for National Geographic News
As powerful Hurricane Bertha churns far out in the Atlantic Ocean, meteorologists are wondering why the storm suddenly gathered strength and escalated from a minimal hurricane to a major one in only a few hours.
By around 3 a.m. EDT Monday, Bertha had barely reached hurricane status with winds of about 75 miles (120 kilometers) an hour.
Forecasters at the National Hurricane Center (NHC) in Miami, Florida, predicted that the storm would not intensify much beyond that.
But 12 hours later Bertha's strongest winds had ramped up to 115 miles (185 kilometers) an hour, making it a Category Three storm and the first major hurricane of the 2008 season.
Earlier Tuesday morning, winds had inched up to 120 miles (193 kilometers) an hour, with the center of the hurricane about 1,035 miles (1,660 kilometers) southeast of Bermuda.
What happened to the storm during those 12 hours is a mystery.
"We haven't come up with any explanations," said Richard Pasch, an NHC hurricane specialist.
"We didn't see anything about the environment that looked particularly conducive [to strengthening] at the time. It just underscores the fact that our forecasting of rapid intensification is not very good."
Not Near Land
Because Bertha is so far out at sea, there are no serious consequences to the hurricane's surprise strengthening.
Had the storm been approaching land, however, the unexpected intensification could have set up a tragedy.
"One of our nightmare scenarios is a hurricane that intensifies as it's making landfall," said Max Mayfield, a former NHC director who is now a hurricane specialist for WPLG-TV in Miami.
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