A low pressure system dropped slowly southward along the California coast on December 29 and 30 resulting in much of the area picking up between a quarter to half an inch of liquid precipitation. The snow level varied during this event beginning at around 2000 feet during the morning of December 29, but quickly rising to around 5000 feet by the afternoon of December 29.
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.
A low pressure system dropped slowly southward along the California coast on December 29 and 30 resulting in much of the area picking up between a quarter to half an inch of liquid precipitation. The snow level varied during this event beginning at around 2000 feet during the morning of December 29, but quickly rising to around 5000 feet by the afternoon of December 29. Snow levels lowered overnight to around 4000 feet by the morning of December 30 resulting in accumulation snow on several roads in the Kern County Mountains. Interstate 5 was closed through Tejon Pass for a few hours as a result of snow fall disabling several vehicles trying to travel through the area. A surge of milder marine air pushed in over the Tehachapi Mountains during the afternoon of December 30 resulting in the snow turning to rain and temperatures rising well above the freezing mark. The precipitation ended by early evening as the slow moving low moved out 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 Dec 29, 2:31 AM PST, 4 hours 29 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 231 AM PST Wed Dec 29 2021 .SYNOPSIS... The last in a series of weather disturbances will move through the area today and tonight. Snow in the mountains and rain in the lower elevations will come to an end on Thursday morning as the system moves to the east. High pressure will then build over the region this weekend for a return to dry weather. && .DISCUSSION... Regional radars show the next area of precipitation now pushing into Merced, Madera and Western Fresno Counties. Echoes suggest only light precipitation is occuring and much could be aloft. Heavier precipitation is noted over the Bay Area and this will move southeast into the Central California Interior later today. Water vapor satellite imagery shows two distinct areas of spin or vorticity. The first is dropping down the Central Coast and causing the lighter echoes over the area while the second larger vorticity center is well northwest of San Francisco and is moving southward. High resolution forecast models bring the lighter band of precipitation into the Sierra through sunrise and then as the offshore low pressure area approaches the Central Coast later this morning, a secondary and larger area of rain and snow will move through the area. Forecast snowfall amounts in the Sierra will range up to 18 inches through today and tonight with models suggesting some isolated locations may see more accumulation. Overall amounts should easily reach Winter Weather Advisory levels and the current Advisory will remain in place. As for snow levels, the more maritime nature of this incoming system will actually act to raise snow levels from the current 2500-3500 feet to 4500-5500 feet by later this afternoon. This may mitigate the threat of snow on the Kern County mountain passes such as the Grapevine or Tehachapi Pass. As the precipitation will begin as snow on these heavily traveled passes, the Winter Weather Advisory will remain in place. It will remain to be seen if a changeover to rain at pass levels occurs or not. Models then drive the low southward overnight and this will bring the precipitation to an end from north to south with Kern County clearing out early Thursday morning. Models are in good agreement in bringing a change to drier weather as the overall upper air pattern shifts and a ridge of high pressure builds over the region. The ridge will remain in place into Monday then models bring another Pacific frontal system into Northern California. This system then is projected to move into Central California on Tuesday. All in all more welcome precipitation next 24 hours, a break to drier then maybe more wet weather early next week. && .AVIATION... MVFR with patches of IFR conditions are likely across the San Joaquin Valley and lower Sierra Foothills over the next 24 hours. Mountain obscuration with areas of IFR conditions are expected in the Sierra Nevada through for at least the next 24 hours. && .AIR QUALITY ISSUES... .none && .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 Weather Advisory until 10 AM PST Thursday for CAZ318-320- 322>336. && public...Dudley aviation....Dudley weather.gov/hanford
The national radar mosaic for the moment the first event began.
4 winter weather, 1 debris flow. Local standard time, as filed.
Several road closures were reported by California Highway Patrol and the California Department of Transportation. Several stations measured 2 to 5 inches of new snowfall above 4000 feet.
Several road closures were reported by California Highway Patrol and the California Department of Transportation. Several stations measured 2 to 5 inches of new snowfall above 4000 feet.
Several road closures were reported by California Highway Patrol and the California Department of Transportation. Several stations measured 2 to 5 inches of new snowfall above 4000 feet.
Several road closures were reported by California Highway Patrol and the California Department of Transportation. Several stations measured 2 to 5 inches of new snowfall above 4000 feet.
California Highway Patrol reported a large boulder on Old Kern River Canyon Rd.
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: 990794, 990795, 990796, 990797, 990793.