An upper level low dropped slowly southward off the California coast on between December 19 and December 21. Moisture associated with this feature produced widespread precipitation across our area between the evening of December 19 and the morning of December 21 with most of the precipitation occurring during the afternoon and evening of December 20.
Every event with a place to put it; 6 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 level low dropped slowly southward off the California coast on between December 19 and December 21. Moisture associated with this feature produced widespread precipitation across our area between the evening of December 19 and the morning of December 21 with most of the precipitation occurring during the afternoon and evening of December 20. Much of the San Joaquin Valley and the Kern County Mountains and Deserts picked up between a half inch and an inch of rainfall while the West Side Hills picked up between an inch and an inch and a half. While amounts in the Sierra Nevada and adjacent foothills varied, many locations picked up between a half inch and an inch of liquid precipitation. Several SNOTEL stations above 8000 feet picked up an estimated 3 to 8 inches of new snowfall while 1 to 3 inches of new snow accumulated between 7000 and 8000 feet. Elevations below 7000 feet generally picked up all rain.
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 19, 2:28 PM PST, 2 hours 35 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Hanford CA 228 PM PST Tue Dec 19 2023 .SYNOPSIS... A passing low pressure system will continue to create unsettled conditions into Friday, with areas of rain, and significant mountain snow above around 7000 feet. A few thunderstorms will also be possible through Thursday, but severe thunderstorms are not expected. Dry and seasonably cool conditions return for the holiday weekend. && .KEY MESSAGES... 1) Winter Storm Warning for elevations above 8000 feet through 10 AM PST Thursday morning. 2) Periods of precipitation expected through Thursday with heavier snow above 8000 feet. 3) General thunderstorm risk through Thursday. Severe thunderstorms are not expected. 4) Gusty winds from the southeast Wednesday afternoon and evening, especially through the Kern County mountains into the south end of the San Joaquin Valley. 4) Dry and seasonably cool weather will return by the weekend. && .DISCUSSION... A Pacific low pressure system continues to drop southeast well off the coast of northern California. Clouds and bands of mainly light to moderate showers are streaming northeastward across our area out ahead of the approaching system. Northern portions of our Valley zones have seen rainfall amounts around 1/4 to 1/2 inch so far, with around 3/4 of an inch in higher terrain below the snow line at around seven to eight thousand feet. Several inches of snow have accumulated at the higher elevations of the Sierra. Rainfall measurements taper to just a few hundredths of an inch in the south end of the Valley and little to none in the desert zones. The low pressure system is progged to continue dropping southeast before swinging inland near northern Baja by Friday. This will bring continued periods of precipitation to most of our area, with heaviest amounts occurring later Wednesday and Thursday over southwest portions as a better moisture fetch is streamed into our region. There is a 90 percent probability that total snowfall accumulations at the highest elevations will be at least 8 to 12 inches. One to two feet are forecasted, but there is a 1 in 10 chance that amounts could approach 3 feet. A Winter Storm Warning for the Sierra from Yosemite through Kings Canyon and Sequoia National Parks above 8000 feet remains in effect through 10 AM Thursday. The total rainfall amounts by the time the system has moved beyond our area are expected to be around one inch in the San Joaquin Valley and around one and one half inches in the higher terrain below the snow level. As the moisture stream is steered northeast across the region, there is as much as 5 to 15 percent probabilities for excessive rainfall over south and west portions of central California later Wednesday and Thursday, including portions of the South Valley and the Kern County mountain and desert zones. Southerly flow with the incoming low pressure system will produce gusty southeast winds Wednesday afternoon and evening, with moderate to strong gusts through the Kern County mountains and into the south end of the Valley. Probabilities for wind gusts of at least 30 mph are around 50 to 70 percent in the south end of the Valley by Wednesday afternoon. This could be accompanied by some blowing dust before enough precipitation moves in to wet the ground sufficiently. Conditions dry out and turn seasonably cool for the holiday weekend under weak ridging behind the exiting system. There will also be a potential for overnight and morning fog development in the San Joaquin Valley during this period. && .AVIATION... MVFR to IFR conditions along with local mountain obscurations are likely in and near showers through at least Wednesday. Otherwise, VFR conditions will prevail throughout the Central California interior over the next 24 hours. && .AIR QUALITY ISSUES... On Tuesday December 19 2023, Unhealthy in Kern County. Unhealthy for Sensitive Groups in Fresno, Kings, Madera, Merced, and Tulare Counties. Fireplace/Wood Stove Burning Status is: No Burning For All in Fresno, Kern, and Madera Counties. No Burning Unless Registered in Kings, Merced, and Tulare Counties. Burning Discouraged in Kern (Greater Frazier Park Area) and Sequoia National Park and Forest. && .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 and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 10 AM PST Thursday for CAZ323-326>328- 330. && public...JEB aviation....JEB weather.gov/hanford
The national radar mosaic for the moment the first event began.
6 flood, 6 winter weather. Local standard time, as filed.
An NWS employee reported roadway flooding at the intersection of Lacey Blvd. and Santa Fe Ave. in Hanford.
California Highway Patrol reported several rocks blocking one lane of SR 198 5SW Coalinga.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
Several higher elevation SNOTEL stations picked up an estimated 3 to 8 inches of new snowfall.
California Highway Patrol reported roadway flooding on SR 43 near the intersection of Iona Ave.
California Highway Patrol reported roadway flooding at the intersection of SR 33 and Lerdo Hwy.
California Highway Patrol reported the middle lanes of SR 99 were flooded at the Houghton Rd. offramp.
California Highway Patrol reported roadway flooding at the intersection of SR 166 and Old River Rd.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2023Every state in 2023This day in weather historyWarnings in California, December 2023
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: 1145340, 1145341, 1145346, 1145347, 1145348, 1145349, 1145350, 1145351, 1145342, 1145343, 1145344, 1145345.