The 4 p.m. update from the National Hurricane Center is in, and it shows that Tropical Storm Isaac is gaining strength, but is still just below hurricane status.
The eye of the storm is now 320 miles south-southeast of Mobile, moving northwest at 12 miles per hour with maximum sustained winds of 70 miles per hour. The minimum for a hurricane is 72 m.p.h., and the NHC expects Isaac to reach that level this evening. A top wind speed of about 100 m.p.h. is expected at landfall.
Landfall is still expected to come in southeast Louisiana, with New Orleans directly in the projected path. Landfall should come late Tuesday night or early Wednesday morning. The path continues to be shifted toward the west, with the new projection taking the eye near Monroe, La. by midday Thursday. That change moves the storm farther away from central Alabama, and may mean that metro Birmingham may escape Isaac with little more than a good rain and moderate winds. Because the storm is slow-moving, though, that rain could last for two or three days, beginning Wednesday and going through Friday.
The hurricane warning area has now been pulled in a bit to the west, with the warning now extending only as far as the Alabama-Florida border. The area from there east to Destin is now under a tropical storm warning. The NHC forecasts a storm surge between six and nine feet along the Alabama coast.