By David Adams
MIAMI (Reuters) - Meteorologists tracking Hurricane Isaac this week struggled to pin down the vexing storm's next move, variously referring to it as "disorganized" and "uncharacteristic."
For George Dubaz, a New Orleans tour guide, Isaac was simply a "pain in the ass." After two days of lost business he'd had enough of the lumbering Isaac.
"Most of them blow through and are over with. This one is just hanging around too long," Dubaz said, comparing it to "somebody that comes for Mardi Gras and they stay two weeks afterwards."
Plenty of epithets were hurled at Isaac over the last week as it made its way across the Caribbean and up the Gulf of Mexico, barreling into southern Louisiana on the seventh anniversary of Hurricane Katrina.
For those in its path it proved once again the dangers of trying to second-guess a hurricane, even a weak and poorly formed Category 1 storm.
In impoverished Haiti, Isaac tore up flimsy tents sheltering defenseless victims of that country's devastating 2010 earthquake.
Isaac drenched south Florida, disrupting air traffic as well as delaying the Republican National Convention. It chose the seventh anniversary of Katrina to come crashing ashore south of New Orleans, and threatened to burst a dam 100 miles away in rural Mississippi.
The National Weather Service recorded 13 inches of rain in Florida's Palm Beach County, 250 miles from the cyclone's center.
Isaac trailed feeder bands, one reaching 750 miles east of New Orleans that drenched Charleston, South Carolina with 5 inches of rain, producing scenes of kayaking on downtown streets.
Scientists at the U.S. National Hurricane Center are used to dealing with the unpredictability of Mother Nature. But even from a scientific point of view, Isaac was an odd creature, they say. Isaac's behavior was "very uncharacteristic" for a storm of its size, said Todd Kimberlain, 40, a meteorologist at the NHC.
Despite the wide expanse of its tropical force winds that spanned 400 miles at one point, Isaac struggled for days to coil into the tight formation common to powerful hurricanes.
U.S. Air Force hurricane hunter planes were recording alarmingly low pressure inside the storm, typical of an extremely dangerous Category 3 storm and on a par with Katrina. Pockets of dry air and interaction with mountains in Haiti and Cuba hampered its development, Kimberlain said.
NHC advisories constantly warned of the dangers of "life-threatening" flooding from Isaac, and predicted early on it would reach Category 1 status by landfall.
But the slow motion and large size of the storm made its impact more severe and more wide-ranging than many people might have expected from a Category 1 hurricane, NHC officials say, noting that the Saffir-Simpson scale only measures wind strength and not potential for rainfall and storm surge.
People who had prior experience of a weak hurricane might mistakenly have thought they were going to be fine, said NHC director Rick Knabb. "Don't presume that the same good fortune is going to come your way this time. Every storm is different."
Along the Gulf Coast of Mississippi flooding was much worse than expected. "Even though it was a powerful storm, we didn't see this kind of rain with Katrina," said Butch Oberhoff with the Harrison County Emergency Management Agency.
Isaac bore some similarity to Hurricane Irene, which made landfall last year as a Category 1 storm with a broad wind field that caused severe flooding as far away as Vermont.
Kimberlain said he and his fellow scientists were "hard-pressed" to find a comparable storm in recent history. "We couldn't recall one, and normally someone could," he said.
(Additional reporting by Harriet McLeod in Charleston, Emily Le Coz in Tupelo, Scott Malone in New Orleans and Jane Sutton in Miami; Editing by Mary Milliken and Eric Walsh)