Storms Sweeping Bay Area This Week to Bring Rain and Thunderstorms

After a streak of sunshine, forecasters said storms are likely to bring rain, potential thunderstorms, lightning and hail to the Bay Area this week, with some snowfall in the Sierra Nevada.

Thursday will remain mostly dry, but overcast with “a little more shower activity” across the North Bay, which indicates a low-pressure system is brewing, said Dylan Flynn, a meteorologist with the National Weather Service’s Bay Area office.

Friday is when the potential for rain and thunderstorms kicks up across the Bay Area, as the storm drifts over the Pacific Ocean toward the state. Flynn said the slow, erratic storm will hit the coast Friday, but it’s hard to say exactly where it will make landfall.

“It could be in San Luis Obispo, or it could be in downtown San Francisco, but someone’s going to be in the center of it. I just can’t say who,” Flynn said.

He said to expect widespread showers across the region “before the sun comes up” on Friday, with a 20%-30% chance of thunderstorms throughout the day. Flynn said to expect more rain and thunderstorms on Saturday, as the jet stream delivers a storm from the Gulf of Alaska into the region, colliding with Friday’s rain.

“It’s going to be heavy at times, but you might only get rain for 15 minutes and then three hours of dry conditions,” Flynn said. “Know how to protect yourself. When thunder roars, go indoors.”

Depending on where the storms make landfall, Nicole Sarment wrote in the region’s daily forecast discussion that thunderstorm hazards could include “lightning, locally heavy rainfall, erratic/gusty winds, and small hail.” She also wrote that localized flooding is possible.

“Even if we don’t get thunderstorms, we’re going to have widespread rain showers through most of the day, again, peaking in the afternoon,” Flynn said.

The first storm will be too warm to accumulate any new snow in the Sierras, but the second storm could drop some powder later this weekend, said Daniel Swain, a climate scientist with UC Agriculture and Natural Resources.

“We will continue to see snow melt over the next three days before potentially seeing some snow accumulation later on Saturday into Sunday,” Swain said during his YouTube office hours on Wednesday.

He said snow levels will likely “fall down to at least 5,000 feet,” which could include all of the passes and Lake Tahoe. The National Weather Service’s Sacramento office wrote in its daily forecast discussion on Wednesday that up to 2 feet of snow could fall above 4,500 feet, with up to 4 feet over the highest peaks. The service issued a winter storm watch for the southern Cascades and Northern Sierra above 4,500 feet from 5 p.m. Friday through 11 p.m. Sunday.

Flynn said Sunday looks like it’ll be a transition day with scattered showers before returning to normal springtime weather by Monday. Next week’s weather, Flynn said, is a little up in the air, and there’s a nearly even chance for potential sunshine or rain.