Storm Diary: Hurricane Bertha (Update)

Tropical Storm Bertha formed out of a tropical depression in the far eastern Atlantic, near the Cape Verde Islands, on July 3, 2008. It was the second named storm in what has been forecast to be an active hurricane season.

The first hurricane of the 2008 Atlantic season, Hurricane Bertha formed early on July 7 in the distant Atlantic, hundreds of miles from the nearest land, the northern Leeward Islands. It was a weak Category 1 hurricane at the time, and forecasters couldn't then say whether it would strengthen or make landfall.

Hurricane Bertha remained far from shore as it formed and gained strength July 7, but forecasters predicted at the time that the Atlantic season's first hurricane could approach Bermuda within days.

Within hours, Hurricane Bertha had gained 20% in strength, and forecasters predicted it would continue to grow in strength. By the end of its first day, Hurricane Bertha was not only the first hurricane of the 2008 Atlantic season, but the first major hurricane, as defined by its wind speed.

Hurricane Bertha became the longest-lived tropical storm ever to ply the Atlantic, and her 16-day lifespan was a result of warm waters.

This early July map shows sea-surface temperature, a key precursor of hurricane intensity, with the darkest oranges showing water at about 77 degrees (F).

Hurricane Bertha grew into a major hurricane late on July 7 and retained Category 3 strength July 8. It looked increasingly unlikely, however, that Bertha, with her 120 mph sustained winds, would make landfall, as the storm churned 1,000 miles southeast of Bermuda.

Map showing projected track of Hurricane Bertha in the Atlantic Ocean as of July 8, 2008.

On July 3, Tropical Storm Bertha formed in the far eastern Atlantic, became a hurricane on July 7 and reached its peak intensity on July 8 as a Category 3 storm. She was the first hurricane of the 2008 Atlantic season, and a rare major hurricane in the month of July.

While Bertha lost hurricane status before drenching Bermuda July 14, she regained hurricane strength again July 18.

By the time Bertha dissipated July 20, she was the longest lived tropical storm on record for the Atlantic in the month of July, and she contributed to the third most active July, in terms of accumulated cyclone energy.

This image is from July 9.

After having lost major hurricane status the day before, a resurgent Hurricane Bertha grew back into a Category 2 storm July 10, 2008. There was a better than 40% chance that tropical storm-force winds from Bertha would affect Bermuda.

On July 11, Hurricane Bertha was near enough to Bermuda that the first tropical storm warnings for the week-old storm were issued. It remained a Category 1 hurricane, and had about a 50% chance of unleashing tropical storm-force winds on the island.

On July 11, 2008, the first tropical storm watch was issued for Bermuda, as Hurricane Bertha moved near enough to menace the island. This chart shows the probability of tropical storm-force wind affecting different areas, with green representing a 5% chance and purple a 100% chance.

By Monday, July 14, 2008, Hurricane Bertha had been downgraded to a strong tropical storm, but her winds were beginning to whip up swells and rough surf in Bermuda, where 3-5 inches of rain was predicted.

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.

By July 18, Tropical Storm Bertha had become the longest-lived tropical storm ever recorded in July in the Atlantic. It formed on July 3, and was still churning 15 days later. Forecasters said it could retain tropical storm strength until about July 20.

After nearly a week as a tropical storm, and 15 days into its life, Bertha grew back into a hurricane July 18. She is by far the longest-lived tropical storm ever recorded int the Atlantic during the month of July. Bertha lost strength on July 19 and soon dissipated, leaving behind only her name in the annals of storm history.

Both Tropical Storm Bertha's long life and, during the period when she had hurricane status, strength were anomalous. Typically, the peak of hurricane season, when major hurricanes develop, is in the late summer and into the early fall.