Rating scale is in forecast for El Nino conditions

Hurricanes and tornadoes have popular rating scales that help people understand their power. Now, weather experts are planning a similar way to measure the El Nino phenomena that affect climate worldwide.

The ratings are tentatively expected to begin in the fall, said Wayne Higgins, director of the federal Climate Prediction Center. Higgins said his forecasters also are planning watches and advisories, as is currently done with other severe weather.

A watch would be issued when conditions are right for potential development of an El Nino or La Nina within three to six months, he said. An advisory would mean the condition was underway.

In recent years researchers have found that El Nino, a periodic warming of portions of the tropical Pacific Ocean, and its cool opposite, La Nina, can have significant impacts on weather around the planet.

The Climate Prediction Center, a division of the National Oceanic and Atmospheric Administration, monitors these conditions, known collectively as ENSO -- El Nino-Southern Oscillation.

The planned five-point scale would help assess the effects after the fact, he said, much as the Fujita scale is now used following a tornado.

The Saffir-Simpson hurricane scale is also used to assess damage after a hurricane, but it also is often cited as a storm approaches, using estimates based on wind speed to help people understand the imminent danger.