Alert archive / California / Flash Flood Warnings in 2010

Flash Flood Warning 21, NWS San Diego, CA

August 26, 2010Riverside County, California

NWS San Diego, CA issued this flash flood warning at Aug 26, 2010, 3:07 PM PDT for Riverside County, California. It was in force for 58 min. 1 report 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
Aug 26, 2010, 3:07 PM PDT (22:07 UTC)
Expired
Aug 26, 2010, 4:05 PM PDT
In force
58 min
Issued by
NWS San Diego, CA
Area
Storm-based polygon
Flood severity
None

County Riverside County, CA

The radar

The Santa Ana Mts radar (KSOX), 45 km from the middle of the area, began a volume at 22:10 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.

What was reported inside it

TimeReportWhereRemark
Aug 26, 3:30 PM PDTHEAVY RAIN 0.49Winchester, CAALERT ID 248 WINCHESTER MEASURED 0.49 INCHES BETWEEN 1440-1530 PDT WITH RAINFALL RATES OVER 1 INCH PER HOUR BETWEEN 1500-1515 PDT.

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, 10.1 hours before the alert went out and 103 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 2010-08-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 731 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 2010-08-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 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
731 J/kg
Mixed-layer CIN
-622 J/kg
Mixed-layer LCL
1922 m above ground
0-6 km bulk shear
3 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
72 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.

979 
WGUS56 KSGX 262207
FFWSGX
CAC065-270000-
/O.NEW.KSGX.FF.W.0021.100826T2207Z-100827T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN DIEGO CA
307 PM PDT THU AUG 26 2010

THE NATIONAL WEATHER SERVICE IN SAN DIEGO HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  WEST CENTRAL RIVERSIDE COUNTY IN SOUTHWEST CALIFORNIA...
  THIS INCLUDES THE CITY OF HEMET...

* UNTIL 500 PM PDT

* AT 301 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  A STRONG THUNDERSTORM CAPABLE OF PRODUCING FLASH FLOODING FROM A   
  STORM OVER THE WARNED AREA.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO PERRIS...
  SUN CITY...AND HEMET.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE.

&&

LAT...LON 3386 11707 3371 11693 3356 11719 3362 11730
      3375 11739

$$

SS
2 follow-up statements
584 
WGUS76 KSGX 262252
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
352 PM PDT THU AUG 26 2010

CAC065-270000-
/O.CON.KSGX.FF.W.0021.000000T0000Z-100827T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
RIVERSIDE CA-
352 PM PDT THU AUG 26 2010

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 500 PM PDT FOR WEST
CENTRAL RIVERSIDE COUNTY...

AT 346 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO 
INDICATE HEAVY RAIN PRODUCING FLASH FLOODING OVER THE WARNED AREA. 
WHILE THE STORM HAS WEAKENED...ADDITIONAL RAINFALL AND RUNOFF WILL 
CONTINUE THE THREAT OF FLASH FLOODING.

LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO SUN 
CITY...PERRIS AND HEMET.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY. MOVE TO HIGHER GROUND.

&&

LAT...LON 3386 11707 3371 11693 3356 11719 3362 11730
      3375 11739

$$

SS
495 
WGUS76 KSGX 262305
FFSSGX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SAN DIEGO CA
405 PM PDT THU AUG 26 2010

CAC065-262315-
/O.CAN.KSGX.FF.W.0021.000000T0000Z-100827T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
RIVERSIDE CA-
405 PM PDT THU AUG 26 2010

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR WEST CENTRAL
RIVERSIDE COUNTY...

THE LINE OF STORMS IN WESTERN RIVERSIDE COUNTY HAS DISSIPATED AND A 
FLASH FLOOD WARNING IS NO LONGER IN EFFECT.

LAT...LON 3386 11707 3371 11693 3356 11719 3362 11730
      3375 11739

$$

SS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 26, 10:53 AM PDTFlash Flood WarningSGXRiverside, San Bernardino37 min
Aug 26, 11:29 AM PDTFlash Flood WarningSGXRiverside, San Bernardino3 hr
Aug 26, 12:36 PM PDTFlash Flood WarningSGXRiverside, San Diego94 min
Aug 26, 12:59 PM PDTFlash Flood WarningSGXSan Bernardino78 min
Aug 26, 1:01 PM PDTSevere Thunderstorm WarningSGXSan Diego44 min
Aug 26, 2:36 PM PDTSevere Thunderstorm WarningSGXRiverside54 min
Aug 26, 2:55 PM PDTSpecial Weather StatementSGX65 min
Aug 26, 3:30 PM PDTSpecial Weather StatementSGX60 min
Aug 26, 3:32 PM PDTSevere Thunderstorm WarningSGXRiverside22 min
Aug 26, 3:51 PM PDTSevere Thunderstorm WarningSGXSan Bernardino54 min
Aug 26, 3:56 PM PDTFlash Flood WarningSGXSan Bernardino2 hr

Nearby

Flash Flood Warnings in California, 2010Every flash flood warning in 2010

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; radar from the NEXRAD Level II archive.