A northwest surge of tropical moisture during the Labor Day weekend produced strong thunderstorms over the Kern County Mountains during the late afternoon of September 3. These thunderstorms produced heavy rain which caused flash flooding in the Frazier Park and Pine Mountain Club areas.
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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.
A northwest surge of tropical moisture during the Labor Day weekend produced strong thunderstorms over the Kern County Mountains during the late afternoon of September 3. These thunderstorms produced heavy rain which caused flash flooding in the Frazier Park and Pine Mountain Club areas. The thunderstorms spread northward through the San Joaquin Valley along an outflow boundary which also produced wind gusts between 40 and 50 mph and blowing dust which reduced visibility to near zero.
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 3, 4:00 AM PST, 7 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service San Joaquin Valley - Hanford CA 500 AM PDT Sun Sep 3 2017 .SYNOPSIS... Temperatures will remain above normal through at least the middle of next week. Showers and thunderstorms will be possible in the mountains and desert areas each day mainly in the afternoon and evening. Additional moisture over the area as remnants of tropical storm Lidia pass by offshore will also create a slight chance for showers and thunderstorms in portions of the San Joaquin Valley today through Labor Day. && .DISCUSSION... The upper ridge bringing very hot conditions to central California is weakening and shifting eastward under the influence of weak low pressure spinning off the California coast while tropical system Lidia treks northwestward from northern Baja. Enhanced moisture in the southeasterly flow between the synoptic features has produced some showers and small thunderstorms across Kern County overnight. Radar shows a few showers remnants currently drifting northwestward through the San Joaquin Valley. Temperatures continue to run quite warm, most notably in the south Valley, where the temperature at Meadows Field Bakersfield has not yet dropped below 90 degrees. The weakening ridge along with effects of increasing moisture will produce slightly lower temperatures today, though still hot enough to cause health risks to persons sensitive to heat. A heat advisory remains in effect today for the San Joaquin Valley, foothills and Kern County mountains below 5000 ft. Mid level moisture will continue to advect over the area as Lidia continues to track northwest to west through Labor Day. This will maintain thunderstorm chances over the mountains and desert areas, with slight chances in mainly the southern portions of the Valley today through Labor Day. Temperatures will continue to trend downward on Labor Day as high pressure continues to weaken. Flow remains southeastward Tuesday and Wednesday as the cyclonic circulation drifts northward. This will provide enough mid level moisture to keep thunderstorm chances in the mountain and desert zones each afternoon and evening, while temperatures lower a little closer to climo. By Thursday a developing trough approaching from the north will produce a drier onshore southwesterly flow, bringing an end to the thunderstorm threat and lowering temperature to at or slightly below normal into next weekend. && .AVIATION... Areas of smoke from near Yosemite National Park down through Sequoia National Forest from associated wildfires producing local IFR conditions over the Southern Sierra Nevada and adjacent foothills and MVFR visibility in the San Joaquin Valley for the next 24 hours. Scattered showers and isolated thunderstorms are expected over the Southern Sierra Nevada and Tehachapi Mountains producing mountain obscurations. Otherwise, VFR conditions can be expected the remainder of the time over the Central CA Interior during the next 24 hours. && .AIR QUALITY ISSUES... Please see SFOAQAHNX for an Air Quality Alert On Sunday September 3 2017... Unhealthy for sensitive groups in Fresno... Kern... Kings... Madera... Merced and Tulare Counties and Sequoia National Park and Forest. Further information is available at Valleyair.org && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.php for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... Heat Advisory until 9 PM PDT this evening CAZ089>095. && public...JEB avn/fw...DS synopsis...JEB weather.gov/hanford
The San Joaquin Valley radar (KHNX), 95 km away, was scanning. The volume nearest the first event began at 19:28 UTC.
10 thunderstorm wind, 9 dust storm, 6 debris flow, 1 lightning. Local standard time, as filed.
A family of three were struck by lightning and injured while wilderness backpacking at Sequoia National Park.
California Highway Patrol reported road flooding and debris due to heavy rainfall near Compagnoni St. and Taft Highway in Castle Ranch.
California Highway Patrol reported power lines were downed by thunderstorm winds across the northbound lanes of State Route 184 near Sunset Blvd 3 miles south of Lamont.
California Highway Patrol reported a tree down on State Route 204 due to strong winds 4NW Bakersfield.
California Highway Patrol reported tree branches downed from thunderstorm wind gusts 13 ENE Keene.
California Highway Patrol reported several tree branches down on State Route 178 due to strong thunderstorm winds in East Bakersfield.
California Highway Patrol reported a mud slide and road flooding due to heavy rainfall on southbound State Route 99 just north of White Ln. in Bakersfield.
California Highway Patrol reported a mud slide in the right lane of State Route 99 at Ming Ave. to State Route 58 in Bakersfield.
California Highway Patrol reported power lines downed across Stockdale Highway west of Rosedale from strong thunderstorm winds.
California Highway Patrol reported downed power poles and power lines near Interstate 5 just south of Stockdale Highway 1SE of Buttonwillow. The downed power lines caused brush fires.
Received a public report through Social Media that showed a building under construction damaged by thunderstorm wind gusts near State Route 99 and Berkshire Rd. in Bakersfield.
California Highway Patrol reported a downed tree from thunderstorm winds on Airport Dr. and West China Grade loop in Bakersfield.
California Highway Patrol reported flooding and debris on San Emidio St. in Lamont.
California Highway Patrol reported a large tree branch downed by thunderstorm wind gusts in the right lane of State Route 99 near East Court Ave. in Pixley.
California Highway Patrol reported downed power lines from thunderstorm wind gusts across the roadway on Lost Hills Rd. near Lokern Rd. 1NW McKittrick.
California Highway Patrol reported State Route 99 was closed in both directions for about an hour due to power poles downed by thunderstorm wind gusts and a mud slide onto the road near Panama Lane in Bakersfield.
California Highway Patrol reported a power pole leaning due to dust storm winds at Ave. 232 and Rd. 56 west of Tulare.
California Highway Patrol reported power lines and power poles downed for dust storm winds on Stockdale Highway near Nord Ave. west of Bakersfield.
California Highway Patrol reported a tree downed by dust storm winds near 14th Ave. and Iona Ave. south of Armona.
California Highway Patrol reported road flooding and mud debris near Cecil Ave. and State Route 99 in Delano.
California Highway Patrol reported power lines downed from dust storm winds in the roadway on State Route 210 near Rd. 74 southwest of Dinuba.
California Highway Patrol reported a tree downed from dust storm wind gusts fell on a vehicle near East Douglas Ave. and North Gowdy St. in Visalia.
California Highway Patrol reported a downed tree from dust storm winds in the roadway on Alturas Dr. near Columbus St. in northeast Bakersfield.
California Highway Patrol reported downed power lines from dust storm winds in the roadway on State Route 201 near Rd. 88 just south of Dinuba.
California Highway Patrol reported a downed tree branch from dust storm wind gusts blocking the Ellington St. off ramp on State Route 99 in Delano.
California Highway Patrol reported a tree blocking the roadway on Pacheco Rd. near South Union Ave. downed by dust storm winds in Bakersfield.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, September 2017
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: 720446, 720423, 720399, 720405, 720408, 720409, 720424, 720427, 720410, 720411, 720417, 720419, 720429, 720421, 720422, 720432, 720436, 720437, 720438, 720431, 720439, 720441, 720442, 720443, 720444, 720445.