The atmospheric river that arrived on Wednesday doused the Bay Area with rain and caused flood and high wind warnings by Thursday morning.
The atmospheric river consisted of a strong upper level low and subtropical moisture top, National Weather Service meteorologist Rachel Kennedy said. A low pressure system that started in Northern California close to the California-Oregon border and cold front moved its way through the area through the central coast by Thursday morning, marking the end of the first round of rain. It lead to scattered showers late Thursday morning in some parts.
“The system is pretty deep and transporting a fair amount of moisture into our region, which is why we’re getting some pretty heavy rainfall with it,” Kennedy said.
From Thursday to early Friday morning, a majority of the Bay Area will have received one-half an inch to one inch of rain, with the highest rainfall totals in the elevated terrain of the Santa Cruz mountains and the Santa Clara hills. Kennedy expected that the North Bay mountains will get 1.5 to 2 inches of rain, while the Santa Cruz mountains and Santa Clara hills will see between 1.5 to 3 inches of rain for the rest of Thursday. She said it was possible for the Santa Lucia mountains to see up to 5 to 6 inches of rain.
The entire Bay Area is on a flood watch until 10 p.m. on Saturday. A high wind warning had been issued Wednesday along the coast of the North Bay and Peninsula into Friday morning. There was also a wind advisory issued on Wednesday across the inland Bay Area that will last until Friday morning.
Kennedy said that flood advisories are being issued as needed, but at one point, the entire Bay Area was impacted by flood concerns due to the first round of showers that moved in overnight Wednesday and the next round of showers moving in Thursday morning. She said a flash flood warning was issued overnight on Wednesday in the Santa Cruz mountains, but it was downgraded to a flood warning by Thursday morning.
In Gilroy, Silva’s Crossing at Miller Avenue and Uvas Parkway was closed Thursday morning due to flooding. Lamonte Toney, a spokesman for the Gilroy Police Department, said that flooding recurrently happens in that area whenever the city gets significant amount of rain. The canal that runs through that area has a water level of 189 feet, and when it rains and the water level rises above that number, the gates are closed, preventing drivers and pedestrians from using the crossing.
The Gilroy Fire Department will be monitoring water levels until it is safe to reopen. Toney said people should take Luchessa Avenue or Santa Teresa Boulevard to get to the residential neighborhoods and schools in that area to avoid the flooding.
“It’s hard to say (when the crossing will be reopened). It depends on how much rain we get,” Toney said.
In addition to rain, Lake Tahoe and the Sierra Nevada are seeing snow. NWS meteorologist Bill Rasch said there was a mix of rain and snow in South Lake Tahoe on Thursday. He forecast that between 1 to 3 inches of snow would accumulate during the day on Thursday while between 8 to 12 inches of snow would fall Thursday night. He said there would be between 1 to 3 inches of snow by Friday morning, totaling about 14 inches over the next day.
At peak level, there was between 2 to 4 feet of snow with snow levels rising by Thursday morning, Rasch. The snow level at 5,500 feet reached between 1 to 3 feet of snow and he forecast that the snowfall would pick up again Thursday afternoon. He advised anyone traveling across the Sierra Nevada to check road reports.
“it’s definitely going to be sketchy and it’s going to get worse this afternoon and this evening,” Rasch said.