San Francisco Bay South of the Bay Bridge Marine Forecast
| Today...Nw Winds 10 To 15 Knots...Increasing To 15 To 20 Knots With Gusts Up To 25 Knots This Afternoon. |
| Tonight...Nw Winds 15 To 20 Knots With Gusts Up To 25 Knots. |
| Mon...S Winds 5 To 10 Knots. |
| Mon Night...S Winds 10 To 20 Knots With Gusts Up To 30 Knots. Rain. |
| Tue...S Winds 15 To 25 Knots With Gusts Up To 30 Knots. Rain. |
| Tue Night...S Winds 10 To 20 Knots With Gusts Up To 25 Knots. Rain. |
| Wed...Se Winds 10 To 15 Knots. Rain. |
| Thu...W Winds 5 To 10 Knots. |
| Area Forecast Discussion National Weather Service San Francisco Bay Area 1102pm PDT Sat Mar 25 2023 Synopsis Chilly overnight and early morning temperatures with drier conditions through Monday morning. Prepare for another round of wind and rain for early next week with the brunt of the storm's impacts expected on Tuesday. ...Wind and Rain Impacts Early Next Week As of 08:39pm PDT Saturday...Mostly clear skies from Sonoma county down to Monterey.Some lightly patchy clouds are still lingering attached to the higher peaks from the South Bay and southward, but they are struggling to remain upright with the setting sun. The short term impact is the moderate risk for cold temperatures overnight. Half Moon Bay even tied their daily low temperature record for March 25th of 35 degrees Fahrenheit, the original set back in 1942. Another cold night forecast into Sunday morning. No changes were made to the Frost Advisory as inland areas will see the chillier conditions while the coastal areas will be moderated by the ocean. Otherwise Sunday afternoon looks to be similar to Saturday in that it will feature mostly clear and sunny skies with similar below normal temperatures. The rest of the forecast is in preparation for Tuesday storm. It is looking more and more likely that it will arrive in northwest Sonoma County Monday evening and slowly move southward through Tuesday. There is some indications of hesitation on its southward progress when it gets west of San Francisco, but signs point to it continuing to move along rather than stalling and causing bigger issues. The good news is, is that most models are suggesting that the center of the low will be at its deepest farther offshore; otherwise, it seems similar in set up to last Tuesday. The coastal areas will likely receive the strongest wind gusts and most total precip, while the valleys will remain more rain shadowed and wind sheltered. That being said, it bares repeating that soils are saturated so it will not take much for winds to knock down a tree and/or cause a power outage. The cooler temperatures tonight will lower snow levels, but thankfully there is no precipitation until Monday night. By then, warm air advection will raise those snow levels above 3,500 feet. There is the chance for some of the highest peaks to get some snowfall with this system, but it is not expected to result in major impacts at this time. Beyond that, look for lingering scattered showers Wednesday and Thursday as the center of low pressure exits southward with morning low temperatures once again cooling. As of 02:47pm PDT Saturday...Today through Monday: Dry weather conditions prevail over the region this afternoon with temperatures generally in the mid-to-upper 50s with 40s in the higher terrain. In addition, breezy northerly winds prevail as well with gusts between 20 and 35 mph and colder air aloft continues to advect into the region. With this, expecting little change in weather conditions for Sunday with it starting off chilly-to-cold. Of note, temperatures the past few mornings have not cooled as much as previous forecast due to the aforementioned winds keeping the boundary layer well mixed. Similar issue is expected again tonight into Sunday morning. However, still expecting widespread frost impacts across most interior locations across the greater San Francisco Bay Area and Central Coast. Short of the long, another cold night in store region-wide. As such, a Frost Advisory remains in effect through Sunday morning at this time. Monday morning may also be as cold if not colder depending on the surface winds which are anticipated to diminish ahead of our next weather system. The increased in cloud cover and moisture will also play a role in forecast low temperatures on Monday and therefore confidence remains moderate with the potential need for another Frost Advisory into Monday morning as well. Individuals in homes without power as well as the unsheltered or marginally sheltered populations will be at risk in these cold early morning temperatures. Monday night through Tuesday night: A mid/upper level low pressure system will drop out of the Gulf of Alaska and down off of the British Columbia coastline late the weekend. The weather system will then approach the Pacific Northwest and northern California coastlines late Monday. This will drive a cold front into the region on Tuesday with southerly winds strengthening ahead of the boundary late Monday night. As the boundary moves through, southerly winds will remain breezy with gusts between 40-50 mph across much of the region and potentially greater than 60 mph in the favored coastal gaps, ridges and peaks. These wind speeds, even for a short period of time, will increase the risk for downed trees and tree limbs resulting in isolated power outages. Wind speeds are forecast to diminish in wake of the frontal passage by late Tuesday afternoon and/or evening. Rain will increase in coverage and intensity late Monday night over the North Bay and through the San Francisco Bay Area early Tuesday morning. An early look into the high-resolution models indicates the potential for the development of a narrow cold-frontal rainband (NCFR) as the boundary progresses southward through the Central Coast. That said, periods of moderate to locally heavy rainfall are expected on Tuesday along the main frontal boundary which will result in an increased risk for urban and small stream flooding, ponding of water on roadways, and shallow mudslides/rockslides. There is also a 10-20% probability of thunderstorms on Tuesday as the air mass becomes more unstable just along and in wake of the frontal passage. At this time, the North Bay has the greatest potential for thunderstorm development from late Tuesday morning into the afternoon. Scattered to numerous rain showers will persist in wake of the frontal passage as the core of the mid/upper level low lingers off of the Northern California coast. Rainfall amounts are forecast to range from 0.75-1.75" in the North Bay and other coastal areas of the Bay Area/Central Coast, 1.50-3.00" in the North Bay Mountains and coastal ranges, and 0.50-0.75 for most inland urban areas. Meanwhile, snow levels will range between 2,500-3,500 ft Monday night into Tuesday morning before rising to above 3,500 ft during the bulk of the precipitation. Thus, snow accumulations are likely in the highest peaks of the Bay Area and Central Coast, yet should have minimal impacts to the general public. Tuesday night into Thursday: The mid/upper level low will begin to shift southward and traverse the central California coast on Wednesday. This will keep the potential for isolated to scattered rain showers and high elevation snow showers into Wednesday if not early Thursday morning. The eventual track of this system will determine exactly when conditions begin to dry out region-wide. Thursday night and beyond: Drier conditions develop by Friday. However, overnight/morning temperatures will turn colder once again as cold air settles in over the region. Forecast confidence decreases for the next weekend and into early next week. However, there is good agreement with a the pattern over the West Coast remaining troughy with cool and potentially unsettled weather. Stay tuned... Marine as of 10:45pm PDT Saturday...Strong high pressure to the north and low pressure to the south will maintain strong northerly winds over the coastal waters. Gusty, gale force winds will continue through early Sunday, especially along the immediate coast south of Point Sur. Larger swell mixed with gale force winds will create hazardous seas up to 15 feet in the outer waters. A low pressure system develops over the eastern Pacific bringing rain and wind to the coastal waters and bays early to mid next week. NOAA San Francisco Bay Area Office: Watches - Warnings - Advisories Tonight: Frost Advisory...CAZ503-504-506-510-512>518-528-529 Small Craft Advisory...San Francisco Bay until 3am Small Craft Advisory...Monterey Bay until 3am GALE WARNING...Point Arena to Point Reyes 0-10nm until 3am GALE WARNING...Point Reyes to Pigeon Point 0-10 nm until 3 AM GALE WARNING...Pigeon Point to Point Pinos 0-10 nm until 3 AM GALE WARNING...Point Pinos to Point Piedras Blancas 0-10 nm until 3 AM GALE WARNING...Point Arena to Pigeon Point 10-60nm until 3 AM GALE WARNING...Pigeon Point to Piedras Blancas 10-60 nm until 3 AM |
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