National Hurricane Center
A satellite view of Isaac churning in the Gulf of Mexico.
A satellite view of Isaac churning in the Gulf of Mexico. National Hurricane Center
The National Hurricane Center says that it expects Tropical Storm Isaac to continue strengthening up until it makes landfall.
In the 5 p.m. ET advisory, the Hurricane Center said Isaac remains a tropical storm with maximum sustained winds of 70 mph. Dry air, the center explains, keeps feeding into the storm keeping it from intensifying. The storm is predicted to make landfall near New Orleans as a category 2 hurricane with 100 mph winds.
As the storm comes ashore, the center expects a significant storm surge. Add to that a possible 18 inches of rain and flooding could become a real problem.
The projected track of Tropical Storm Isaac.
The projected track of Tropical Storm Isaac. NHC
Of course, the comparison here is Katrina, because Isaac is on the same general track and is scheduled to make landfall on Katrina's seventh anniversary. The Washington Post's Capital Weather Gang, a sober source for weather news, says that "Isaac is likely to produce hazardous if not dangerous tropical weather in New Orleans."
But the bottom line is that this is not Katrina, which was a monster category 5 storm before weakening and making landfall as a category 3. Here's how Capital Weather Gang sums it up:
"Isaac is simply not the storm Katrina was, but its impact could still be quite large due to the fact it could intensify prior to landfall (whereas Katrina was in a weakening phase). Also, Isaac's forward motion may slow around landfall extending the timeframe the region experiences hurricane conditions relative to Katrina. But, due to the region's better overall preparedness and the storm's lesser size and intensity, Isaac should not pack the same overall punch."
As they reference, after Katrina, Louisiana's levee and flood gate system received an overhaul. The new system should be able to handle a category 2 storm, even with significant rain.
This, however, could be the system's first significant test.
As The New Orleans Times-Picayune reports authorities ordered 70 percent of its flood gates closed. Some of them were closing for the first time since they were built.
But Tim Doody of the flood protection authority said he was confident in the system.
"We don't expect this storm to stress our system," Doody said. "It will be a good test of the system."
Over at Forbes, John McQuaid, who in his former incarnation as a Times-Picayune reporter wrote about the levees, says that a $15 billion rebuilding of the system means a storm of this magnitude "should" be within the system's tolerance.
He says "should" because the it was built by the Army Corps of Engineers, who built the system that failed during Katrina, and compared to other systems in the world, this is a relatively weak one. It is designed to withstand the kind of intense storm that only has a 1 percent chance of happening on any given year. That standard is much stronger than Isaac is expected to become.