West Coast slammed by record-breaking bomb cyclone

·7 min read

The last installment of a parade of storms barreled into the West Coast on Sunday, unloading more heavy rain that resulted in serious flooding and debris flows across drought-stricken and wildfire-ravaged California and even breaking some all-time 24-hour precipitation records.

The storm was the last in a train of storms from the Pacific Ocean that, along with an atmospheric river of moisture, had been impacting areas from British Columbia, Canada, to parts of Southern California since the middle of last week.

The heavy rain triggered flooding, which resulted in a number of high-water rescues, and slick driving conditions contributed to traffic accidents across the San Francisco Bay Area. The Associated Press reported that state highways 16 and 20 in Colusa and Yolo counties were shut down due to mudslides while evacuations were ordered in the Santa Cruz Mountains south of San Francisco. Officials were reportedly concerned that the rain could trigger debris flows in the burn scar area of the CZU Lightning Complex Fire which ignited in August 2020.

Flooding and debris flows were reported near the site of the Creek Fire, which scorched nearly 380,000 acres in Fresno County in 2020. Heavy rain also triggered evacuation orders for residents in Santa Barbara County living near the Alisal Fire burn scar.

In addition to being disruptive, the torrential rainfall was nothing short of record-breaking.

Downtown San Francisco recorded 4.02 inches of rain, making it the wettest October day on record for the city. That staggering rainfall total also reached into the top-five wettest days on record in San Francisco, with records going back to the Gold Rush era, the National Weather Service said. Sunday's total was the fourth-highest ever recorded there.

In downtown Sacramento, a 24-hour rainfall record was shattered. Sacramento measured 5.44 inches of rain as of early Monday, topping the previous 24-hour record of 5.28 inches that had stood since 1880. The nearby Sacramento Executive Airport tallied 5.41 inches of rain, topping the old 24-hour record of 3.77 inches from 1962. Those 5.41 inches account for nearly 82% of the water year's total rainfall.

The Sacramento deluge comes on the heels of a devastating dry spell the capital city endured. From late March to mid-October, the city went 212 straight days without measurable rain, The Sacramento Bee reported.

About 100 miles northeast of Sacramento in Reno, Nevada, 2.59 inches of rain were recorded in 24 hours from Sunday morning to Monday morning, just short of the October record of 2.65 inches set in 2010, according to NWS.

On Monday, the rain records continued. In Nevada, the 1.03 inches of rain recorded at Reno-Taho International Airport Monday shattered the daily record set back in 1982. Reno also officially surpassed its October monthly rainfall with a total of 3.14 inches. In California, a rainfall recording of 1.54 inches at Paso Robles Airport Monday broke the previous daily record by 1.36 inches, while 1.28 inches of rain at Santa Maria Airport was nearly an inch more than the previous daily record on Oct. 25 from 1951.

The Reno Gazette Journal reported on Monday that the heavy rain has triggered rockfalls in local canyons and hazardous driving conditions on Interstate 80, while drivers traveling over Carson Pass and Mt. Rose Summit have been advised to find alternative routes due to the potentially snowy conditions.

Widespread rainfall amounts of 5 to 10 inches were recorded in the central part of the state, with 16.56 inches at Middle Peak and 10.56 inches at Blue Canyon, according to the NWS.

Officials in Ventura County reported an increase in traffic collisions on Monday amid the wet weather.

Power outages were a growing issue as storm impacts mounted across the Pacific Northwest. At one point Sunday afternoon, more than 160,000 customers in California were experiencing power outages amid the powerful storm, some 28,000 outages were reported in Oregon and 109,000 had power cut in Washington, according to PowerOutage.us. On Monday afternoon, the number of customers reporting outages in California declined to about 67,000. By Tuesday morning, roughly 33,000 customers in California were still without power.

AccuWeather National Reporter Bill Wadell was in San Rafael, just north of San Francisco, and witnessed about 2-3 feet of floodwater turn streets into rivers on Sunday. David Brown, a San Rafael resident, told Wadell that the water came up to his waist as he made his way through one part of town.

To add to the weather mayhem, a tornado warning was issued just west of Wasco, California, on Monday afternoon. This was the first tornado warning issued in California's San Joaquin Valley in 592 days.

Also in San Rafael, on the Richmond-San Rafael Bridge, a video shared by a driver on Sunday captured a terrifying moment when a semi-truck was nearly blown over by the intense winds. In the footage, the back set of tires on the large truck are completely buffeted by the intense winds rushing through the bridge.

The semi's trailer can be seen smashing onto a neighboring vehicle and eventually crashing into the opposite side of the bridge, completely blocking the lanes of traffic.

According to Kron4, this certainly wasn't the only instance of trucks suffering in the conditions. Multiple other tractor trailers toppled over on the same bridge, which occurred around the time when peak wind gusts were reaching 70 mph, according to the NWS.

Forecasters said this grand finale of the storm parade had undergone bombogenesis, or the process in which a storm system undergoes rapid strengthening in a 24-hour period. The storm's lowest pressure was 942 millibars, or 27.82 inches of mercury, which is lower pressure than some tropical cyclones in the Atlantic this hurricane season. The ferocious storm produced wave heights off the coast up to 40 feet, according to data from the Ocean Prediction Center.

On the other side of the country, a nor'easter also underwent bombogenesis days after the West Coast storm. On Tuesday, the nor'easter brought record-setting 24- hour rainfall totals and wind gusts upwards of 80 mph to parts of the Northeast and New England.

In California's Sierra Nevada, wind gusts reached well over 100 mph. Mammoth Mountain notched a top wind gust of 159 mph, Squaw Mountain reported a gust of 141 mph and Kirkwood Mountain had a gust of 112 mph on Sunday as the storm barreled through.

These higher elevations dealt with heavy precipitation, but in the form of snow, not rain, forecasters said.

At the Central Sierra Snow Lab, located at Donner Pass in the Sierra Nevada, footage shared on Twitter by UC Berkeley showed the heavy snow peacefully falling to the ground. Trees, structures and the entire landscape were covered in the wintry precipitation, as laboratory officials reported that over 26 inches have fallen since late Sunday night.

Mount Rose, Nevada, has been the snowiest spot with a yardstick not being long enough to measure the fresh snowfall. As of Tuesday morning, 42 inches of snow had accumulated.

Farther to the north, thousands were also without power in Oregon and Washington. The same storm was blamed for the deaths of at least two people in the Seattle area when a tree fell onto a car, the AP reported.

About 45 miles south of San Francisco, a driving rain impacted much of Sunday's NFL game between the Indianapolis Colts and the San Francisco 49ers at Levi's Stadium.

"It was wet - very wet," Colts quarterback Carson Wentz said in an interview posted on the team's website. "It was obviously a challenge. Something we talked about all week. Ball security was at a premium."

Just as the rain was tapering off late on Monday, part of California was rocked by a magnitude 4.7 earthquake, according to the USGS. The epicenter was along the coast near San Simeon, California, with light shaking felt all the way from San Francisco to Santa Barbara. Just moments later, a magnitude 3.6 earthquake shook the same area.

Correction: Reno is located to the northeast of Sacramento, not to the northwest as a previous version of this article stated.

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