First of several storms arrives in Bay Area, starting off rainy week

Clouds were growing darker across the Bay Area on Sunday morning as the first of three back-to-back rain storms landed in the region, which are expected to bring several inches of rain from San Jose to the North Bay in rainy days that could last through next Sunday.

The rainfall was expected to intensify in the late afternoon Sunday and into the night as the first storm arrives from the Gulf of Alaska, said Roger Gass, a meteorologist with the National Weather Service.

“The initial storm system is off the coast, and it’s potentially going to remain off the coast and not actually have a frontal passage with it, but we are expecting additional storm systems on Tuesday and Wednesday to bring high elevation snowfall to the region,” Gass said. “We continue to have chances for rain through next Sunday, so it’s an overall decently wet pattern.”

Inland, a snowstorm is also bringing several feet of snow to Lake Tahoe.

The first Bay Area storm, which is forecast to last through Monday evening, will bring about 1 to 2 inches of rain across the region, with some higher elevation areas such as the Santa Cruz Mountains expected to receive upwards of 4 inches, Gass said. San Jose, Concord and San Francisco will see between 1½ and 2 inches of precipitation. Oakland will see up to 1¾ to 2¾ inches.

The heaviest rainfall in the first system is projected to come through the region over Sunday night into Monday, Gass added.

“The subsequent systems are a little bit less rainfall, but maybe some stronger winds with the Monday night into Tuesday system,” Gass said.

Those winds are forecast to range from 35 to 45 miles per hour, with higher elevations potentially seeing speeds up to 55 miles per hour, he said.

The first storm system will bring with it high temperatures ranging from the mid-50s to low 60s across the region Sunday, which will then remain in the mid-50s Monday, Gass added. As the week goes on, temperatures will cool as a colder mass of air arrives in the region, bringing temperatures down to the high 40s to low 50s on Tuesday through Thursday.

Unlike many atmospheric rivers that come through the Bay Area, which tend to leave cities such as San Jose in a rain shadow, this storm will not be blocked by mountains, resulting in more rainfall in the Santa Clara Valley.

“When the showers move over any given area, it’s not like the mountains are blocking the atmospheric rivers that typically cause that reduced amount of rainfall in the rain shadow valleys,” Gass said.

The North Bay will not be hit hardest as it is in many other storms, and is expected to receive between 1 and 1½ inches through Monday evening, Gass added.

The storms are not expected to bring any major flooding because they will bring more intermittent rain as opposed to continuous precipitation, Gass said, adding that drivers should remain cautious of any flooded roadways or downed power lines or trees — and “turn around, don’t drown.”

“As we always say, if there’s water covering the roadway, you don’t know how deep it is or if the roads underneath it have been washed out,” Gass said. “That is one of the leading causes of deaths in the United States.”

The NWS issued a winter storm warning lasting from Sunday night through Wednesday night for the greater Lake Tahoe area, with forecasts expecting snowfall between two and three feet in the Tahoe Basin and between three and five feet at elevations above 7,000 feet, according to the warning. Winds may reach 35 to 45 miles per hour, with gusts on the Sierra ridge up to 100 miles per hour.

“Travel could be very difficult to impossible with periods of whiteout conditions. Very strong winds could cause damage to trees and power lines,” the NWS said. “If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency. The latest road conditions for the state you are calling from can be obtained by calling 5-1-1.”

The Lake Tahoe precipitation was expected to begin Sunday night, with a chance of rain and snow in the evening turning to a forecast of heavy snow in the early morning hours of Monday, according to a forecast from the NWS Reno Office. Snowfall is projected to be around 4 inches, with between 2 to 6 inches expected above 7,000 feet. Temperatures will dip to between 22 and 32 degrees.

The storm is forecast to bring heavy snow Monday and Tuesday, with 3 to 7 inches projected on Monday, according to the forecast. Snow chances remain through at least Friday.

The NWS also issued an avalanche watch lasting until Monday morning due to the storm, according to the alert. From Monday evening to Tuesday night or Wednesday, the backcountry was expected to see high avalanche danger.

“A powerful storm with rapidly accumulating snowfall and strong winds may cause widespread avalanche activity in the mountains,” NWS said. “Large avalanches capable of burying or injuring people could occur in backcountry areas.”

The rain will begin to taper off in the Bay Area around Thursday, but rain chances remain through next Sunday, Gass said.