by Mike Godsey, mikeATiwindsurf.com

jmarik wrote about Part 1 of this blog:
Hi Mike,
Does this explain why 3rd Ave. channel was ripping while SFO was reading only low 20’s today?
Cheers.

Hi jmarik,

I think you are probably right about the SFO winds.

As you can see in this first image of yesterday’s standing waves produced by the W to WNW 975mb winds at about 1000 feet aloft touch down in pretty well-defined bands and my guess is that SFO was just on the edge of a band.

Today we also have strong surface winds AND strong winds at 1000 feet. But there is a big difference!

Looking at the next image note that the winds just aloft today are more NW so they hit the coast range at an angle.

That allows them to flow through the many W to NW facing gaps in the coast range as you see in the next image. So the winds aloft smoothly enhance the surface wind as you see in the next image below

While yesterday the winds aloft hit the coast range at near 90 degrees which is much more likely to create standing wind waves.

Compare today’s wind distribution below with yesterday’s in the above image. Really dramatic.

This wind direction aloft also allows the surface wind to build earlier since we don’t have to wait for the standing waves to form over the Bay waters.

In the last image from just after dawn there is already strong wind at some sites.

And the winds today should be a bit steadier today since the standing waves have rotor wind in the lull areas between bands which create crazy gusts and lulls.

If you have ever sailed or kited the Gorge you know how crappy the winds can be in the corridor from Viento to Dougs.

This is because such bands are very common in the Gorge due to all the points and ridges that just out into the river. While in the Bay Area such bands only occur when the 975 winds are more westerly and strong which is rare.

 

The Gorge has beautiful swell and powerful wind but in terms of quality steady wind, it pales compared to the Bay Area.