by Mike Godsey,

Indecisiveness

I have inserted my forecast for today June 11 in this image so that you can see the indecisiveness in my forecast.

The reason for this is that the San Francisco Bay Area is right intersection between 2 massive weather systems.

First let’s take a close up view first to see the forecasting issue today.

In the top image notice how the North Pacific High’s NW winds are focused just north of Waddell and into Monterey Bay. While to the north the storms southerly wind start building past Bodega Bay.

Also notice how weak the ocean winds are outside the Golden Gate in the transition area from NW to SW winds. So why are fairly strong winds forecast from the Golden Gate to Sherman Island today?

The Bay Area has 2 basic wind machines.

1. The North Pacific High’s NW winds which fluctuate in strength from day to day depending upon the location of the NPH.

2. The thermal winds created by low-pressure in the Central Valley as it heats up each afternoon.

Typically our spring through fall winds are a combo of these 2 wind machines. But today with the North Pacific High’s NW winds largely absent we are running on just one wind machine.

Fortunately, the Central Valley wind machine is robust today with a strongest pressure gradient towards Sacramento which helps the winds in the Central Bay to Sherman Island.

Now lets look at the big picture.

In the bottom image notice how distorted the North Pacific High has become. The bulk of the NPH is actually located NW of Hawaii.

But notice how a ridge from the NPH is still reaching out to the California and Baja coasts which receive strong NW wind today. Now check out the huge low-pressure storm west of Oregon and Washington and Northern California. Checking the ocean buoys in that area you will see southerly storm winds.

Unfortunately, it looks like the Bay Area stays in this transition area for the next couple of days. If the storm moves southward our winds weaken. If it moves northward the North Pacific High’s NW winds move back to our coast. Forecasting this will be a challenge.