After nearly four weeks without rain, Californians are finally seeing precipitation return to the forecast. The wet pattern arriving this week comes in pieces, and the Bay Area should see significant rain from the final storm, while temperatures will remain cool.
California will get rain this week; storm outlook for SF, state
California Braces for Return of Rain After Prolonged Dry Spell
After nearly a month of unusually dry conditions, California is finally poised to receive much-needed precipitation. While the initial storms arriving this week will offer limited relief, a more substantial system is expected to bring significant rainfall to the Bay Area and a welcome boost of snow to the Sierra Nevada by the weekend.
A Parched State Finds Relief
The return of rain is a welcome sign for a state grappling with the ongoing impacts of climate change and the ever-present threat of drought. California has experienced increasingly erratic weather patterns in recent years, with prolonged periods of drought punctuated by intense bursts of rainfall. According to the United States Geological Survey, California receives approximately 230 million acre-feet of water annually, but this is unevenly distributed, and demand often exceeds supply.
The current dry spell, lasting almost four weeks, has heightened concerns about water resources and wildfire risk. While reservoirs remain at generally acceptable levels, the lack of rainfall has contributed to drier vegetation, increasing the potential for wildfires. The National Weather Service has been closely monitoring the developing storm systems, providing updates and forecasts to residents across the state.
Storms on the Horizon: A Phased Approach
The first system, arriving Monday evening, will primarily impact California’s far North Coast, bringing periods of light to moderate rain to areas like Eureka and Crescent City. This precipitation is particularly crucial for Humboldt and Del Norte counties, which have seen significantly below-average rainfall in December.
A second, weaker system will follow on Wednesday, bringing light rain to the North Bay and potentially a trace amount to San Francisco and Oakland. While this storm won’t be a major rain producer, it will technically end the dry streak. However, the most significant rainfall is expected with a third system arriving late Friday into early Saturday.
Pedestrians use umbrellas and rain jackets to shelter from the rain in San Francisco as a storm passes through the Bay Area on Nov. 5.
Lea Suzuki/S.F. Chronicle
The Sierra Nevada: A Critical Snowpack Boost
The anticipated snowfall in the Sierra Nevada is particularly significant. California’s snowpack provides approximately 30% of the state’s freshwater supply, making it a crucial resource. As of November 28th, the California Department of Water Resources reported that the statewide snowpack is currently at 31% of its historical average for this date. A substantial snowfall event this weekend could help to close that gap and improve water storage for the coming year.
The upcoming storm is expected to lower snow levels, potentially bringing several inches of snow to elevations as low as 6,000 feet. This is a welcome change from previous storms, which have primarily produced rain at lower elevations. Ski resorts across the Sierra Nevada are eagerly anticipating the snowfall, hoping to open more terrain and attract visitors during the holiday season.
Looking Ahead: An Active Pattern
Beyond this week, meteorologists are predicting an active weather pattern for California, with continued chances of rain and snow into Christmas week. While the storms are not expected to be as intense as those experienced earlier this year, they will provide a much-needed boost to water resources and help to mitigate wildfire risk. The World Meteorological Organization reports that global average temperatures are currently 1.4°C above pre-industrial levels, contributing to more extreme weather events worldwide, including prolonged droughts and intense rainfall.
The return of rain is a reminder of the delicate balance of California’s water resources and the importance of proactive water management strategies. As the state continues to grapple with the challenges of climate change, it will be crucial to invest in infrastructure, conservation efforts, and innovative technologies to ensure a sustainable water future.
Monday Bay Area Forecast: Expect partly cloudy skies with mild temperatures. Highs will range from the upper 50s to low 60s. Low clouds will return overnight, with lows around 50 degrees.
ARTICOL ORIGINAL:
Pedestrians use umbrellas and rain jackets to shelter from the rain in San Francisco as a storm passes through the Bay Area on Nov. 5. Rain is expected to return to the region this week after a nearly four-week dry spell.
Here’s how the week shapes up, storm by storm.
Storm 1: Rain for the North Coast only
The first system arrives Monday evening, but its impacts will be limited to California’s far North Coast in Humboldt and Del Norte counties. It’s welcome news for Eureka, where just 0.11 inches of rain has fallen in December, nearly 3.5 inches below normal.
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A cold front tied to a distant low pressure system near British Columbia will bring periods of light to moderate rain from Monday afternoon through Tuesday morning to places like Eureka, Crescent City and the Siskiyou Mountains.
Monday’s system is the weakest of the bunch this week and will just bring meaningful precipitation to the northern California coast.
Beyond that, this initial storm won’t be felt anywhere else in the state. Without stronger support from a closer in proximity parent low pressure system, the cold front will fall apart early Tuesday morning. As a result, measurable rain will not reach the Bay Area, and most locations south of Mendocino County will stay dry.
Storm 2: Just enough to break the dry streak
The next chance at precipitation arrives quickly on the heels of the first, with rain redeveloping along the North Coast by Tuesday afternoon and evening. This cold front will be stronger and more efficiently tapped into moisture from the Pacific, and will push farther south along the California coast. All of that adds up to a more impactful rainfall event.
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Light rain will spread into Mendocino County, the northern Sacramento Valley and the Sierra foothills late Tuesday, most likely after sunset, and persist overnight. Meanwhile, after midnight Wednesday, light to moderate rain will reach the North Bay, particularly along the Highway 101 corridor.
Light rain showers will spread into San Francisco, Oakland and along the Peninsula in the predawn hours Wednesday. That should make for a slightly wet early morning commute Wednesday morning.
Rainfall should reach the Bay Area on Wednesday morning, but totals will be very low.
Despite having a more widespread impact, Wednesday’s storm system will be weakening as it moves south through California, keeping rainfall totals modest. By the time the rain ends Wednesday morning, upward of 0.25 inches of rain will have fallen in the North Bay along the Highway 101 corridor, while most areas south of the Golden Gate are likely to see no more than a tenth of an inch. That’s enough to technically end the dry streak, but otherwise not impactful at all.
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Unfortunately, neither of the first two storm systems will provide much relief for the snow-starved Sierra Nevada. Snow levels for both systems will remain high, hovering near 8,000 feet, meaning precipitation will fall as rain at most Sierra ski resorts. Only the highest elevations are likely to see light snowfall.
Storm 3: The one worth watching
The third storm system, expected to arrive late Friday into early Saturday, offers the best chance for meaningful rain across the Bay Area and a more favorable setup for snowfall in the Sierra.
By the end of the week, the jet stream is forecast to tighten and align more directly from west to east across the Pacific, a configuration that favors cold fronts holding together as they move into California. That jet will also tap into a plume of subtropical moisture, and a surface low pressure system is expected to develop off the Northern California coast, helping to generate more substantial precipitation as it moves inland and southward.
The storm system at the end of the week will have the benefit of tapping into an atmospheric river pointed more toward the Bay Area.
Rain is likely to spread into the North Coast late Thursday night, then expand southward through the North Bay on Friday morning. Steadier rain should reach San Francisco, the East Bay and the South Bay by Friday afternoon and evening.
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It’s still too early to lock in exact totals, and the exact timing of the rain is likely to change a bit as we get closer. But this system has the highest precipitation potential of the week. North Bay valleys could see between a half-inch and 1.5 inches of rain, with closer to a half-inch possible in San Francisco and Oakland and lower totals farther south.
This system also brings the best snow prospects the Sierra has seen in weeks. Snow levels are expected to drop compared to earlier storms, potentially falling to around 6,000 feet by Friday night. While the system will move through relatively quickly, a few inches of snow could fall at lower elevations by Saturday, offering a much-needed boost for ski resorts.
Once the storm exits early Saturday, conditions should dry out quickly.
Each one of these systems helps to open the door a bit more for more rain and snow chances for California beyond next weekend. An active pattern looks likely to continue into Christmas week, though at this point the signal favors progressive storms and moderate rainfall rather than prolonged or extreme events.
Monday Bay Area breakdown:
San Francisco:Monday will start out with mostly cloudy skies across the city. The low clouds should break up by the late morning and early afternoon, leaving some high-altitude (above 25,000 feet) clouds and partial sunshine for the rest of the day. Temperatures will be a bit warmer than Sunday, with afternoon highs in the low to mid-50s. Low clouds and fog return overnight with lows in the upper 40s to low 50s.
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North Bay:Monday is likely to end up mostly cloudy across the North Bay, especially along the immediate coast. A few breaks of sunshine are possible along Highway 101 in the afternoon, but it won’t help with the cool temperatures. Highs will be in the upper 40s in Vallejo and Vacaville and in the mid-50s in Novato and Santa Rosa. Clouds and fog return overnight, with lows ranging from the upper 40s to low 50s.
East Bay:Morning clouds will give way to partial sunshine by the afternoon, especially from Richmond down to Fremont, where highs will be in the upper 50s to around 60 degrees. The clouds will linger a bit longer in the Tri-Valley and Livermore Valley, but sunshine should pop out there as well, with highs in the mid-50s. In Northern Contra Costa County, Walnut Creek and Concord will remain overcast for much of the day, with highs in the upper 40s. Clouds return for most spots overnight, with lows in the upper 40s to low 50s.
Peninsula:Low clouds and fog will cover the Highway 101 stretch on Monday morning. Skies will gradually clear as the day progresses but will never be completely cloud-free. Temperatures will be pretty uniform along the Peninsula, with highs in the upper 50s from South San Francisco down to Redwood City. Clouds will return overnight, and temperatures will be mild, with lows right around 50 degrees.
South Bay:Low clouds will hang across the South Bay through much of Monday morning. Partly sunny skies will develop by the afternoon, with mild temperatures. Highs will generally be in the upper 50s to low 60s. Low clouds return overnight, but conditions remain stay mild, with lows about 50 degrees.