Isaac forecast to a Cat 1 hurricane at landfall with a max wind of 90 mph near the center. But the concern is that with the track being shifted ever westward it may have more time over warmer water allowing it to reach Cat 2 or Cat 3 major status. However, Isaac has thus far defied expectations.
The latest GFS model guidance forecasts a landfall Wednesday morning just west of Morgan City. The European model guidance forecasts a landfall just west of Gulf Port, Mississippi Wednesday morning. The Canadian model forecasts a landfall right on the Louisiana-Mississippi state line right midday Wednesday. Finally, the consensus model guidance puts Isaac inland right over or near the mouth of the Mississippi River and just southwest of New Orleans late Tomorrow night.
So it looks like landfall possibly close to New Orleans between Gulf Port, MS and Morgan City, LA after midnight Tuesday night-Wednesday morning. Environmental conditions are expected to be favorable from through Tomorrow and strengthening is likely so Isaac should be a Category 2 hurricane with max winds near the center around 100 mph. The forecast track is not a lock though so it may need to be adjusted again. After landfall the hurricane prediction center sees it going North to West Tennessee Friday and Southwest of Saint Louis Saturday, but I think a track more toward Texas is just as possible.
Storm Surge Impact: Southeast Louisiana, the Mississippi coastline & the Alabama coastline: 6 to 12 Feet. South-Central & Southwestern Louisiana: 3 to 6 Feet.
The Florida Panhandle: 3 to 6 Feet.
Wind: Tropical Storm force winds will overspread the northern Gulf coast from Louisiana to the Florida Panhandle by this evening with tropical storm conditions expected throughout the night tonight. On Tuesday, hurricane force winds are expected to overspread areas from southeastern Louisiana to the Mississippi and Alabama coastlines during Tuesday afternoon with hurricane conditions continuing across this area throughout Tuesday night and into Wednesday morning. Isolated brief weak tornadoes possible inland.
Rainfall: Additional rainfall amounts of 2 inches are expected today across central and south Florida. Total rainfall amounts of 6 to 14 inches with isolated amounts of 20 inches is expected from Tuesday through Thursday across southeastern Louisiana, southern Mississippi, southern Alabama and the western Florida Panhandle. Flooding is a major threat to New Orleans, more than the wind.
For Atlanta: Our breeze and humidity will be on the increase the next few days as we feel the indirect circulation around Isaac, and it will bring scattered showers and thunderstorms tomorrow into Friday, but flooding is not expected at this time but some areas could accumulate 1-3 inches of rain by Saturday.