A strong atmospheric storm brought moderate to heavy rain and a period of strong winds New Years Eve into early New Years Day, along with heavy high-elevation Sierra snow. There were 3 fatalities reported due to drowning. Precipitation totals by 8 am (over 24 hours) were around 1 to 3 inches for the southern Sacramento and northern San Joaquin Valleys, 3 to 8 inches for the Motherlode foothills and Northern Sierra from around SR 70 southward, with widespread flooding in those areas. Rainfall further north was generally an inch or less. There was significant river flooding on the Cosumnes River in Sacramento County around Wilton, due to multiple levee breaks. The river reached flood stage on the morning of December 31, and stayed in flood stage past midnight and into January 1. The flooding resulted in the evacuation of Wilton as the river went out-of-bank, with area highways and roads being closed, including SR-99. Significant flooding occurred from Wilton downstream through Interstate 5. River flooding was also reported along the Mokelumne River near Benson's Ferry and Mormon Slough at Bellota. Flooding of streams, in low areas and from clogged storm drains also closed many other roads across Northern California, with several small communities being evacuated. These events occurred mainly on December 31st and were reported on that date. Heavy snow disrupted mountain travel, with a total of 20 to 40 inches of snow above 6000 feet by the morning of the 1st. There were multiple spinouts causing Interstate 80 to be shut down for 18 hours. Highway 50 was closed in El Dorado County due to a combination of flooding and snow. High winds gusting to 50-65 mph in the Central Valley caused large numbers of trees to fall, bringing widespread power failures across the area, with hundreds of thousands of customers impacted. Most of the strong winds occurred on New Years Eve, with the damage events being reported on December 31, 2022, but power outage issues continued for tens of thousands of customers into the new year. Many local roads were also closed to downed trees blocking them, as well as many trees were reported to have fallen on homes and automobiles.

Flash Flood in SACRAMENTO, CALIFORNIA
From 01-JAN-23 10:30:00 to 01-JAN-23 23:59:00 (PST-8)
Location: SLOUGH HOUSE
Flood cause: Dam / Levee Break
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

There was a male fatality due to drowning in a submerged car, confirmed by Cosumnes Fire Department near SR 99 and Dillard Rd. A levee breech on the Cosumnes River caused the flash flood. This was one of three drowning deaths reported from the flash flood event. The Cosumnes Fire Department said they rescued dozens of people in the area over the past 24 hours. A helicopter from Metro Fire also rescued several people in the area. SR 99 remained closed due to flooding on the roadway. Several vehicles are still stuck in the flood waters. Wilton firefighters responded to 25 vehicles stranded in flood water and half a dozen fallen power lines. They also cleared many downed trees from the roadways as they navigated around Wilton.

Flash Flood in SACRAMENTO, CALIFORNIA
From 01-JAN-23 01:00:00 to 01-JAN-23 23:59:00 (PST-8)
Location: MC CONNELL
Flood cause: Dam / Levee Break
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The California Highway Patrol on January 4 reported a fatality associated with the December 31 - January 1 flash flood due to levee breaks. A female body was found outside a vehicle near Dillard Road east of CA-99. This is one of three confirmed fatalities from this event.

Heavy Snow in WEST SLOPE NORTHERN SIERRA NEVADA, CALIFORNIA
From 01-JAN-23 00:00:00 to 01-JAN-23 07:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The warm and very moist storm brought heavy snow to high elevations of the northern Sierra, generally above 6,000 feet. Boreal Ski Resort measured 40 inches of new snow, Central Sierra Snow Lab measured 29.9 inches, Dodge Ridge Ski Resort measured 22, Kirkwood 34 inches, Sierra at Tahoe 36 inches, Sugar Bowl 34 inches. Winds in the mountains gust to 45 to 65 mph. Snow with the strong gusty winds brought whiteout conditions at times with extended closures at the Sierra passes. Multiple spinouts on Interstate 80 caused it to be shut down for 18 hours, reopening at 10 am PST on January 1. US Highway 50 was closed for several hours in El Dorado County due to a combination of flooding and snow.

Flash Flood in SACRAMENTO, CALIFORNIA
From 01-JAN-23 00:00:00 to 01-JAN-23 12:00:00 (PST-8)
Location: WILTON
Flood cause: Dam / Levee Break
Property damage: 134.00M
Crop damage: 0.00K
Reported by: Emergency Manager

The Cosumnes River rose rapidly due to very heavy rains and already elevated levels from previous storms. Sacramento County OES confirmed the levee along the Cosumnes River breached in three locations overnight, causing flash flooding in the surrounding areas from Rancho Murieta to Wilton. SR 99 between Dillard Rd and Grantline Rd was flooded with numerous vehicles stuck in flood waters, requiring water rescues and was closed around midnight due to flooding. Flooding continued well into January. Sacramento County issued an evacuation warning overnight for the Wilton area, changed to a shelter-in-place warning a couple of hours later due to unsafe travel conditions with surrounding flooded areas. There were an estimated 3,200 to 3,500 people in the impacted area. There were three drownings attributed to the flooding, each entered as an individual event.

Flash Flood in SACRAMENTO, CALIFORNIA
From 01-JAN-23 06:00:00 to 01-JAN-23 23:59:00 (PST-8)
Location: TWIN CITIES
Flood cause: Dam / Levee Break
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Sacramento County Sheriff confirmed a drowning on January 4 associated with the December 31 - January 1 flash flood event. A female body was found inside a vehicle. This was the third drowning associated with the event. This flooding was due to levee breaks on the Cosumnes River.