Marine Weather Net

San Francisco Bay north of the Bay Bridge, including San Pablo Bay, Suisun Bay, and West Delta, CA Marine Forecast









The Marine Weather Forecast In Detail:
PZZ530 Forecast Issued: 844 AM PST Wed Dec 02 2020

Today...Ne Winds Up To 10 Kt, Becoming Nw This Afternoon.
Tonight...W Winds Up To 10 Kt.
Thu...Ne Winds Up To 10 Kt.
Thu Night...N Winds Around 5 Kt.
Fri...N Winds Around 5 Kt.
Fri Night...N Winds Around 5 Kt.
Sat...N Winds Around 5 Kt.
Sun...N Winds Around 5 Kt.
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844 AM PST Wed Dec 2 2020
Synopsis for the Central California Coast and Bays Including the Monterey Bay, Greater Farallones and Cordell Bank National Marine Sanctuaries - PZZ500
Surface high pressure over the eastern Pacific and a stronger surface high over the Great Basin will keep light northwest to north winds going across the coastal waters and bays through Sunday. A long period northwest swell arrives today to early Friday bringing potential hazards in the surf zone.
Area Forecast Discussion
National Weather Service San Francisco Bay Area
928am PST Wednesday Dec 2 2020

High pressure, along with light offshore flow, will maintain dry conditions across the region through the upcoming weekend, and likely through at least the first half of next week. Days will be mostly sunny and mild while nigheights will be clear and cool.

as of 08:40am PST Wednesday...The potential for low level moisture, as mentioned in the previous discussion, did manifest itself as a few patches of dense fog in the North Bay Valleys this morning. Luckily, this fog stayed within the lowest elevations and did not see widespread development. Offshore flow and quickly warming conditions have already started to clear some of these patches, setting the Bay Area up for another sunny and clear afternoon. Morning lows again fell around 5 degrees below average in several places, but with another sunny and dry afternoon, these temperatures look to quickly turn around. The gradient from WMC to SFO has increased since the last discussion, and is up to 12.9mb. However, winds still look to remain moderate.

clear early this morning, except for some passing high clouds. This is in marked contrast to 24 hours ago when widespread low clouds and fog blanketed the coast and were developing inland. The difference this morning is that pressure gradients have turned offshore, resulting in widespread north to northeast winds in the hills with light offshore flow at several lower elevation locations as well. Surface dewpoints are similar to yesterday morning, so we may still see some patchy low clouds and fog develop prior to sunrise, but it's highly unlikely that that anything other than patchy fog will form this morning given offshore flow conditions.

Currently, the offshore pressure gradient from WMC to SFO stands at a rather impressive 11.5 mb, but most of this gradient spans the Sierra. Thus, only locally moderate offshore winds are currently being observed in our hills, mainly at the higher elevations of the North and East Bay where gusts of between 20 and 30 mph are being reported. Winds in the hills are expected to peak over the next few hours and then subside for the balance of the day. In fact, while southern California is expecting a significant Santa Ana wind event over the next few days, offshore flow in our area is forecast to remain mostly light in the short term. Our recent prolonged period of dry weather is resulting in fuels approaching near record dry levels for early December. Thus, absent any precipitation, a strong offshore wind event at this point would likely result in critical fire weather conditions. The latest models indicate that after this morning, winds in our hills will remain light through midday Sunday. However, the latest GFS and ECMWF (European Centre for Medium-Range Weather Forecasts) both indicate the potential for gusty offshore winds in the hills of the SF Bay Area from Sunday afternoon through Monday evening as an upper trough develops over the Great Basin. Will need to monitor this closely for potential Fire Weather Watches or Red Flag Warnings.

Other than potential fire weather concerns by late in the weekend, and beach hazards over the next few days due to powerful long period swell (see Beaches section below), our weather will be uneventful through the forecast period as an upper ridge remains over California and offshore flow prevails. Daytime temperatures will remain mild and slightly above normal, while nigheights will continue to be cool. No rain is expected over the next 7 days. A frontal system currently offshore along 140W is forecast to wash out as it comes up against the ridge late tonight and Thursday morning. Rainfall with subsequent incoming systems is forecast to remain to our north, at least through the middle of next week. of 9:30am Wednesday...A very long period WNW swell will impact the Sonoma to Big Sur coast today through Thursday afternoon. Initial forerunner waves of 24 to 27 seconds will begin to arrive along the Sonoma coast early this morning before spreading southward through the day. The primary timeframe of concern from this event will be midday today to Thursday morning as the wave heigheights rise to 3 to 7 feet at a periodicity of 19 to 24 seconds. A high to extreme risk of sneaker waves will exist during this timeframe. The largest energetic sneaker waves will arrive irregularly every few minutes to as infrequently as once every 30 minutes during otherwise deceptively calmer seas and consequently may catch those on coastal jetties, rocks, piers, or shorelines offguard and may injure them or knock them into the cold, turbulent ocean. Beachcombing is not advised during this timeframe. In addition, strong rip currents will accompany the energetic wave train, particularly at WNW facing beaches. These type of events claim lives each year along our coast so extreme vigilance is advised if visiting the coast. Finally, moderate to locally large breaking waves of 14 to 18 feet will be possible later in the day on Thursday at WNW facing beaches as the swell period decreases and swell heigheights increase, thus this product will be in effect through the day Thursday. A beach hazard statement is in effect from 10am today to 4pm Thursday.

as of 09:22am PST Wednesday...Surface high pressure over the eastern Pacific and a stronger surface high over the Great Basin will keep light northwest to north winds going across the coastal waters and bays through Sunday. A long period northwest swell arrives today to early Friday bringing potential hazards in the surf zone.