Alert archive / California / Flash Flood Watches in 2012

Flash Flood Watch 13, NWS San Diego, CA

September 9, 2012Riverside County, San Bernardino County, San Diego County, California

NWS San Diego, CA issued this flash flood watch at Sep 9, 2012, 7:01 PM PDT for Riverside County, San Bernardino County, San Diego County, California. It took effect at Sep 10, 2012, 10:00 AM PDT. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued
Sep 9, 2012, 7:01 PM PDT (02:01 UTC)
In effect from
Sep 10, 2012, 10:00 AM PDT
Expired
Sep 10, 2012, 5:58 PM PDT
In force
8 hr
Issued by
NWS San Diego, CA
Flood severity
None

Counties Riverside County, CA, San Bernardino County, CA, San Diego County, CA

The radar

The Santa Ana Mts radar (KSOX), 122 km from the middle of the area, began a volume at 02:15 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 00:00Z, 2.0 hours before the alert went out and 145 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 2012-09-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 137 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 00:00Z on 2012-09-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 67 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
137 J/kg
Mixed-layer CIN
-379 J/kg
Mixed-layer LCL
1160 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
67 m²/s²
0-3 km storm-relative helicity
107 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

235 
WGUS66 KSGX 100201
FFASGX

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE SAN DIEGO CA
701 PM PDT SUN SEP 9 2012

...FLASH FLOOD WATCH FOR THE VALLEYS..MOUNTAINS AND DESERTS OF
EXTREME SOUTHWEST CALIFORNIA ON MONDAY..

.DEEP MONSOONAL MOISTURE AND A WEAK AREA OF LOW PRESSURE MOVING
NORTH FROM MEXICO WILL COMBINE TO BRING A THREAT OF HEAVY SHOWERS
AND THUNDERSTORMS THROUGH MONDAY NIGHT. LOCALLY HEAVY RAIN AND
FLASH FLOODING WILL BE POSSIBLE. THE MAIN THREAT WILL DEVELOP WITH
DAYTIME HEATING AND CONTINUE INTO THE EVENING. THE THREAT FOR
HEAVY RAIN WILL DIMINISH LATE MONDAY NIGHT.

CAZ048-050-055-056-058-060>062-101300-
/O.NEW.KSGX.FF.A.0013.120910T1700Z-120911T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS-
701 PM PDT SUN SEP 9 2012

...FLASH FLOOD WATCH IN EFFECT FROM MONDAY MORNING THROUGH MONDAY
EVENING...

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WATCH FOR A PORTION OF SOUTHWEST CALIFORNIA... 
  INCLUDING THE FOLLOWING AREAS...APPLE AND LUCERNE VALLEYS... 
  COACHELLA VALLEY...RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO 
  COUNTY MOUNTAINS...SAN BERNARDINO AND RIVERSIDE COUNTY 
  VALLEYS- THE INLAND EMPIRE...SAN DIEGO COUNTY DESERTS...SAN 
  DIEGO COUNTY MOUNTAINS AND SAN DIEGO COUNTY VALLEYS. 

* FROM LATE MONDAY MORNING THROUGH MONDAY EVENING

* LOW PRESSURE OVER NORTHWEST MEXICO AND DEEP MONSOONAL MOISTURE
  WILL COMBINE TO BRING A THREAT OF LOCALLY HEAVY RAIN AND FLASH
  FLOODING THROUGH MONDAY EVENING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

JAD
3 follow-up statements
936 
WGUS66 KSGX 101007
FFASGX

FLOOD WATCH
NATIONAL WEATHER SERVICE SAN DIEGO CA
307 AM PDT MON SEP 10 2012

...FLASH FLOOD WATCH FOR THE VALLEYS...MOUNTAINS...AND DESERTS OF
EXTREME SOUTHWEST CALIFORNIA FOR LATE MORNING THROUGH EARLY
EVENING TODAY...

.MONSOONAL MOISTURE AND DAYTIME HEATING WILL BRING SCATTERED
THUNDERSTORMS TO THE MOUNTAINS...DESERTS...AND INLAND VALLEYS FROM
LATE MORNING THROUGH EARLY EVENING TODAY. LOCALLY HEAVY RAINFALL
WITH FLASH FLOODING IS POSSIBLE.

CAZ048-050-055-056-058-060>062-102100-
/O.CON.KSGX.FF.A.0013.120910T1700Z-120911T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS-
307 AM PDT MON SEP 10 2012

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 10 AM PDT THIS
MORNING THROUGH THIS EVENING...

THE FLASH FLOOD WATCH CONTINUES FOR

* A PORTION OF SOUTHWEST CALIFORNIA...INCLUDING THE FOLLOWING 
  AREAS...APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY... 
  RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...
   SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND 
  EMPIRE...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS 
  AND SAN DIEGO COUNTY VALLEYS. 

* FROM 10 AM PDT THIS MORNING THROUGH THIS EVENING

* MONSOONAL MOISTURE AND DAYTIME HEATING WILL BRING SCATTERED
  THUNDERSTORMS TO THE MOUNTAINS...DESERTS...AND INLAND VALLEYS
  FROM LATE MORNING INTO THIS EVENING WITH LOCALLY HEAVY RAINFALL
  AND FLASH FLOODING POSSIBLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

17
617 
WGUS66 KSGX 102004
FFASGX

FLOOD WATCH
NATIONAL WEATHER SERVICE SAN DIEGO CA
104 PM PDT MON SEP 10 2012

...FLASH FLOOD WATCH FOR THE VALLEYS...MOUNTAINS...AND DESERTS OF
EXTREME SOUTHWEST CALIFORNIA THROUGH EARLY EVENING TODAY...

.MONSOONAL MOISTURE AND DAYTIME HEATING WILL CONTINUE TO BRING
SCATTERED THUNDERSTORMS TO THE MOUNTAINS...DESERTS...AND INLAND
VALLEYS THROUGH EARLY EVENING TODAY. LOCALLY HEAVY RAINFALL
AND FLASH FLOODING ARE POSSIBLE.

CAZ048-050-055-056-058-060>062-110300-
/O.CON.KSGX.FF.A.0013.000000T0000Z-120911T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS-
104 PM PDT MON SEP 10 2012

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL MIDNIGHT PDT
TONIGHT...

THE FLASH FLOOD WATCH CONTINUES FOR

* A PORTION OF SOUTHWEST CALIFORNIA...INCLUDING THE FOLLOWING
  AREAS...APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...
  RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS... SAN
  BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE...SAN
  DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS AND SAN DIEGO
  COUNTY VALLEYS.

* UNTIL MIDNIGHT PDT TONIGHT.

* MONSOONAL MOISTURE AND DAYTIME HEATING WILL BRING SCATTERED
  THUNDERSTORMS TO THE MOUNTAINS...DESERTS...AND INLAND VALLEYS
  INTO THIS EVENING WITH LOCALLY HEAVY RAINFALL AND FLASH FLOODING
  POSSIBLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

HARRISON
780 
WGUS66 KSGX 110058
FFASGX

FLOOD WATCH
NATIONAL WEATHER SERVICE SAN DIEGO CA
558 PM PDT MON SEP 10 2012

CAZ048-050-055-056-058-060>062-110200-
/O.CAN.KSGX.FF.A.0013.000000T0000Z-120911T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS-
558 PM PDT MON SEP 10 2012

...FLASH FLOOD WATCH IS CANCELLED...

THE FLASH FLOOD WATCH FOR A PORTION OF SOUTHWEST CALIFORNIA HAS
BEEN CANCELLED. MOST OF THE PRECIPITATION HAD ENDED FOR TODAY.
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVERNIGHT IN THE
MOUNTAINS AND DESERTS...BUT WIDESPREAD HEAVY RAIN IS NOT EXPECTED.

$$

MAXWELL

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 9, 5:23 PM PDTSevere Thunderstorm WarningSGXSan Diego45 min
Sep 9, 5:30 PM PDTFlash Flood WarningSGXSan Diego104 min
Sep 9, 7:26 PM PDTBlowing Dust AdvisorySGXRiverside, San Diego3 hr
Sep 10, 12:21 PM PDTAreal Flood AdvisorySGXRiverside, San Bernardino119 min
Sep 10, 1:17 PM PDTSevere Thunderstorm WarningSGXRiverside49 min
Sep 10, 1:29 PM PDTFlash Flood WarningSGXSan Bernardino3 hr
Sep 10, 2:00 PM PDTAreal Flood AdvisorySGXSan Bernardino3 hr
Sep 10, 2:33 PM PDTSevere Thunderstorm WarningSGXOrange, Riverside50 min
Sep 10, 2:42 PM PDTFlash Flood WarningSGXSan Diego93 min
Sep 10, 2:59 PM PDTFlash Flood WarningSGXSan Bernardino2 hr
Sep 10, 3:07 PM PDTSpecial Weather StatementSGXOrange53 min
Sep 10, 4:34 PM PDTAreal Flood AdvisorySGXSan Bernardino116 min

Nearby

Flash Flood Watches in California, 2012Every flash flood watch in 2012

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.