Although a weak cold frontal passage occurred over central California on November 23, the lower levels remained very stable and skies cleared out during the evening. With clear skies prevailing overnight and light winds prevailing in the San Joaquin Valley, areas of dense fog formed in the center of the valley.
Every event with a place to put it; 5 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.
Although a weak cold frontal passage occurred over central California on November 23, the lower levels remained very stable and skies cleared out during the evening. With clear skies prevailing overnight and light winds prevailing in the San Joaquin Valley, areas of dense fog formed in the center of the valley. The fog dissipated by late morning. Dense fog also was present in the Tehachapi area during the morning commute period as a result of low level upslope flow; however, the fog lifted out by late morning.
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 Nov 23, 4:35 PM PST, 7 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 435 PM PST Tue Nov 23 2021 .UPDATE... Updated AIR QUALITY ISSUES section. && .SYNOPSIS... Dry weather will continue through the middle of next week. A low pressure system will produce cooler temperatures for the middle of this week. Moisture trapped in the San Joaquin Valley will continue to create episodes of nighttime and morning fog. && .DISCUSSION... While dense fog dominated the San Joaquin Valley’s weather this Tuesday, change in on the way as a cold front drops from the north. The Dense Fog Advisory was allowed to expire at noon today and will have a challenge if fog is able to form once again. As the cold front approaches the area, surface pressure gradients from KSFO to KLAS have already reached 6mb and is trending upward toward 7-9mb tonight into early Wednesday morning. Radar Wind profiler data is showing speeds of 10 to 20 mph just above the surface which supports the tightening gradient today. Furthermore, low level temperature data is also showing cold air pushing across California today as cold air advection is expected to influence the potential for fog development. At the present moment, will hold off on the issuance of another dense fog advisory as cold-dry invades to area in the short term. Afterward, fog may become a problem again as an area of high pressure attempts to remain anchored over the West Coast through the middle of next week. A cold front is progged to cut through the area today as cold and dry air filters into the region overnight and into Wednesday. While the combination of higher winds and cold-dry air may hinder the development of fog overnight, fog (patchy at best) may still for over the favored places. Yet, visibility values may only drop to a around a mile. Criteria will not be met for an advisory but will still require caution during the commute. By the same token, surface pressure gradients are not reaching beyond 10mb and the potential for a wind advisory across the Kern County Mountain (Tehachapi Pass) and into the Mojave Desert. Across that area, wind gusts could briefly reach 30 mph this evening with 15 to 20 mph gusts being more common through early Wednesday. One other note will be the placement of the coldest air along with the orientation of a jet max during the day on Wednesday. While the timing of the surface gradient and wind aloft support are not in- phase with time of day for the greatest potential for Mono-Type winds, northeast may develop Wednesday morning. When speeds do increase, the winds will have decoupled from the surface around the mid-day period. This timing will not favor strong northeast winds across the Sierra Nevada. After the passage of the disturbance, cold air will overtake the area as ensembles struggle to reach 60 degrees across the San Joaquin Valley on Wednesday afternoon. Probability of exceeding 60 degrees across San Joaquin Valley Wednesday afternoon remains below 50 percent. This increases confidence that cold air will make into the area as the Kern County Desert approaches near freezing values by Thursday morning. If confidence grows, will have to consider a statement for the cold overnight temperatures. At that point, the ridge pattern rebuilds and fog, along with cold temperatures will then become the dominating weather features for Central California. && .AVIATION... In the San Joaquin Valley, widespread MVFR visibility with patches of IFR visibility due to haze/mist. VFR conditions will prevail elsewhere across the Central CA Interior for the next 24 hours. && .AIR QUALITY ISSUES... On Wednesday November 24 2021... Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno... Kern... Madera and Tulare 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... None. && public...Molina aviation....DS weather.gov/hanford
The national radar mosaic for the moment the first event began.
5 dense fog. Local standard time, as filed.
Visibility below a quarter mile was reported in Merced and Madera. Several webcams showed visibility below 1000 feet.
Visibility below a quarter mile was reported in Hanford. Several webcams showed visibility below 1000 feet.
Visibility below a quarter mile was reported in Fresno. A trained spotter reported 200 foot visibility in Sanger.
Visibility below a quarter mile was reported in Visalia. Several webcams showed visibility below 1000 feet.
Visibility below a quarter mile was reported in Tehachapi.
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, November 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: 986889, 986891, 986890, 986892, 986893.