Say "hurricane" and "Gulf Coast" is more likely to come to mind than the "East Coast." Earl has obviously altered that way of thinking for now, but what's not as obvious are the distinct differences between the two regions when it comes to storm impacts. We're talking differences in shoreline topography, population, infrastructure and even storm speeds.
Frank Lepore, a spokesman for the Federal Emergency Management Agency and prior to that a National Hurricane Center spokesman, has seen it from both ends: the forecasting and then the impacts. And it's very clear in his mind how distinct the coasts are.
"The Gulf of Mexico generally has a very long sloping bottom," Lepore notes. And that makes for a stronger surge when a storm pushes water ashore. During Katrina, he adds, parts of Mississippi saw a 20-foot surge of water.
The East Coast, on the other hand, generally is steeper, making it harder to push water onto land. Still, that doesn't mean a small surge can't do damage. North Carolina's Outer Banks, the area most vulnerable to Earl right now, regularly see 3- to 5-foot surges from small storm systems that overtop parts of the state highway running through the barrier islands.
The Gulf's population is around 15 million. Compare that to the Mid-Atlantic states at 57 million, and New England at 14 million.
Apart from the logistics of dealing with millions more people, there's the differences in "collective memory" among Gulf and East Coast populations, Lepore says. Gulf residents, more accustomed to hurricanes, "tend to remember" the danger when evacuations are ordered, he adds. "New England doesn't have that historical component." Indeed, the last hurricane was Bob back in 1991, when 18 people were killed.
Hundreds of oil rigs sit in the Gulf, and any threat triggers a well-practiced routine of production closures and crew evacuations, Lepore says.
The East Coast doesn't have that problem, but it does have lots of trees — think downed power lines and blocked roads. So even if most of the East Coast sees just tropical storm-force winds from Earl, Lepore says, "it doesn't take much to gum up the works."
• Storm speeds
Storms move faster at higher latitudes, Lepore notes, so that means the East Coast sees systems move through much faster than in the Gulf.
An East Coast storm typically "does not linger" because it's often racing along at 35 mph at northern latitudes, Lepore says. "It's not dropping a lot of rain" the farther north a storm goes and the faster it moves. Often it doesn't even hit land, instead moving along the coast offshore.
Along the Gulf, on the other hand, "it's gonna make landfall."