On the evening of the 15th, a significant marine push occurred and moved well inland toward the west side of the central San Joaquin Valley as an upper-level trough moved onshore; Pacheco Pass experienced a 42 mph wind gust that evening. That gust prompted a wind advisory that was issued during that evening for the west side of the San Joaquin Valley for Fresno and Merced Counties.
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 HNX wrote it up.
On the evening of the 15th, a significant marine push occurred and moved well inland toward the west side of the central San Joaquin Valley as an upper-level trough moved onshore; Pacheco Pass experienced a 42 mph wind gust that evening. That gust prompted a wind advisory that was issued during that evening for the west side of the San Joaquin Valley for Fresno and Merced Counties. Temperatures on the 16th fell several degrees from the previous day, including in the San Joaquin Valley. The trough remained over the region through the 17th. Temperatures were several degrees normal on both of these days, with highs in the central and southern San Joaquin Valley only in the mid to upper 80s for high temperatures, and upper 80s to lower 90s in the desert areas of eastern Kern County.
The upper-level ridge returned to interior central California by the 18th. Temperatures rose to a few degrees above average by the 19th. The weather has remained mainly dry through September 22nd, with mainly cumulus cloud buildups over the southern Sierra Nevada crest.
Off the coast of California, a low-pressure system developed within the ridge and drifted toward the coast. By September 23rd, the flow around this low drew subtropical moisture into southern and central California. The ridge remained the dominant large-scale feature over central California, bringing unseasonably warm weather to the region. Fresno had a high of 101 degrees on the 23rd, the third, and last, time Fresno say triple digits in September. With a very warm and unstable airmass, thunderstorms developed across the region. Although there was moisture in the mid-level of the atmosphere, the lowest levels remained dry, and the thunderstorms were mostly dry with numerous lightning strikes. The lightning triggered several wildfires in Kern County, with a few fires started in Tulare County. Outflow winds from the thunderstorms toppled power poles in northeast Bakersfield, knocking out power to over three thousand people. In the Mojave Desert northeast of Mojave, winds blew a big rig over on State Route 58.
Clouds from the showers and thunderstorms remained over the central California interior through September 24th, keeping low temperatures unseasonably warm. Fresno set record high minimum temperature records on both the 23rd and 24th.|A strong cold front moved into central California on September 25th, bringing sharp drops in temperature. The highs at Bakersfield and Fresno on the 24th were 97 degrees; the next day, the high at Bakersfield was only 80 and Fresno was only a degree warmer. The unseasonably cold airmass lingered over the region the next two days, slowly mixing out. A weak upper-level ridge boosted high temperatures over the central and southern San Joaquin Valley into the mid to upper 90s on September 29th, but highs fell back to near normal the next day. A weak surge of monsoonal moisture at the end of the month brought isolated thunderstorms to the Southern Sierra Nevada crest.
Bakersfield had five days in September with highs at or above 100 degrees, and Fresno had 3 triple-digit days. For the summer, through the end of September, Bakersfield had 30 days with highs at or above 100 degrees, while Fresno had 28 days. The average temperature for September was 80.3 degrees at both Bakersfield and Fresno. This was the third warmest September on record for Fresno, while Bakersfield tied for its ninth warmest September on record.
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 Hanford, CA wrote its last area forecast discussion before the first event at Sep 23, 2:01 PM PST, 3 hours 39 minutes earlier.
AREA FORECAST DISCUSSION...CORRECTED AVIATION SECTION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 301 PM PDT FRI SEP 23 2011 .SYNOPSIS... TROPICAL MOISTURE MOVING NORTHWARD INTO THE REGION WILL PRODUCE ISOLATED TO SCATTERED THUNDERSTORMS...PRIMARILY OVER THE KERN COUNTY MOUNTAINS THROUGH SATURDAY. OTHERWISE...HIGH PRESSURE WILL CONTINUE TO BRING ABOVE NORMAL TEMPERATURES. COOLING OVER THE ARE IS EXPECTED BY SUNDAY AS LOWER PRESSURE INVADES CALIFORNIA. && .DISCUSSION...A FEW SHOWERS DEVELOPING OVER THE SIERRA NEVADA THIS AFTERNOON. OTHERWISE MOST OF THE SHOWER ACTIVITY HAS REMAINED TOWARDS SANTA BARBARA AND SAN LOUIS OBISPO COUNTIES. THINK THE CONVECTIVE THREAT FOR THUNDERSTORMS WILL CONTINUE OVER THE SOUTH HALF OF THE DISTRICT INTO THE EARLY EVENING. AN UPPER LOW OFF POINT CONCEPTION WILL LIFT NORTHWARD OFF THE CENTRAL COAST THIS EVENING TAKING THE BEST DYNAMIC FORCING TOWARDS CENTRAL VALLEY AND YOSEMITE AREA TONIGHT. MODELS PROG THE UPPER LOW TO WEAKEN BUT PUSH EAST OVER CENTRAL CALIFORNIA SATURDAY. INSTABILITY DECREASES TOWARDS THE COAST BUT CONDITIONS REMAIN UNSTABLE OVER THE SIERRA FOR A CONTINUED THREAT OF THUNDER. TEMPERATURES SHOULD BE COOLER SATURDAY DUE TO SYNOPTIC COOLING WITH THE COASTAL LOW. A UPPER TROUGH FROM THE GULF OF ALASKA WILL REACH CALIFORNIA SUNDAY. THUS THE COOLING TREND WILL CONTINUE THROUGH THE WEEKEND BUT WITH STRONGER WINDS OVER MUCH OF THE AREA. GUSTY WINDS SHOULD DEVELOP SUNDAY AFTERNOON ALONG MOUNTAINS PASSES OF THE WEST SIDE OF THE VALLEY THEN SHIFT TO THE KERN COUNTY MOUNTAIN PASSES AND HIGH DESERT. MODELS PROG BEST DYNAMICS AND PRECIPITATION ALONG A COLD FRONT OVER NCAL BUT THE FRONT FALLS APART AS IT APPROACHES THE N SAN JOAQUIN VALLEY. THE COOL TEMPERATURES WILL BE SHORT LIVED AS AN UPPER RIDGE OVER THE EAST PACIFIC BUILD EAST OVER CALIFORNIA MONDAY. THE HIGH WILL CONTINUE TO EXPAND INTO THE INTERIOR WEST BUT MODELS SHOW THE CENTER OF THE RIDGE REMAINING NEAR CALIFORNIA. THUS WARM AND DRY CONDITIONS MAY CONTINUE THROUGH NEXT WEEK. && .AVIATION... VFR CONDITIONS WILL PREVAIL OVER THE SAN JOAQUIN VALLEY THROUGH 00Z SUNDAY. SCATTERED THUNDERSTORMS CAN BE EXPECTED OVER MOUNTAIN AND DESERT AREAS THROUGH 06Z SATURDAY WITH LOCAL MVFR CEILINGS IN THUNDERSTORMS OVER THE SIERRA. ISOLATED THUNDESTORMS WILL DEVELOP AGAIN OVER MOUNTAIN AREAS AFTER 20Z SATURDAY. && .AIR QUALITY ISSUES... ON FRIDAY SEPTEMBER 23 2011... UNHEALTHY FOR SENSITIVE GROUPS IN FRESNO... KERN... KINGS AND TULARE COUNTIES. FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG && .HNX WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING CAZ095. && PUBLIC...MV AVN/FW...MENDENHALL SYNOPSIS...WP WEATHER.GOV/HANFORD
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 936 AM PDT FRI SEP 23 2011 CAZ096-097-241645- SIERRA NEVADA FROM YOSEMITE TO KINGS CANYON- TULARE COUNTY MOUNTAINS- 936 AM PDT FRI SEP 23 2011 ...ISOLATED THUNDERSTORMS TODAY THROUGH SATURDAY EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE HIGHER ELEVATIONS OF THE SOUTHERN SIERRA NEVADA. .DAY ONE...TODAY AND TONIGHT THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS TODAY AND TONIGHT. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS SATURDAY AND SUNDAY. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION IS NOT ANTICIPATED. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT OR UNUSUAL CONDITIONS TO THE NATIONAL WEATHER SERVICE. CAZ089-241645- WEST CENTRAL SAN JOAQUIN VALLEY- 936 AM PDT FRI SEP 23 2011 ...ISOLATED THUNDERSTORMS TODAY AND TONIGHT... THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WEST CENTRAL SAN JOAQUIN VALLEY. .DAY ONE...TODAY AND TONIGHT THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS TODAY AND TONIGHT. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY HAZARDOUS WEATHER IS NOT EXPECTED. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION IS NOT ANTICIPATED. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT OR UNUSUAL CONDITIONS TO THE NATIONAL WEATHER SERVICE. CAZ091>095-241645- SOUTHWESTERN SAN JOAQUIN VALLEY-SOUTHEASTERN SAN JOAQUIN VALLEY- MARIPOSA MADERA AND FRESNO COUNTY FOOTHILLS- TULARE COUNTY FOOTHILLS-KERN COUNTY MOUNTAINS- 936 AM PDT FRI SEP 23 2011 ...RED FLAG WARNING AND ISOLATED TO SCATTERED THUNDERSTORMS... THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN SAN JOAQUIN VALLEY...THE FOOTHILLS EAST OF THE SAN JOAQUIN VALLEY...AND THE MOUNTAINS AND DESERT OF KERN COUNTY. .DAY ONE...TODAY AND TONIGHT A RED FLAG WARNING IS IN EFFECT UNTIL 1100 PM TONIGHT FOR THE KERN COUNTY MOUNTAINS SOUTH AND TO THE WEST OF HIGHWAY 58. THERE WILL BE A CHANCE OF THUNDERSTORMS TODAY AND TONIGHT WITH THE GREATEST CHANCE IN THE FRAZIER PARK AREA. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY HAZARDOUS WEATHER IS NOT EXPECTED. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION IS NOT ANTICIPATED. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT OR UNUSUAL CONDITIONS TO THE NATIONAL WEATHER SERVICE. CAZ098-099-241645- INDIAN WELLS VALLEY-SOUTHEASTERN KERN COUNTY DESERT- 936 AM PDT FRI SEP 23 2011 ...ISOLATED THUNDERSTORMS TODAY THROUGH SATURDAY EVENING... THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE KERN COUNTY DESERTS. .DAY ONE...TODAY AND TONIGHT THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS TODAY AND TONIGHT. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS SATURDAY. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION IS NOT ANTICIPATED. WEATHER SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT OR UNUSUAL CONDITIONS TO THE NATIONAL WEATHER SERVICE. WP
The Los Angeles radar (KVTX), 108 km away, was scanning. The volume nearest the first event began at 01:39 UTC.
2 thunderstorm wind. Local standard time, as filed.
A severe thunderstorm toppled a tree and a power pole. In Bakersfield 3723 customers lost power.
A big rig was blown over in Highway 58 near mile marker 170 due to a severe thunderstorm wind gust.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2011Every state in 2011This day in weather historyWarnings in California, September 2011
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: 350029, 350030.