2 climate conditions may mean fewer storms

For Florida residents, the big question is whether the state can make it through the fourth storm season in a row without a hurricane crossing its shoreline.

The 2009 season arrives Monday, and forecasts call for it to be slightly above average with nine to 14 named storms, up to three of which could become major hurricanes with winds of 111 mph or higher.

That would be a drop from 2007 and 2008, which brought a total of 32 named storms - nearly as many as typically seen over three seasons.

Two climate conditions are behind the lower forecast.

Water temperatures in the eastern Atlantic Ocean are slightly below normal, providing less fuel for developing storms.

There's also the slight warming of water over much of the equatorial Pacific Ocean, marking the disappearance of a La Nina that helped produce the surge in storms the past two seasons.

A La Nina, or cooling of water in the Pacific, reduces winds in the jet stream blowing from the west. The lower winds make it easier for hurricanes to develop.

The National Climate Prediction Center said Pacific water temperatures should remain normal into the summer.

There's a chance an El Nino could develop, which would have the opposite effect of the vanished La Nina. An El Nino occurs when water in the Pacific becomes warmer than normal, increasing the jet stream winds and hampering developing hurricanes.

Seasons with an El Nino usually have fewer storms.

Andrew and Katrina

Seasonal outlooks from the National Oceanic and Atmospheric Administration and the Colorado State University team of William Gray and Phil Klotzbach cite those two weather conditions as the main reasons they expect fewer storms this year.

The outlooks do not try to predict where storms will hit.

Hurricane experts are quick to caution that even a season with fewer than the 16 named storms in each of the past two years is no reason to relax.

The 1992 season brought only six named storms, with three becoming hurricanes.

One of them, however, was Andrew, which ravaged South Florida and was the most costly hurricane to hit the United States until Katrina in 2005.

"Emergency managers do not make any changes in their plans based on a season's forecast," said Dennis Feltgen, spokesman for the National Hurricane Center in Miami.

Change in warnings

This year, the hurricane center is changing its warnings as storms approach land, most significantly how it alerts people about storm surge.

Previously, when the center slotted a storm into a category on the Saffir-Simpson scale, an expected storm surge was attached to each category. A Category 2 storm, for example, was expected to produce a surge of 6 to 8 feet.

But not all storms fit that range.

"A small change in track, size or forward speed can make a huge difference in storm surge," Feltgen said.

In 2004, Hurricane Charley hit Punta Gorda as a Category 4 hurricane, but the surge was only about 6 feet.

In 2008, Hurricane Ike hit Texas as a Category 2 storm, but the surge ranged from 15 to 20 feet.

"After Ike, we heard a lot of people didn't evacuate because it was only a Category 2," Feltgen said.

This year, the hurricane center will describe how high above ground level the storm surge could reach. Look for warnings to include the word "inundation" in the descriptions of surge.

Ten feet of inundation means water will be 10 feet deep, Feltgen said.

There also will be a change in the familiar forecast cone of a hurricane's path. It will be slightly smaller this year, though probably not enough to easily notice on the hurricane center's Web site or maps printed in newspapers.

The cone was shrunk because track forecasts are improving each year. The five-day forecast is now as accurate as the three-day forecast in 1990.