Hoping to better predict deadly rip currents, the National Weather Service has enlisted California beach lifeguards to watch and record rip current patterns.

Using Moonlight State Beach in Encinitas as a test lab, NWS has collected data from lifeguards to update an existing rip current model predictor. The next step is to repeat the program and collect more data farther north in Manhattan Beach. In time, researchers hope to expand to beaches around the country, including the Great Lakes in the Midwest.

?The key to this is to have lifeguards on the beach and [making] these observations,? said Stephan Smith, chief of the decision assistance branch for the NWS? Meteorological Development Lab in Silver Spring, Md. ?They?re the eyes and ears for this whole thing.?

Rip currents are channeled currents that flow away from the shore and are responsible for nearly 80 percent of lifeguard beach rescues. These swift-flowing belts of water are the No. 1 cause of drowning at ocean beaches, and can be so strong that even expert swimmers can be swept out to sea.

Rip currents are caused by deep ocean swells, storms, underwater topography, water level and ocean waves. Using lifeguard observations of wave height, direction, timing and rip current strength, Smith hopes to gain a better indication of rip-current risk, with an approximate lead time of one to two hours.

?From a scientific viewpoint we?re just trying to understand the currents and compile more quantitative data,? said Dr. C-S Wu, senior physical scientist at NWS. ?If we can combine rip currents with our wave forecasting capability, then we can give beach-goers the appropriate warnings.?