Skies cleared out in the San Joaquin Valley during the afternoon of December 21 from Fresno southward allowing for areas of fog to form during the evening as wind remained light. Some area of dense fog were noted along the SR 99 corridor in Tulare and Kern Counties.
Every event with a place to put it; 4 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.
Skies cleared out in the San Joaquin Valley during the afternoon of December 21 from Fresno southward allowing for areas of fog to form during the evening as wind remained light. Some area of dense fog were noted along the SR 99 corridor in Tulare and Kern Counties. An incoming storm allowed for some mixing to take place overnight which resulted in the fog layer lifting into a low cloud deck and improving visibility in the south valley.
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 Dec 21, 3:12 PM PST, 6 hours 53 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 312 PM PST Tue Dec 21 2021 .UPDATE...Updated air quality issues section. && .SYNOPSIS... An extended period of unsettled weather will begin late tonight and continue through the Christmas holiday weekend. Light to moderate precipitation will start to spread in from the north overnight and through Wednesday. Periods of moderate to occasionally heavy rain and mountain snow will occur Wednesday night through Thursday night. There may be a lull on Friday before more precipitation moves in for the Christmas weekend with snow levels lowering to around the major pass levels in Kern County. && .DISCUSSION... Similar to yesterday, a large deck of stratus clouds has persisted across much of the San Joaquin Valley today. But visible satellite loops show clearing occurring in the south end of the valley in the last hour. North of Kern County, there are signs of thinning clouds as the deck is fairly shallow at around 1000 feet thick. The stratus deck has kept things rather chilly with temperatures across the SJ Valley mainly in the lower 40s this early afternoon. Depending on the amount of clearing, temperatures may reach the lower to mid 50s in some locations later this afternoon as they should jump up fairly quickly. A big pattern change will begin tonight as the first in a series of disturbances begins to impact the central California interior. Low pressure off the Pacific Northwest coast will steer a moist southwest flow towards the SF Bay area tonight. Precipitation is expected to move in after midnight and mainly affect areas north of Fresno County through sunrise. Precip spreads south through the day but will likely remain north of Kern County until sunset. A Winter Weather Advisory is in effect for the Sierra Nevada from Yosemite NP to Sequoia NP from 10 PM tonight through 4 PM Wednesday. Snow levels will start out around 5000 feet overnight but due to the warm southwest flow will rise to 8000 feet Wednesday afternoon. Snow amounts of 6 to 12 inches are possible with the highest amounts around Yosemite NP and lowest amounts around Sequoia NP. Rainfall in the foothills and below the snow level in the Sierra through Wednesday afternoon will generally range from a quarter to 1 inch. Rainfall in the SJ Valley is expected to range from a few hundredths to a quarter of an inch with the higher amounts likely across Merced and Mariposa Counties. More widespread and heavier rain and snow will move in Wednesday night through Thursday and likely into Friday morning. There may be a lull in activity on Friday before additional disturbances bring periods of light to moderate showers through the Christmas weekend and into early next week. A Winter Storm Warning is in effect for the Sierra Nevada from Yosemite NP to just north of Lake Isabella from 4 PM Wednesday through 4 PM Sunday. Snow levels will lower to 7000-8000 feet Thursday, 5000-6000 feet on Friday, 3000-5000 feet on Saturday, then 3000-4000 feet Sunday. Forecast snow accumulations for the Winter Storm Warning area range from 1 to 5 feet with localized accumulations up to 8 feet possible over high elevations. Hazardous travel conditions are likely through and holiday weekend and accumulating snowfall could begin to affect the major pass levels in Kern County as early as Friday night. Forecast rain amounts across the SJ Valley generally range from 3/4" to 1.5". But rain shadowing should limit amounts for some locations along the west side and southern end of the valley. && .AVIATION... Widespread MVFR and local IFR visibilities and ceilings in mist/haze and stratus across the San Joaquin Valley through 06z Wednesday. Precipitation spreading in from the north after 06z with areas MVFR and local mountain obscuring IFR conditions across the Sierra Nevada. Otherwise, VFR conditions will prevail across the central CA interior for the next 24 hours. && .AIR QUALITY ISSUES... On Wednesday December 22 2021... Unhealthy for sensitive groups in Kern County. Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno...Kings...Madera...Merced and Tulare Counties. No Burning for All in Kern County. 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.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 4 PM Wednesday to 4 PM PST Sunday for CAZ323-326>331. Winter Weather Advisory from 10 PM this evening to 4 PM PST Wednesday for CAZ323-326>330. && Public/Aviation/Fire Weather...DCH PIO/DSS........................Dudley weather.gov/hanford
The national radar mosaic for the moment the first event began.
4 dense fog. Local standard time, as filed.
Visibility below a quarter mile was reported in Hanford.
Visibility below a quarter mile was reported in Delano.
Visibility below a quarter mile was reported in Bakersfield.
Visibility below a quarter mile was reported in Porterville.
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, December 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: 989960, 989959, 989962, 989961.