Step 5: When will the waves hit?

Luckily, there are lots of buoys near the coast, so you can probably choose one right at your beach. All you need to do is go back to the National Data Buoy Center page (the URL is at the bottom of this page), and find the buoy nearest your beach. We'll choose 46042, which is just off the coast of Monterey Bay, not far from Santa Cruz.

When you look at the buoy page, you'll see that there's all sorts of interesting information there about current wave heights, temperature, etc. This is a good last-minute resource to check if you're wondering whether you should duck out of work early and hang ten.

From the buoy page, we can get this buoy's location, 36°45'11"N and 122°25'21"W. To find the distance between that buoy and the waves near our other buoy (located at 37N and 160W), we can use this handy-dandy on-line calculator. You'll find it at http://jan.ucc.nau.edu/~cvm/latlongdist.html . Plugging in our coordinates, and making sure we choose our answer in nautical miles, we figure the waves are 1795 miles out.

Basic physics says "time = distance ÷ speed." So the time it will take for these waves to reach our beach is:

1795 nautical miles ÷ 20.3 nautical miles per hour = 88.4 hours, or 3 days and about 16 1/2 hours.

Our model begins at 6 a.m. on February 6. Adding 3 days and 16.4 hours to it, we predict that the waves we're tracking now will hit our beach at about 10 p.m. on Feb 9. We won't be surfing at night, but chances are we'll find good things coming our way if we're out in the ocean the afternoon before our breakers arrive.

Of course, no forecast is ever guaranteed, and we're working with some approximations here. So if you do plan ahead to take the afternoon off, it's still a good idea to check conditions before you go out. You can use the same charts you've been using through this exercise to see how fast and how high the waves are at your beach.