A deep upper low pressure system dropped from the Pacific Northwest into the Great Basin during the morning of October 11. This resulted in a period of strong winds from the late morning hours until the evening as a very strong pressure gradient developed.
Every event with a place to put it; 19 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.
A deep upper low pressure system dropped from the Pacific Northwest into the Great Basin during the morning of October 11. This resulted in a period of strong winds from the late morning hours until the evening as a very strong pressure gradient developed. Several stations reported wind gusts exceeding 58 mph with the strongest winds most noticeable on the Mojave Desert Slopes of the Tehachapi Mountains. A few low impact indicator sites reported gusts exceeding 80 mph. The winds diminished by the morning of October 12 as the low moved east of the Great Basin and pressure gradients relaxed.
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 Oct 11, 4:15 AM PST, 4 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 515 AM PDT Mon Oct 11 2021 .SYNOPSIS... A low pressure system will bring windy and unseasonably cool conditions today into Tuesday. Scattered showers will be possible over the Sierra with dry and windy conditions elsewhere across central California. High pressure will bring a warming trend to the area along with decreased winds from Wednesday through Friday. && .DISCUSSION... The well advertised windy and colder system will continue to move into the region today and with it bring increased winds to the area. Current satellite imagery shows the trough moving southward through northern California and entering central California. Generally the strongest winds today will be in the Kern County Mountains and into the Kern Desert areas, of course the wind prone localities like through and below the mountain passes will have the greatest chance of strong winds. This included Grapevine, Tehachapi, and Walker Passes. Today there is a 98 percent chance of wind gusts over 35 mph for Tehachapi and the Grapevine area. For out in the desert Edwards will see a 79 percent chance of 35 mph or greater winds. While in Mojave there is a 92 percent chance of that occurrence. A High Wind Warning is in effect from 8 AM until 11 PM tonight to address this strong wind threat. Blowing sand and dust will be likely at times especially with the strongest gusts. So use caution when driving for sudden drops in visibilities but high profile vehicles are also susceptible to be blown over or off the roads in the cross winds on North to South orientated roads. Now these areas will not be the only place to get a taste of the winds as even the coastal hills and the central/western San Joaquin Valley will see gusty winds, although not as strong as the previous mentioned locations, however with many fallow fields blowing dust will also be a good bet with the gusty winds and again caution is advised while driving as lowered visibilities in the strongest gusts may make driving dangerous. So be cautious when driving in the winds out there folks. A Wind Advisory is in effect for the western parts of the SJV and coastal hills from 8 AM this morning until 11 PM tonight. A Red Flag Warning is also in effect for those same times in the west side hills and far western SJV due to the gusty winds and obviously dry fuels from the lack of rainfall. This system is much drier than the last system from late last week but there still will be a possibility for light showers in the higher elevations and even light snow mainly above 5500 feet however some snow showers will be possible later this afternoon and evening down to around 4000 feet but will be very light as the precipitation winds down as the coldest air moves into the region. A trace to around a half on an inch of snowfall will be the the outcome for most locations that receive any snow but localized amounts up to 4 inches for the highest elevations. Now the main precipitation will unfortunately only be from Tulare County northward as areas south of this will be snubbed, however a few locations such as near Pine Mountain Club and Frazier Park could possibly see some showers but whatever does fall will be light. Low temperatures will be on the cold side overnight tonight especially in the higher elevations but even in the SJV lows in the lower 40s will be possible in a few locations, out in the Kern desert areas mid 30s will occur. A few localized spots in the desert could approach the freezing mark so out of precaution it would be best to bring in or protect frost sensitive plants. Temperatures over the next several days begin to trend warmer but with current normal high temperatures for Fresno of 81 and 83 for Bako, temperatures will remain cooler than normal at least through Friday as high pressure ridging begins to move in. Stronger ridging will move into the region this weekend and temperatures over the weekend will again be right around normals. && .AVIATION... Scattered mainly light showers will develop over the Sierra Nevada after 16Z Monday. Expect strong gusty northwesterly winds over 35 knots developing across the region Monday morning by 18Z and continuing through 00Z Tuesday. Otherwise, mainly VFR conditions can be expected for the next 24 hours. && .AIR QUALITY ISSUES... On Monday October 11 2021... Unhealthy for sensitive groups in Kern and Kings Counties. 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... High Wind Warning from 8 AM this morning to 11 PM PDT this evening for CAZ331>339. Wind Advisory from 8 AM this morning to 11 PM PDT this evening for CAZ300>316-332>334-336. Red Flag Warning from 8 AM this morning to 11 PM PDT this evening for CAZ579-580. && public...Andersen aviation....Bollenbacher idss/PIO...Bollenbacher weather.gov/hanford
The national radar mosaic for the moment the first event began.
19 high wind. Local standard time, as filed.
The Southern California Edison station 9E Lebec measured a peak wind gust of 70 mph.
The Blue Max RAWS measured a peak wind gust of 69 mph.
The Southern California Edison station at Grapevine Canyon Road measured a peak wind gust of 73 mph.
The Indian Wells Canyon RAWS measured a peak wind gust of 102 mph.
Jawbone Station measured a peak wind gust of 61 mph.
The Southern California Edison station at Little Oak Canyon measured a peak wind gust of 73 mph.
The Cache Creek CHP station measured a peak wind gust of 59 mph.
The Southern California Edison station at Cache Creek measured a peak wind gust of 69 mph.
The Jawbone Canyon RAWS measured a peak wind gust of 83 mph.
The Bird Springs Pass RAWS measured a peak wind gust of 87 mph.
The Southern California Edison station at Tehachapi East Valley measured a peak wind gust of 58 mph.
The Southern California Edison Station at Mountain Mesa measured a peak wind gust of 58 mph.
The Walker Pass RAWS measured a peak wind gust of 69 mph.
The Bear Peak RAWS measured a peak wind gust of 67 mph.
The Mojave Airport AWOS measured a peak wind gust of 78 mph.
The PG&E station 2W Lebec measured a peak wind gust of 58 mph.
The Kettleman Hills RAWS measured a peak wind gust of 61 mph.
The Southern California Edison station 5E Lebec measured a peak wind gust of 59 mph.
The Laural Mountain RAWS measured a peak wind gust of 63 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, October 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: 979101, 979096, 979094, 979085, 979121, 979090, 979124, 979097, 979074, 979076, 979075, 979127, 979080, 979082, 979088, 979130, 979131, 979123, 979129.