HOW TO USE (BUT NOT ABUSE) LOLA
By Sean Collins and Steve Hawk
Copyright Surfline 2001 All rights Reserved.

These maps allow you to zero in on a coastal zone and see how distant swells are taking aim on your hometown. Swell Tracking Maps are a way of translating straight lines from a three-dimensional globe to a two-dimensional page. With flat maps of the earth, the shortest distance between two points is actually a curved line, not a straight one. These lines are called Great Circles.

IMPORTANT: The colored lines on the Swell Tracking Maps and the colored numbers in the text table on the left indicate what predicted SURF heights will be when the waves break on the coast. (Surf heights are the average to maximum breaking wave heigths measured on the face of the wave from crest to trough.) They are not a measurement of what the wave heights are farther out to sea.

To see a looping sequence of how a specific swell will progress over the next 120 hours (five days), click on the word "Loop" above the map. To freeze the map at any point in the future, click on one of the six numbers to the left of the word "Loop" (0, 24, 48, etc.). If you click on the number 48, for instance, the map shows what the incoming swell will look like two days from today.

The dated graph on the left forecasts combined deep water swell heights over the next two weeks.

The text table at the bottom left is a quick-reference, long term forecast of size, wave period and direction for Surf Heights (breaking waves on the coast) on the Swell Tracking Maps. Forecasts under three days tend to be sharp, and anything between three and seven days is typically reliable but not guaranteed. Forecasts that look ahead more than seven days may include a lot of guesswork, but they can alert you to potential storms and swells worth watching.

This is a long-term, localized forecast showing the deep water wave period and sizes of the top five incoming swell trains over the next 10 days. The colored lines represent different periods: blue for eight seconds, red for 14 seconds, purple for 20 seconds, etc.

The five rows of numbers below the chart show periods of the top five swells over the same 10 days, with the strongest swells listed first.

This page is a good way to measure the breadth of a swell, indicating whether an incoming swell has a wide directional spectrum with a 15- to 90-degree variance in swell direction, or a narrow directional spectrum with a 0- to 15-degree variance in swell direction. A storm close to shore with a wide fetch will result in a wide directional spectrum with a broader range of swell directions. If the swell travels from a storm far away, or from a storm with a narrow fetch, the directional spectrum will be narrow and the swell direction will be focused within a few degrees. The narrow blue streaks running vertically through the chart are not graphic mistakes -- they show where oceanic islands will shadow a specific coastal zone from a particular swell direction.

The graph on the right (H) shows how deep water swell heights will progress over the next 14 days, or 14 days beyond whatever date is picked in the time-control bar in the chart's upper left-hand corner.

Your locale is at the bottom of the map. This page helps determine whether a swell is coming from a nearby storm or a distant storm. It is nearly identical to the "Height v. Time" page , except that it shows an incoming swell's distance from your homebreak in nautical miles rather than hours.

The graph on the right (H) shows how deep water swell heights will progress as the swell train moves closer to your coast.

Intro • Buoy Observations • Five Day Forecasts • Swell Tracking Maps