A surge of monsoonal moisture from northern Mexico generated scattered thunderstorms over the mountains of Los Angeles county. Some of these storms produced heavy rain, flash flooding and mud and debris flows.
Every event with a place to put it. 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 episode as NWS LOX wrote it up.
A surge of monsoonal moisture from northern Mexico generated scattered thunderstorms over the mountains of Los Angeles county. Some of these storms produced heavy rain, flash flooding and mud and debris flows.
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 Aug 3, 1:00 PM PST, 2 hours 20 minutes earlier.
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 200 PM PDT SUN AUG 3 2014 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM CENTERED NEAR SAN DIEGO HAS DRAWN IN SIGNIFICANT SUBTROPICAL MOISTURE INTO THE REGION TODAY BRINGING SCATTERED SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS. SOME STORMS MAY PRODUCE HEAVY RAINFALL WITH FLASH FLOODING OVER THE LOS ANGELES MOUNTAINS AND ANTELOPE VALLEY. THE ATMOSPHERE WILL BEGIN TO DRY OUT ON MONDAY...WITH A RETURN OF NIGHT AND MORNING LOW CLOUDS ALONG THE COAST AND NEAR NORMAL TEMPERATURES THROUGH MUCH OF THE WEEK. && .SHORT TERM (TONIGHT-WED)... UPPER LEVEL LOW PRESSURE SYSTEM CENTERED NEAR SAN DIEGO HAS DRAWN UP A SIGNIFICANT AMOUNT OF SUBTROPICAL MOISTURE INTO THE REGION TODAY. GPS PRECIPITABLE WATER SENSORS STILL INDICATING VALUES RANGING BETWEEN 1.7 AND 1.9 INCHES ACROSS LOS ANGELES AND VENTURA COUNTIES THIS AFTERNOON. A BAND OF STRATIFORM RAIN CONTINUES TO PRODUCE SOME LIGHT SHOWERS ACROSS MUCH OF VENTURA AND EASTERN SANTA BARBARA COUNTIES. MEANWHILE...THUNDERSTORM DEVELOPMENT SO FAR THIS AFTERNOON HAS BEEN CONFINED TO THE SAN BERNARDINO RANGE SOUTHWARD. THE THUNDERSTORMS OVER THE MOUNTAINS OF RIVERSIDE AND SAN DIEGO COUNTIES ALREADY HAVE A HISTORY OF PRODUCING HEAVY RAINFALL...SHOWING THE POTENTIAL THAT LOOMS AHEAD FOR OUR AREA. THE MAIN FOCUS THIS AFTERNOON AND EVENING WILL CONTINUE TO BE THE LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY...WHERE A FLASH FLOOD WATCH IS IN EFFECT UNTIL 8 PM. SO FAR...THERE HAS BEEN TOO MUCH CLOUD COVERAGE ACROSS MUCH OF OUR FORECAST AREA TO PROVIDE SUFFICIENT HEATING FOR NECESSARY INSTABILITY FOR THUNDERSTORMS. HOWEVER...DURING THE PAST HOUR...SATELLITE IMAGERY SHOWING SOME BETTER CLEARING ACROSS EASTERN LOS ANGELES COUNTY. THIS SHOULD HELP TO DESTABILIZE THE ATMOSPHERE DURING THE NEXT FEW HOURS. NAM AND GFS MODELS CAPTURE THIS IDEA...SHOWING BEST INSTABILITY TO BE FOCUSED ACROSS EASTERN LOS ANGELES COUNTY THIS AFTERNOON AND EVENING. IN ADDITION TO THE HIGH MOISTURE CONTENT THROUGH THE ENTIRE ATMOSPHERE...SURFACE DEWPOINTS HAVE ALSO CLIMBED SIGNIFICANTLY TODAY ACROSS THE SAN GABRIEL VALLEY WITH VALUES INTO THE LOWER TO MID 70S! UPPER LEVEL WINDS EXPECTED TO BE LESS THAN 10 KNOTS ACROSS LOS ANGELES COUNTY...SO ANY STORM DEVELOPMENT WILL BE SLOW MOVING...WHICH WILL ENHANCE THE FLASH FLOOD POTENTIAL FOR THE LOS ANGELES MOUNTAINS AND ANTELOPE VALLEY. RAINFALL RATES IN EXCESS OF ONE INCH PER HOUR WILL BE POSSIBLE IN THESE AREAS WITH ANY THUNDERSTORM DEVELOPMENT. LATEST GFS AND NAM CONTINUE TO FOCUS HEAVIEST RAINFALL THREAT FOR THE EASTERN SAN GABRIELS AND EASTERN ANTELOPE VALLEY THROUGH THE EVENING HOURS...WITH HIGH RESOLUTION WRF PINPOINTING THIS AREA WITH HIGHER INTENSITY RAINFALL BETWEEN 3 PM AND 8 PM. MAJOR ROADWAYS THAT WILL BE AT RISK FOR FLOODING LATER INCLUDE HIGHWAY 2 IN THE SAN GABRIELS AND HIGHWAY 138 IN THE ANTELOPE VALLEY. THE OTHER AREA TO WATCH CLOSELY THIS AFTERNOON WILL BE THE SAN GABRIEL VALLEY...WITH 18Z NAM MODEL SOUNDINGS SHOWING SOME INCREASED INSTABILITY/CAPE AND WEAK FLOW ALOFT. DESPITE THE SIGNIFICANT CLOUD COVERAGE TODAY...MANY AREAS ARE SEEING VERY WARM TEMPERATURES. OFFSHORE FLOW HAS DEVELOPED ACROSS MUCH OF LOS ANGELES AND VENTURA COUNTIES TODAY...WITH LAX-DAGGETT GRADIENT INCREASING ITS OFFSHORE COMPONENT THROUGH THE DAY (CURRENTLY AT -2.2 MB). OFFSHORE WINDS HAVE GUSTED BETWEEN 35 AND 45 MPH IN THE MOUNTAINS...WITH SOME GUSTS IN THE 25 TO 35 MPH RANGE IN THE VALLEYS. THIS OFFSHORE FLOW IS VERY UNUSUAL IN AUGUST AND HAS CAUSED SOME TEMPERATURES TO SOAR ABOVE 90 DEGREES TODAY IN THE VALLEYS. AREAS WHERE OFFSHORE WINDS DEVELOPED HAVE SEEN DEWPOINTS IN THE 50S AND 60S...BUT THE SAN GABRIEL VALLEY (WHICH HAS BEEN MOSTLY PROTECTED FROM THE OFFSHORE WINDS) HAS SEEN VERY MOIST CONDITIONS WITH DEWPOINTS CLIMBING INTO THE 70S. THIS INCREASED HUMIDITY IS ADDING TO THE HEAT DISCOMFORT ACROSS THE SOUTHLAND TODAY. THE ATMOSPHERE IS EXPECTED TO DRY OUT OVERNIGHT...WITH A RETURN OF SOME LOWER LEVEL CLOUDS OVERNIGHT INTO MONDAY MORNING. EVEN DRIER AIR WILL MOVE INTO THE REGION ON MONDAY AS WESTERLY FLOW ALOFT RETURNS TO SOUTHERN CALIFORNIA. A MORE TYPICAL NIGHT AND MORNING LOW CLOUD AND FOG REGIME WILL ESTABLISH ALONG COASTAL AREAS TUESDAY INTO WEDNESDAY...WITH TEMPERATURES NEAR NORMAL. .LONG TERM (THU-SUN)... LONG RANGE COMPUTER MODELS CONTINUE TO AGREE THAT A COOLER THAN NORMAL PATTERN WILL SHAPE UP FOR THE LATTER PART OF THE WEEK INTO NEXT WEEKEND. THIS IN DUE TO A BAGGY UPPER LEVEL TROUGH OVER THE WEST COAST THAT WILL LIKELY ALLOW FOR LOW CLOUDS AND FOG TO SPREAD INTO THE VALLEYS. NO THUNDERSTORM ACTIVITY IS EXPECTED THROUGH EXTENDED PERIOD. && .AVIATION...03/1800Z... LOW CONFIDENCE WITH 18Z TAFS. THERE WILL BE PLENTY OF MID LEVEL CLOUDS ACROSS THE ENTIRE FORECAST AREA THROUGH THIS EVENING. THIS WILL MAKE FORECASTING STRATUS DIFFICULT. THERE WILL BE A 50 PERCENT CHANCE THAT LIFR/IFR CIGS WILL NOT OCCUR. THERE WILL BE LOCAL GUSTY N TO NE WINDS ACROSS THE LA/VTU COUNTY MOUNTAINS THIS AFTERNOON WHICH COULD CAUSE LOCAL UDDF AND LLWS OVER THE MOUNTAINS AND LA/VTU COUNTIES. THERE IS ALSO A CHANCE OF THUNDERSTORMS FOR LA/VTU COUNTY MOUNTAINS AND ANTELOPE VALLEY WHICH COULD CAUSE ADDITIONAL UDDF NEAR THUNDERSTORMS THROUGH THIS EVE. KLAX...GENERALLY LOW CONFIDENCE IN THE 18Z TAF WITH VFR CIGS EXPECTED THRU MON MORNING. IFR/MVFR CIGS COULD DEVELOP AFTER 10Z. BUT AROUND 50 PERCENT CHANCE.THERE IS ALSO A SLIGHT CHANCE OF THUNDERSTORMS THROUGH 00Z THIS AFTERNOON. KBUR...GENERALLY HI CONFIDENCE IN THE 18Z TAF WITH VFR CIGS EXPECTED THRU MONDAY MORNING. THERE IS ALSO A SLIGHT CHANCE OF THUNDERSTORMS FOR THE AREA THRU SUN. && .MARINE...03/300 PM PDT NO MARINE ISSUES TODAY...EXCEPT FOR SLIGHT CHANCE FOR THUNDERSTORMS THROUGH THIS AFTERNOON ACROSS COASTAL WATERS S OF POINT CONCEPTION. GENERAL OUTLOOK OVER THE NEXT FEW DAYS WILL CONTINUE BE LIGHT TO LOCALLY MODERATE NW FLOW ACROSS THE OUTER WATERS. && .LOX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH (SEE LAXFFALOX). MARINE WEATHER STATEMENT (SEE LAXMWSLOX). && PUBLIC...GOMBERG AVIATION/MARINE...CK SYNOPSIS...GOMBERG WWW.WEATHER.GOV/LOSANGELES
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 200 PM PDT SUN AUG 3 2014 CAZ034>041-044>046-051>054-059-087-088-547-548-041300- SAN LUIS OBISPO COUNTY CENTRAL COAST- SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY- SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY- SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST- LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES- VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS- SANTA MONICA MOUNTAINS RECREATIONAL AREA- SAN LUIS OBISPO COUNTY MOUNTAINS- SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS- LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE- ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY- LOS ANGELES COUNTY SAN FERNANDO VALLEY- LOS ANGELES COUNTY SAN GABRIEL VALLEY- 200 PM PDT SUN AUG 3 2014 THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA. .DAY ONE... TODAY AND TONIGHT THE THREAT OF THUNDERSTORMS WILL NOW BE CONFINED TO LOS ANGELES COUNTY AND THE ADJACENT COASTAL WATERS THROUGH THIS EVENING...WITH ISOLATED LIGHT SHOWERS CONTINUING ACROSS VENTURA COUNTY. THE GREATEST THREAT OF THUNDERSTORMS WILL BE IN THE LOS ANGELES COUNTY MOUNTAINS AND ANTELOPE VALLEY. A FLASH FLOOD WATCH IS IN EFFECT FOR THESE AREAS DUE TO THE POTENTIAL FOR HEAVY RAIN AND SLOW STORM MOVEMENT. THE THREAT OF THUNDERSTORMS WILL DIMINISH OVERNIGHT. * FLOOD WATCH................SEE WGUS66 KLOX - FFALOX FOR DETAILS * * MARINE WEATHER STATEMENT...SEE FZUS76 KLOX - MWSLOX FOR DETAILS * .DAYS TWO THROUGH SEVEN... MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. GOMBERG
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE OXNARD CA
327 PM PDT SUN AUG 3 2014
CAZ054-059-548-032330-
ANTELOPE VALLEY CA-LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA
MONICA RANGE CA-LOS ANGELES COUNTY SAN GABRIEL VALLEY CA-
327 PM PDT SUN AUG 3 2014
...SIGNIFICANT WEATHER ADVISORY FOR THE SAN GABRIEL MOUNTAINS IN
EASTERN LOS ANGELES COUNTY UNTIL 430 PM PDT...
AT 320 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 11 MILES NORTHEAST OF MOUNT WILSON...OR 14 MILES
NORTHEAST OF SIERRA MADRE. THIS STORM WAS NEARLY STATIONARY.
HAIL UP TO THE SIZE OF PENNIES IS EXPECTED WITH THIS STORM...ALONG
WITH HEAVY RAIN AND FREQUENT DANGEROUS CLOUD TO GROUND LIGHTNING.
* LOCATIONS IMPACTED INCLUDE...FALLING SPRINGS...MOUNT BALDY...AND
RURAL MOUNTAIN ROADS AROUND HIGHWAY 2.
IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.
LAT...LON 3427 11765 3424 11765 3424 11766 3414 11768
3413 11769 3417 11801 3443 11812 3447 11765
3427 11764
TIME...MOT...LOC 2224Z 145DEG 2KT 3432 11790
KAPLAN/GOMBERGThe Santa Ana Mts radar (KSOX), 58 km away, was scanning. The volume nearest the first event began at 23:18 UTC.
2 flash flood. Local standard time, as filed.
Strong thunderstorms produced heavy rain and flash flooding along Highway 39 at Crystal Lake Road. No injuries were reported.
Strong thunderstorms produced heavy rain and flash flooding near the intersection of Cattle Canyon Road and East Fork Road. No injuries were reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2014Every state in 2014This day in weather historyWarnings in California, August 2014
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: 536425, 536426.