Yesterday off the coast of Northern/Central California a classic coastal jet was observed on the Quickscat sea winds satellite. Here’s a composite image showing the jet (the gale-force winds indicated by the red and black flags).

The factors that influence coastal jet formation are numerous and somewhat complicated. However, the California coastal jet can generally be described as the interaction of the semi-permanent east Pacific high pressure system and the temperature-driven western US low-pressure system. For a good introduction to coastal jet formation, you can view this web-based mini-course on the MetEd site (registration required, but free).

If you want to know how they remotely measure sea winds, here is a link to a good mini course on it from the MetEd site. You have to register, but it is free.

Remnants of former hurricane Cosme are going to pass close to Hawaii later in the week. It won’t be up to much, so at worst probably just some winds and rain. Here’s the forecast track from the hawaii.edu storm page.

It actually rained in The City today (San Francisco, CA)… not very much just 0.02”. It did, however, set a record for today, since it has never rained in recorded weather history on July 18th.

From today’s area forecast discussion:

IT HAS BEEN A RECORD SETTING MORNING. DOWNTOWN SAN FRANCISCO HAS HAD 0.02 INCHES OF RAIN THIS MORNING…WHICH IS A RECORD FOR THIS DATE. THE PREVIOUS RECORD FOR DOWNTOWN SAN FRANCISCO WAS…ZERO! RECORDS HAVE BEEN KEPT FOR DOWNTOWN SAN FRANCISCO FOR MORE THAN 150 YEARS! LIGHT TO MODERATE RAIN HAS FALLEN LAST NIGHT AND THIS MORNING ACROSS MOST OF THE BAY AREA NORTH OF SAN JOSE. RAINFALL TOTALS HAVE BEEN MORE THAN 0.2 OF AN INCH IN PLACES OF THE NORTH BAY…WITH 0.1 INCHES OR LESS ACROSS THE BAY AREA…AND EVEN UP TO 0.02 INCHES IN LA HONDA AND BEN LOMOND.

Here’s the doppler radar image showing the system a little later in the day.

And the 1 KM visible satellite image.

The Day Forest Fire down in Southern California is a big one. So far it was burned 74,052 acres. How big is that? Check out the yesterday’s smoke blotting out the sky around Santa Barbara, California.

The fire is so large that it shows up on the IR satellite image too.