A large upper trough moved slowly through California on December 30 and 31. This system had a deep fetch of tropical moisture associated with it which resulted in a period of moderate to heavy precipitation along with widespread flooding across much of the area on December 31.
Every event with a place to put it; 3 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 large upper trough moved slowly through California on December 30 and 31. This system had a deep fetch of tropical moisture associated with it which resulted in a period of moderate to heavy precipitation along with widespread flooding across much of the area on December 31. Numerous reports of flooding and debris flows were reported by law enforcement with several roads being briefly closed as a result of flooding. The system also produced strong wind gusts across the area between the afternoon of December 30 and the morning of January 1 with several stations in the West Side Hills and Tehachapi Mountains reporting gusts exceeding 60 mph. Several stations in the Sierra Nevada below 7500 feet picked up between 4 and 7 inches of rainfall while the adjacent foothills picked up 2 to 4 inches of rainfall. Rain shadowing effects limited precipitation in the San Joaquin Valley to between half an inch and an inch of rain at most locations while many stations in the Tehachapi Mountains also picked up between half an inch and an inch of rain. Several higher elevations SNOTEL stations picked up 18 to 30 inches of new snowfall adding to the heavy snowpack which had already accumulated earlier in December.
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 31, 3:04 PM PST, 9 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Hanford CA 304 PM PST Sat Dec 31 2022 .UPDATE...Updated air quality issue section. && .SYNOPSIS... Atmospheric river continues to slowly push southward today bringing significant precipitation to central California and causing some flooding incidents. Additional mainly light precipitation is expected Sunday through Tuesday, before another atmospheric river may impact Central California Wednesday and Thursday. && .DISCUSSION... Our anticipated atmospheric river event is underway and steady moderate to heavy rain continues to sag southward into central California. Areas of mainly nuisance flooding have been reported in Merced and Mariposa Counties this morning, but some incidents of more significant flooding have also occurred. Several Flood Advisories have been issued and the Flood Watch remains in effect through 4 am Sunday for most of our area below the snow line. High resolution short term models push the rain band southward through the day and into the evening, and the heaviest rain is progged to move south beyond Kern County by around midnight, with some lingering activity over the mountains into Sunday morning. Continued runoff is also pushing rivers and streams higher but representative forecast points are forecast to remain below flood stage. Snow levels currently running at or above 8000 ft will lower through the evening as the frontal band pushes southward. 2 to 4 feet of total snowfall accumulation is expected over the high Sierra and A Winter Storm Warning remains in effect there through early Sunday morning. A few inches of snow will accumulate in the highest elevations of the Kern County mountains but snow levels are not likely to reach pass levels there, as guidance shows a zero percent probability for one tenth of an inch of snow at Fort Tejon. Winds will continue to blow over the west side mountains and the Wind Advisory there has been extended through 10 PM. Gusty winds ahead of the approaching frontal system will also impact the desert areas and a Wind Advisory is in effect there through midnight tonight. The Mojave slopes will also experience significant wind gusts as the trough pushes through and a Wind Advisory will be in effect there this evening through Sunday afternoon. We will see a break from the precipitation Sunday but ensembles bring a less potent system through our area Monday followed by another stronger system Wednesday and Thursday which will be more similar to this current atmospheric river event. && .AVIATION...VFR/MVFR conditions will prevail for the next 24 hours. Areas of IFR/LIFR conditions in heavier showers and higher terrain possible through 12Z Sunday, with some lingering upslope clouds and showers through 18Z. && .AIR QUALITY ISSUES... On Sunday January 1 2023, Fireplace/Wood Stove Burning Status is: Burning Discouraged in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest. && .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 and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 10 PM this evening to 5 PM PST Sunday for CAZ338. Flood Watch through late tonight for CAZ300>322-324-325. Wind Advisory until 10 PM PST this evening for CAZ300-308-313. Winter Storm Warning until 4 AM PST Sunday for CAZ323-326>331. Wind Advisory until midnight PST tonight for CAZ337-339. && public...JEB aviation....AS weather.gov/hanford
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1018 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1018 PM FLOOD 3 SW SPRINGVILLE 36.10N 118.86W
12/31/2022 TULARE CA LAW ENFORCEMENT
LARGE ROCK ON THE ROADWAY.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1026 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1024 PM FLOOD 6 WSW FISH CAMP 37.43N 119.73W
12/31/2022 MARIPOSA CA LAW ENFORCEMENT
TREES BLOCKING BOTH LATES.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1030 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1027 PM FLOOD 9 ENE CLOVIS 36.87N 119.56W
12/31/2022 FRESNO CA LAW ENFORCEMENT
BOTH LANES ARE FLOODED ON SR 168.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1103 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1057 PM FLOOD 5 E AUBERRY 37.07N 119.40W
12/31/2022 FRESNO CA LAW ENFORCEMENT
ROCKS ON AUBERRY RD AT ALTER SPRINGS RD
INTERSECTION. ROAD STILL PASSABLE.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1116 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1109 PM DEBRIS FLOW 5 WNW SQUAW VALLEY 36.73N 119.27W
12/31/2022 FRESNO CA LAW ENFORCEMENT
MUD AND ROCKS COVERING 75 % OF RDWY.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HANFORD CA
1119 PM PST SAT DEC 31 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1116 PM DEBRIS FLOW 1 S MIDPINES 37.52N 119.92W
12/31/2022 MARIPOSA CA PUBLIC
LARGE MUDSLIDE BLOCKING HALF OF WB LANES ON
SR 140.
&&The national radar mosaic for the moment the first event began.
9 flood, 3 debris flow, 2 high wind, 1 strong wind. Local standard time, as filed.
California Highway Patrol reported closing the mouth of Kern Canyon with two sections of large boulders blocking the eastbound lanes of SR 178 near NM 17 and NM 21.
California Highway Patrol reported a few feet of mud on part of SR 41 near Tenaya Lodge in Oakhurst.
California Highway Patrol reported a large tree blown over onto the roadway in Dos Palos.
California Highway Patrol reported rocks washed up on the roadway at the intersection of N. Piedra Rd. and Elwood Rd.
US Military Police reported roadway flooding at the intersection of S. Dickenson Ave. and W. Oakland Ave. at Lemoore Naval Air Station.
California Highway Patrol reported rocks washed up on the road at the intersection of SR 198 and SR 216 in Lemoncove.
The Southern California Edison station at Cottonwood Creek measured a peak wind gust of 71 mph.
California Highway Patrol reported a tree washed up on the roadway on SR 168.
California Highway Patrol reported a tree blocking the roadway on Rd. 426 near Rd. 222. at Bass Lake.
California Highway Patrol reported roadway flooding at the intersection of SR 59 and McNamara Rd.
The Jawbone Canyon RAWS measured a peak wind gust of 77 mph.
California Highway Patrol reported a tree blocking part of the intersection of SR 168 and Tollhouse Rd.
California Highway Patrol reported a large boulder blocking both lanes of Jose Basin Rd. near the intersection with Sugarloaf Rd.
California Highway Patrol reported roadway flooding on Buchanan Hallow Rd. south of LeGrand.
California Highway Patrol reported water from a canal flooding onto the roadway south of Merced.
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, January 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 2026-09-30. Each event’s entry at NCEI: 1062433, 1062434, 1062435, 1062441, 1062446, 1062448, 1062436, 1062450, 1062457, 1062458, 1062438, 1062461, 1062463, 1062459, 1062460.