orange County, Riverside County, San Diego County, California. It was in force for 38 hr.

The area

The counties it named.

The facts

Issued
Mar 10, 2021, 2:02 PM PST (22:02 UTC)
Expired
Mar 12, 2021, 4:00 AM PST
In force
38 hr
Issued by
NWS San Diego, CA
Flood severity
None

Counties Orange County, CA, Riverside County, CA, San Diego County, CA

The radar

The San Diego radar (KNKX), 65 km from the middle of the area, began a volume at 22:05 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, 10.0 hours before the alert went out and 83 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 2021-03-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 106 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-03-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 59 square meters per square second.1939587897117136156Sfc1 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
106 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
664 m above ground
0-6 km bulk shear
100 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
154 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted.

030 
WGUS66 KSGX 102202
FFASGX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service San Diego CA
202 PM PST Wed Mar 10 2021

CAZ057-554-110615-
/O.NEW.KSGX.FF.A.0003.210310T2202Z-210312T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Ana Mountains and Foothills-Orange County Inland Areas-
Including the cities of Mission Viejo, Garden Grove, Fullerton, 
Irvine, Orange, Anaheim, and Santa Ana
202 PM PST Wed Mar 10 2021

...FLASH FLOOD WATCH IN EFFECT THROUGH THURSDAY EVENING...

The National Weather Service in San Diego has issued a

* Flash Flood Watch for the Silverado and Bond Burn Scars in Orange 
  County.

* Through Thursday evening

* Scattered showers and isolated thunderstorms will continue through 
  Thursday evening, with the potential for heavy downpours.

* This additional rain of one-half to three-quarters of an inch, may 
  lead to additional debris flows in and around the burn scars.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away or be swept away. River banks and culverts can become 
unstable and unsafe.

&&

$$

Brotherton
3 follow-up statements
128 
WGUS66 KSGX 110704
FFASGX

Flood Watch
National Weather Service San Diego CA
1104 PM PST Wed Mar 10 2021

CAZ057-554-112200-
/O.CON.KSGX.FF.A.0003.000000T0000Z-210312T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Ana Mountains and Foothills-Orange County Inland Areas-
Including the cities of Mission Viejo, Garden Grove, Fullerton, 
Irvine, Orange, Anaheim, and Santa Ana
1104 PM PST Wed Mar 10 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH THURSDAY EVENING...

The Flash Flood Watch continues for

* Flash Flood Watch for the Silverado and Bond Burn Scars in Orange 
  County.

* Through Thursday evening

* Scattered showers and isolated thunderstorms will continue through 
  Thursday evening, with the potential for heavy downpours.

* This additional rain of one-half to three-quarters of an inch, may 
  lead to additional debris flows in and around the burn scars.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away or be swept away. River banks and culverts can become 
unstable and unsafe.

&&

$$

Gregoria
729 
WGUS66 KSGX 111605
FFASGX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service San Diego CA
805 AM PST Thu Mar 11 2021

CAZ057-554-120600-
/O.EXT.KSGX.FF.A.0003.000000T0000Z-210312T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Ana Mountains and Foothills-Orange County Inland Areas-
Including the cities of Mission Viejo, Garden Grove, Fullerton, 
Irvine, Orange, Anaheim, and Santa Ana
805 AM PST Thu Mar 11 2021

...FLASH FLOOD WATCH NOW IN EFFECT THROUGH LATE TONIGHT...

The Flash Flood Watch is now in effect for

* For the Silverado and Bond Burn Scars in Orange County.

* Through late tonight

* Scattered showers and isolated thunderstorms will continue through 
  late tonight, with the potential for heavy downpours. There will 
  likely be a lull in the activity during the day today, with 
  renewed activity beginning around sunset and continuing through 
  late tonight.

* Rain rates around 0.3" per hour could trigger debris flows once 
  again in and near the Silverado and Bond Burn Scars.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not enter or cross flowing water or water of unknown depth.

Stay away or be swept away. River banks and culverts can become 
unstable and unsafe.

&&

$$

Brotherton
145 
WGUS66 KSGX 120539
FFASGX

Flood Watch
National Weather Service San Diego CA
939 PM PST Thu Mar 11 2021

CAZ057-554-121200-
/O.CON.KSGX.FF.A.0003.000000T0000Z-210312T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Ana Mountains and Foothills-Orange County Inland Areas-
Including the cities of Mission Viejo, Garden Grove, Fullerton, 
Irvine, Orange, Anaheim, and Santa Ana
939 PM PST Thu Mar 11 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 4 AM PST FRIDAY...

The Flash Flood Watch continues for

* For the Silverado and Bond Burn Scars in Orange County.

* Until 4 AM PST Friday

* Isolated showers will continue to be possible which could impact 
  the burn scars.

* Rain rates around 0.3" per hour could trigger debris flows once 
  again in and near the Silverado and Bond Burn Scars.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Do not enter or cross flowing water or water of unknown depth.

Stay away or be swept away. River banks and culverts can become 
unstable and unsafe.

&&

$$

Gregoria

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 10, 11:21 AM PSTBeach Hazards StatementSGXOrange, San Diego15 hr
Mar 10, 12:40 PM PSTSpecial Weather StatementSGXSan Diego50 min
Mar 10, 12:43 PM PSTSpecial Marine WarningSGX32 min
Mar 10, 2:22 PM PSTWinter Weather AdvisorySGXOrange, Riverside, San Bernardino, San Diego20 hr

Nearby

Flash Flood Watches in California, 2021Every flash flood watch 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.