WASHINGTON – A pleasant September day five years ago suddenly turned tragic when a huge wave loomed out of the ocean and swept two people to their deaths at Acadia National Park in Maine. The culprit, some 1,000 miles away, was Hurricane Gert.

With hurricane season now under way, forecasters hope to prevent similar deaths by issuing severe-wave and tide warnings using a prediction system called Wavewatch III.

“What many people may not realize is that, if a major hurricane is striking the Caribbean, it can also result in dangerous waves and surf conditions in the Gulf of Mexico and up the East Coast as far north as Long Island and Cape Cod. Similarly, surf conditions can become dangerous days before the storm arrives on the coast,” said Hendrik Tolman of the National Oceanic and Atmospheric Administration’s Environmental Modeling Center.

Added Joseph Sienkiewicz of NOAA’s Ocean Prediction Center: “The real issue is safety.”

A storm that can be hundreds of miles out at sea can make beaches untenable, Sienkiewicz said. In the case of the Acadia park drownings, Hurricane Gert was near Bermuda but generated swells that affected much of the East Coast.

Forecasters can currently issue three-day wave forecasts and plan to expand that later this summer to five-day warnings ahead of a storm.

People know that if a hurricane hits them, they are in trouble, Tolman said. But they aren’t aware that a storm on the other side of the Bahamas can pose a threat to the U.S. coast.

“It’s almost always beautiful weather on the coast before a hurricane strikes,” he noted, but dangerous waves and rip currents can come well ahead.

Wavewatch III is what is called a suite of forecast models.

That means reports of weather and ocean conditions worldwide are fed into giant computers that use a complex series of mathematical formulas to calculate how conditions will change over time.

The overall worldwide model, continually updated, looks 180 hours into the future, and the more localized model concentrating on the tropical Atlantic anticipates conditions 72 hours ahead, Sienkiewicz explained.