1 flash flood, as filed by the National Weather Service.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Los Angeles, CA wrote its last area forecast discussion before the first event at Sep 3, 2:15 AM PST, 10 hours 45 minutes earlier.
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 315 AM PDT WED SEP 3 2003 FAIRLY TYPICAL EARLY SEPTEMBER WX PATTERN ACROSS THE DISTRICT... WITH BOTH MONSOON MOISTURE AND MARINE LAYER TO DEAL WITH. MONSOON CONVECTION DURING TUE AFTERNOON WAS ENHANCED BY A VORT MAX OFF PT CONCEPTION. THIS VORT CENTER IS NOW MOVING FURTHER NORTH ALONG THE CENTRAL COAST...AND HAS TAKEN THE TSRA ACTIVITY WITH IT NW INTO THE SAN JOAQUIN VALLEY. ATMOS IS QUITE MOIST AT MID LEVELS ESPECIALLY SOUTH AND EAST OF THE FCST AREA...WITH THE 00Z NKX SOUNDING SHOWING SATURATION ABOVE 700 MB AND PRECIP WATER OF 1.87 INCHES. ETA DOES BRING ANOTHER WEAK VORT MAX THROUGH THE AREA TODAY WHICH COULD HELP TO TRIGGER CONVECTION ALONG THE AFTERNOON HEATING. WILL MAINTAIN SLIGHT CHANCE POPS THIS AFTERNOON AND EVENING FOR THE MTNS...ANTELOPE VALLEY AND INTERIOR SLO VALLEYS. OTHERWISE...MARINE LAYER IS SOLID AGAIN THIS MORNING ALONG THE CENTRAL COAST...BUT RATHER MIXED OUT AND PATCHY SOUTH OF POINT CONCEPTION. THERE IS SOME REDEVELOPMENT ACROSS THE INNER WATERS AT THIS TIME...AND WILL KEEP PATCHY LOW CLOUDS AND FOG IN THE FCST FOR COASTAL AREAS THIS MORNING. TEMPS TODAY SHOULD BE SLIGHTLY WARMER INLAND AS THICKNESSES RISE A BIT. FOR THURSDAY...MONSOON MOISTURE BEGINS TO ERODE ACROSS THE FCST AREA AS THE MID LEVEL FLOW VEERS MORE TO THE SSW. WILL KEEP SLIGHT CHANCE POPS ACROSS THE VTU/LA MTNS AND ANTELOPE VALLEY AS THERE COULD BE JUST ENOUGH MOISTURE LINGERING ACROSS THESE AREAS TO GENERATE SOME SHRA/TSRA ACTIVITY. CONDITIONS ELSEWHERE SHOULD BE SIMILAR TO TODAY... WITH MARINE LAYER MOST SOLID ON THE CENTRAL COAST AND PATCHY FURTHER SOUTH. DRY SW FLOW ALOFT SPREADS ACROSS THE DISTRICT ON FRIDAY...PUTTING AN END TO THE TSTM THREAT. UPPER RIDGE REMAINS OVER THE AREA FRI AND SAT...WITH ONSHORE GRADIENTS REMAINING WEAK TO MODERATE. THIS WILL KEEP THE MARINE LAYER CONFINED TO COASTAL SECTIONS AND ALLOW FOR CONTINUED HOT TEMPERATURES INLAND. UPPER RIDGE BREAKS DOWN SUNDAY AS A STRONG UPPER TROF MOVES INTO NRN CA. THIS HERALDS A PATTERN CHANGE... WITH A LONGWAVE UPPER TROF SETTING UP SHOP ALONG THE WEST COAST INTO EARLY NEXT WEEK. FALLING HEIGHTS...CYCLONIC FLOW ALOFT AND INCREASED ONSHORE FLOW WILL ALLOW FOR AN INCREASED MARINE LAYER...WITH COOLER TEMPS...AND BREEZY CONDITIONS ACROSS THE MTNS AND DESERTS. ANOTHER ASPECT OF SEPTEMBER WEATHER COULD TAKE SHAPE ACROSS THE AREA LATER NEXT WEEK IF TONIGHTS GFS IS CORRECT. THIS MODEL SHOWS A STRONG INSIDE SLIDER MOVING ACROSS THE GREAT BASIN WED AND THU...RESULTING IN OFFSHORE FLOW FOR SO CAL. GFS DOES TEND TO OVERDO OFFSHORE FLOW EVENTS AND THIS IS FAR IN THE FUTURE IN ANY CASE...BUT WILL BE INTERESTING TO SEE WHAT HAPPENS WITH LATER MODEL RUNS. LAX 000. JACOBSON .LOX...NONE.
CAZ034>041-044>047-051>054-059-087-088-040100- HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 600 AM PDT WED SEP 3 2003 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA. .DAY ONE... THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE DESERTS AND MOUNTAINS AS WELL AS THE INTERIOR PORTIONS OF SAN LUIS OBISPO COUNTY DURING THE AFTERNOON AND EVENING. .DAYS TWO THROUGH SEVEN... THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE DESERTS AND THE VENTURA AND LOS ANGELES COUNTY MOUNTAINS ON THURSDAY. OTHERWISE NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. JACOBSON
The national radar mosaic for the moment the first event began.
1 flash flood. Local standard time, as filed.
Strong monsoonal thunderstorms moved across the Antelope Valley, producing heavy and flash flooding. Along Largo Vista Road, seven miles ESE of Pearblossom, flash flooding was reported. Due to the flash flooding, one vehicle was stranded and abandoned.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2003Every state in 2003This day in weather historyWarnings in California, September 2003
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5375192.