By Mike Godsey

Video: different perspectives of the today’s eddy


by Mike Godsey,

First find the Golden Gate in the video. Then watch for the counter-clockwise spinning winds west of the Gate. The first image shows deep fog covering much of the central bay and the North Bay. Especially notice the huge streamer of fog curving from the Golden Gate into Napa Valley. Normally this the eddy would weaken by 11AM and this flow would turn the normal WSW and really jazz up the Sherman Island winds. This happened to late today for Sherman Island to reach the mid 20’s as I forecast. Such is the fickle nature of eddies. To learn more about how this eddy killed the coast and Peninsula winds today keep reading.

I first “discovered” this eddy about 12 years ago during a trip out of Bodega bay on one of our boats. Leaving Bodega we headed due west for about 10 miles into building NW wind and swell. Then we dropped due south rounded Pt. Reyes and headed towards Pacifica. As we did this we gradually left strong NW wind to calm winds and then, amazingly, pure SOUTH wind. At the time it did not make any sense. How could there be strong northerly wind and mild southerly wind just a few miles apart?

Later looking at the crude satellite imagery then available I realized that in certain conditions a counter-clockwise spinning eddy would form just west of the Golden Gate. At the time there was no mention of this eddy in any of the literature so I felt free to give it a name: The Golden Gate eddy. You can see this counter-clockwise spinning eddy just west of the Golden Gate in the video imagery to the right. The video goes from about 7AM until 5 PM today.

To understand the video better scroll down to the graphic next graphic.

In the top image notice how complex the eddy flow is today. Some days it is a perfectly formed eddy other times it more like today. In the same image find the San Pablo Bay sensor and notice how SW its winds are at 7:33AM today. At dawn those winds were pure South and shooting wind and fog into Napa Valley.

This southerly flow deprived Sherman Island of its Dawn Patrol wind and kept the winds much weaker than forecast all day. Normally the eddy shrinks mid day and San Pablo Bay sensor winds would turn more WSW and Sherman Island winds will pick up. This was not a normal day.


The second image shows a  models version of this eddy. Many times the models do not even “see” this eddy and we have to use satellite imagery and wind patterns to infer the existence of the eddy.
Golden Gate eddy

The last image is a bit confusing unless you are used to looking at satellite imagery. First find the outlines of the Bay Area and the Golden Gate. The look west and you can barely see the eddy in the fog.

Some days it looks like a tiny slo mo hurricane other days it is tricky to visualize. But you can clearly see the broad streamer of fog the sweeps over the central bay, over San Pablo Bay and into Napa and Sonoma valleys.

All of this SW flow from the eddy will keep the coast winds weak today. And Coyote and 3rd. Ave. can expect shifty weak SW wind inside. Even Crissy may be tricky inside due to fog and weak winds until late.