FORT LAUDERDALE, Fla. _ It's the weather, so it doesn't always do what people think it might.
That was the case with now-Tropical Depression Karl on Wednesday, which instead of strengthening as expected, thumbed its nose at high-tech forecasting tools and weakened to a tropical depression.
But the weakening was thought to be temporary. Karl, which on Wednesday afternoon was about 800 miles southeast of Bermuda and not a threat to the U.S., was still expected to become a hurricane, only later than originally anticipated.
"Our earlier forecast did show Karl strengthening more quickly than it necessarily has," said Michael Brennan, a senior hurricane specialist at the Miami-based National Hurricane Center.
"We are still forecasting it to become a hurricane as we get later into the week," Brennan said.
According to another forecaster at the hurricane center, global forecasting models "totally failed" when it came to winds surrounding the storm.
Because wind shear _ which blows storms apart _ had been expected to weaken, Karl in turn had been expected to keep strengthening.
However, as of Wednesday, that wind shear was still strong, which meant Karl had lost steam.
"Global models have totally failed so far in forecasting the upper-level winds surrounding Karl," senior hurricane specialist Lixion Avila wrote in a 5 a.m. Wednesday morning discussion posted on the hurricane center's website. "The upper-low near Karl which unanimously all models have been forecasting to weaken is still strong and producing shear over the cyclone."
As of Wednesday at 5 p.m., Karl's maximum sustained wind speeds were 35 mph, below the 39 mph threshold for a tropical storm.
Expected to pass near Bermuda on Saturday on a boomerang-shaped path, Karl was forecast to be a hurricane by Saturday afternoon. It was expected to remain a hurricane on Sunday as it continues on a northeast path toward the North Atlantic before diminishing Monday to a tropical storm.
Brennan said any predictions of how intense the storm would be were complicated by differing forecast models of the direction of the wind shear and the amount of moisture in the air around the storm.
"We're getting mixed signals from the models about what the environment is going to be for the storm," Brennan said.
"There's always lots of uncertainty," Brennan added.
Meanwhile, Tropical Storm Lisa, which also wasn't a threat to the U.S., was moving northwest in the far Atlantic. Its maximum sustained winds were 45 mph on Wednesday afternoon, and it was expected to start weakening on Thursday and be a tropical depression by Friday, according to the hurricane center.
Beyond Karl and Lisa, the Atlantic wasn't expected to churn out any new storms in the next few days.
"We don't have anything in our outlook for the next five days at this point," Brennan said.
