Isaac is a large storm in terms of surface area with its circulation extending out hundreds of miles from the center, especially on its eastern and northern side.
Isaac is a fast-moving storm at present. Nasty conditions and water rises are likely to occur quickly, as the center approaches the coast Tuesday afternoon and moves inland Tuesday evening.
People are urged to speed necessary preventative measures on their property and evacuate if told to do so by officials. Some low-lying roads and communities could be cut off by rising surf and storm surge. Isaac will bring flooding, downed trees and power outages at the very least in portions of Louisiana, Mississippi and Alabama. Outer bands from the storm, essentially severe thunderstorms can still cause damage and disruptions over portions of Florida.
With a storm moving in from this direction, winds in the wake of the storm over the Lake Pontchartrain area would be from the west, southwest and south, tending to pushing water away from the shores of New Orleans.
Recall that during Katrina, southeast winds drove water into Lake Pontchartrain initially. And, that is likely to happen again with Isaac to some extent. However, due to the south to north path of the Katrina, north to northwest winds drove the elevated lake water toward the city, contributing to levee failure.
"Isaac is large, but not an exceptionally healthy tropical storm," Kottlowski stated. "Isaac continued to struggle with dry air entrainment and wind shear Monday midday."
Despite Isaac's current struggles, the combination of warm Gulf waters and lowering wind shear into Tuesday could lead to strengthening prior to landfall. "People along the Louisiana, Mississippi and Alabama coasts need to take the threat from Isaac seriously," Kottlowski said. "It is better to be safe than sorry."
As a precaution petroleum rigs in the central and northeastern Gulf of Mexico were being shut down and evacuated.
Alex Sosnowski is Senior Expert Meteorologist for AccuWeather.com. Images are from AccuWeather