An upper trough pushed through California between the evening of September 27 and the evening of September 28. A cold front assocaited with this trough brought a cooler airmass into the area along with increased pressure gradients which resulted in a period of gusty winds over the Kern County Mountains and Deserts.
Every event with a place to put it; 8 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 episode as NWS HNX wrote it up.
An upper trough pushed through California between the evening of September 27 and the evening of September 28. A cold front assocaited with this trough brought a cooler airmass into the area along with increased pressure gradients which resulted in a period of gusty winds over the Kern County Mountains and Deserts. Several stations measured gusts around 60 mph during this timeframe. The winds diminished by the morning of September 29 as the trough moved to the east of the area.
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 27, 3:41 PM PST, 3 hours 59 minutes earlier.
Area Forecast Discussion...CORRECTED National Weather Service Hanford CA 441 PM PDT Mon Sep 27 2021 Updated air quality section .SYNOPSIS... A trough of low pressure will move through the region tonight bringing gusty winds and cooler temperatures. High pressure will then build over the area with winds aloft and at the surface will shift to the east on Wednesday and Thursday with temperatures warming to above normal. && .DISCUSSION... Satellite imagery shows an incoming trough of low pressure now extending across northwest California. Surface observations show winds on the increase from the northwest with UC Merced gusting to 19 mph shortly before noon. Winds this afternoon will continue to slowly increase with high resolution models showing the strongest push of winds into the San Joaquin Valley arriving early this evening. Meanwhile as the surface pressure gradients increase over Kern County, winds over the windy Mojave Desert Slope zone (east of Tehachapi) will easily reach 45-50 mph in gusts and overnight gusts to over 60 mph are likely in this traditionally windy location. As the northwest winds reach the south end of the San Joaquin Valley and upslope into the Grapevine, Tehachapi and Frazier Mountain areas, clouds will form and drizzle or light rain will fall in favored locations. Expect this to continue through Tuesday before winds abate and begin to turn to an easterly direction effectively shutting down the upslope drizzle process by later in the day. Smoke from Sierra fires will be shunted well to the southeast tonight and Tuesday with the San Joaquin Valley getting a reprieve however the East Kern County area will likely get plenty of smoke aloft in the northwest flow. Smoke on Wednesday will again begin to push back east towards the San Joaquin Valley as easterly flow increases. East Kern will get a reprieve, SJV will go back into the smoke. As for temperatures, a cooler air arriving behind the trough will trend temperatures down about 10-15 degrees on Tuesday and with lighter winds overnight and into Wednesday morning, overnight lows will seem much more autumn-like area wide, but especially over the desert areas where some upper 40s are likely. A general warming trend will however commence on Wednesday and continue through Friday as ridging builds back into California. Heights reach maximum values on Friday and Saturday and highs will be once again well above normal for late September. Forecast models for next week depict an area of low pressure well off the coast out around 34N/130W and a high pressure area over Southern Oregon. This will keep the Central California Interior in a dry pattern with weak southeasterly winds aloft and continued temperatures will above normal as we head into the first week of October.&& .AVIATION... In the Sierra Nevada and Kern County mountains, areas of MVFR visibilities, with local mountain obscured IFR visibilities, are expected due to smoke and haze, especially near active wildfires, through at least the next 24 hours. Elsewhere, VFR conditions will prevail today and tonight. && .AIR QUALITY ISSUES... On Tuesday September 28 2021... Unhealthy for sensitive groups in Sequoia National Park and Forest. Further information is available at Valleyair.org && .CERTAINTY... The level of certainty for days 1 and 2 is high. 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.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 4 PM this afternoon to 8 AM PDT Tuesday for CAZ338. && public...Dudley aviation....Dudley weather.gov/hanford
The national radar mosaic for the moment the first event began.
8 high wind. Local standard time, as filed.
The Mojave Airport AWOS measured a peak wind gust of 58 mph.
The Southern California Edison station at Cache Creek measured a peak wind gust of 61 mph.
The Indian Wells Canyon RAWS measured a peak wind gust of 60 mph.
The Blue Max RAWS measured a peak wind gust of 61 mph.
The Brid Springs Pass RAWS measured a peak wind gust of 59 mph.
The Jawbone Canyon RAWS measured a peak wind gust of 61 mph.
The CHP station at Cache Creek measured a peak wind gust of 59 mph.
The Southern California Edison station at Little Oak Canyon measured a peak wind gust of 61 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, September 2021
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: 977222, 977225, 977228, 977229, 977230, 977233, 977234, 977235.