7.15.2008 8:07 AM

Bertha Could Re-Gain Hurricane Strength

Long-lived and Surprising, Bertha Lives On Nearly 2 Weeks After Forming

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By July 15, Tropical Storm Bertha was turning east toward the open Atlantic and moving away from Bermuda. With maximum sustained winds of 70 mph, Bertha remained a strong tropical storm nearly two weeks after first forming off the coast of Africa. Forecasters said Bertha could regain hurricane strength.

Photo: NOAA

By Dan Shapley

Bertha may have lost hurricane strength only long enough to brush by Bermuda, where it knocked out power to thousands but apparently caused no injuries or death.

The second named storm of the Atlantic hurricane season has proved surprising and perplexing as it slowly moves through warm Atlantic waters. Its long life may not bode well for the rest of the tropical storm season, which typically peaks in a month or two.

Tropical Storm Bertha could re-gain hurricane strength within a day, according to the latest report from the National Hurricane Center.

Tropical Storm Bertha formed on July 3 and grew into a hurricane (then quickly a major Category 2 hurricane) July 7, and its strength fluctuated before losing strength over the next several days. As a tropical storm, she brought strong winds and rain to Bermuda, and strong surf as far as the U.S. East Coast July 14, but has otherwise not affected land or people.

The first tropical storm of the Atlantic season, Arthur, brought punishing rains to parts of Central America June 1, right in time for the official start of the hurricane season. The peak of activity most years occurs in late summer.

Hurricane Bertha's formation followed an active period in the eastern Pacific Ocean, where three tropical storms and the first hurricane of the eastern Pacific season, Hurricane Boris, formed within days of each other last week. Monday, a tropical storm in the eastern Pacific grew into Hurricane Elida, the third hurricane of the season and second in the eastern Pacific. Tuesday, Elida continued to move westward away from land.

The forecast from the government's Climate Prediction Center says it's likely that 2008 will be an active year for hurricanes in the Atlantic basin, which includes the Caribbean, but not the Pacific. There's a good chance we'll see 12 to 16 named storms, including six to nine hurricanes and two to five major hurricanes (Category 3, 4 or 5 on the Saffir-Simpson Scale). Average is 11 named storms including six hurricanes, two of them major storms.

Last season did not produce the predicted number of storms. There were more named storms but fewer hurricanes than predicted. Those hurricanes that did form intensified rapidly before landfall, and the first-ever record of back-to-back Category 5 landfalls came when Hurricanes Dean and Felix hit Central America. (The names Dean and Felix, along with Noel, a weaker but deadly 2007 Caribbean storm, have been retired.)

The last several months have seen a flurry of science related to global warming and hurricanes. A longtime proponent of the idea that warmer ocean temperatures will produce stronger storms, Kerry Emanuel, has called that hypothesis into doubt. But the government has said that warmer oceans will produce fewer, but stronger storms in the coming decades. The jury, it seems, is still out, as scientists study the complex forces that influence hurricane behavior.

This year, a lingering La Niña (cool pattern) in the Southern Pacific, warmth in the tropical Atlantic, and the strong-phase of a multidecadal storm activity cycle are expected to be driving forces behind an active storm year.

2008 Tropical Storms and Hurricanes - Atlantic

Tropical Storm Arthur formed quickly on May 31 off Belize and lost tropical storm strength in fewer than 24 hours, amd brought punishing rains of 10-15 inches to parts of the Yucatán Peninsula, including Mexico and Guatemala.

tropical storm arthur
NOAA

Hurricane Bertha after forming as a tropical storm July 3 in the far eastern Atlantic, Hurricane Bertha debuted as the Atlantic's first hurricane July 7 and quickly grew to major hurricane status. By the time it affected land, July 14 in Bermuda, it was a strong tropical storm, causing rough surf and threatening 3-5 inches of rain, but forecasters said it could re-gain hurricane status after passing the island.

hurricane bertha
NASA