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.

Flood in KERN, CALIFORNIA
From 01-JAN-23 00:09:00 to 01-JAN-23 03:09:00 (PST-8)
Location: DEMOCRAT SPGS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

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.

Debris Flow in MADERA, CALIFORNIA
From 01-JAN-23 00:16:00 to 01-JAN-23 03:16:00 (PST-8)
Location: NEW AUBERRY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a few feet of mud on part of SR 41 near Tenaya Lodge in Oakhurst.

Strong Wind in LOS BANOS-DOS PALOS, CALIFORNIA
From 01-JAN-23 00:35:00 to 01-JAN-23 00:35:00 (PST-8)
Magnitude: 35.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a large tree blown over onto the roadway in Dos Palos.

High Wind in TEHACHAPI, CALIFORNIA
From 01-JAN-23 04:00:00 to 01-JAN-23 04:00:00 (PST-8)
Magnitude: 62.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Utility Company

The Southern California Edison station at Cottonwood Creek measured a peak wind gust of 71 mph.

High Wind in TEHACHAPI, CALIFORNIA
From 01-JAN-23 06:14:00 to 01-JAN-23 06:14:00 (PST-8)
Magnitude: 67.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

The Jawbone Canyon RAWS measured a peak wind gust of 77 mph.

Flood in FRESNO, CALIFORNIA
From 01-JAN-23 00:43:00 to 01-JAN-23 03:43:00 (PST-8)
Location: PIEDRA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported rocks washed up on the roadway at the intersection of N. Piedra Rd. and Elwood Rd.

Flood in FRESNO, CALIFORNIA
From 01-JAN-23 03:01:00 to 01-JAN-23 06:01:00 (PST-8)
Location: SHILLING
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

US Military Police reported roadway flooding at the intersection of S. Dickenson Ave. and W. Oakland Ave. at Lemoore Naval Air Station.

Flood in TULARE, CALIFORNIA
From 01-JAN-23 03:17:00 to 01-JAN-23 06:17:00 (PST-8)
Location: LEMONCOVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported rocks washed up on the road at the intersection of SR 198 and SR 216 in Lemoncove.

Flood in FRESNO, CALIFORNIA
From 01-JAN-23 04:27:00 to 01-JAN-23 07:27:00 (PST-8)
Location: INDIAN MISSION
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a tree washed up on the roadway on SR 168.

Flood in MADERA, CALIFORNIA
From 01-JAN-23 05:12:00 to 01-JAN-23 08:12:00 (PST-8)
Location: THE PINES
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a tree blocking the roadway on Rd. 426 near Rd. 222. at Bass Lake.

Flood in MERCED, CALIFORNIA
From 01-JAN-23 05:12:00 to 01-JAN-23 08:12:00 (PST-8)
Location: MERCED ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported roadway flooding at the intersection of SR 59 and McNamara Rd.

Flood in MERCED, CALIFORNIA
From 01-JAN-23 10:16:00 to 01-JAN-23 13:16:00 (PST-8)
Location: LE GRAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported roadway flooding on Buchanan Hallow Rd. south of LeGrand.

Flood in MERCED, CALIFORNIA
From 01-JAN-23 10:40:00 to 01-JAN-23 13:40:00 (PST-8)
Location: (MER)CASTLE AFB
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported water from a canal flooding onto the roadway south of Merced.

Debris Flow in FRESNO, CALIFORNIA
From 01-JAN-23 07:17:00 to 01-JAN-23 10:17:00 (PST-8)
Location: INDIAN MISSION
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a tree blocking part of the intersection of SR 168 and Tollhouse Rd.

Debris Flow in FRESNO, CALIFORNIA
From 01-JAN-23 09:47:00 to 01-JAN-23 12:47:00 (PST-8)
Location: CHAWANAKEE NO 2
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

California Highway Patrol reported a large boulder blocking both lanes of Jose Basin Rd. near the intersection with Sugarloaf Rd.