Hurricane watch issued; Isaac drifts westward

A hurricane watch is now in effect for the area between the mouth of the Mississippi River and the Mississippi-Alabama line, as a strengthening Tropical Storm Isaac’s path has shifted westward, closer to Mobile Bay.

National Weather Service forecasters also are forecasting the storm to be a Category 2 hurricane at its U.S. landfall.

By issuing a hurricane watch, forecasters are confirming that hurricane conditions — sustained winds of 74 mph or higher — are possible in the specified area. Because preparation becomes more difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.

Tropical storm force wind probabilities now range from 60-70 percent for the Mississippi Gulf Coast, and hurricane force wind probabilities are now 10-20 percent.

Isaac has strengthened slightly, but still lacks thunderstorms near the center. A large rain area to the north of center was expanding North and West.

The entire Mississippi Gulf Coast is now within the cone of uncertainty. Some of the model guidance continues to indicate a shift more to the west, which could mean adjustments to the track in the next few advisories.

The detailed briefing: To see the 4 a.m. local briefing from the National Weather Service Slidell office, click here.

More info: For live radar and updated coordinates, visit the city’s online Storm & Flood Preparedness center by clicking here.