MIAMI, Fla. — Tropical Storm Isaias is continuing its trek across the southern Gulf of Mexico and is expected to strengthen into a hurricane before making landfall along the northern Gulf Coast late Friday or early Saturday, according to the latest advisory from the National Hurricane Center.

As of 7 p.m. CDT Wednesday, the center of Isaias was located about 200 miles west-northwest of Progreso, Mexico, and approximately 480 miles south-southwest of the mouth of the Mississippi River. The storm was moving east-northeast at 8 mph with maximum sustained winds of 65 mph and a minimum central pressure of 994 millibars.

Forecasters say Isaias is expected to become a hurricane by Thursday morning, with additional strengthening possible through Friday morning. The storm is forecast to pass north of the Yucatán Peninsula on Thursday before turning northeast and north toward the U.S. Gulf Coast.

Hurricane and storm surge watches are already in effect across portions of the northern Gulf Coast as communities prepare for the potential impact.

A Hurricane Watch has been issued from Bay St. Louis, Mississippi, to Indian Pass, Florida. A Storm Surge Watch remains in effect from the mouth of the Mississippi River eastward to Yankeetown, Florida, while Tropical Storm Watches extend across portions of Louisiana, Mississippi, and Florida's Big Bend region.

Emergency officials warn that storm surge could pose the greatest threat to life and property. Current forecasts call for:

5 to 7 feet of storm surge from Ocean Springs, Mississippi, to Indian Pass, Florida
5 to 7 feet in Mobile Bay
3 to 5 feet from the mouth of the Mississippi River to Ocean Springs
4 to 6 feet from Indian Pass to the Steinhatchee River
2 to 4 feet from the Steinhatchee River to Yankeetown
1 to 3 feet in Lake Pontchartrain

The National Hurricane Center warns that the highest water levels will occur near and east of the eventual landfall location, where dangerous waves will accompany the surge.

Heavy rainfall is also expected across the Gulf Coast and Southeast. From Friday through the weekend, Isaias could bring 3 to 7 inches of rain, with isolated totals reaching 10 inches from southeastern Louisiana through the Florida Panhandle. Additional rainfall of 1 to 3 inches, with localized amounts up to 5 inches, is possible across parts of the Southeast, including portions of the Tennessee Valley and the Carolinas.

Meteorologists caution that flash flooding, urban flooding, and isolated river flooding may develop as the storm moves inland.

The threat of tornadoes is also increasing. Forecasters say tornadoes could begin developing Friday evening along the northeastern Gulf Coast as outer rain bands move ashore, with the risk spreading inland Saturday as Isaias advances northward.

Meanwhile, residents along the Gulf Coast are being advised to monitor dangerous surf and rip current conditions. Swells generated by Isaias are expected to affect the Yucatán Peninsula on Thursday before spreading northward across Gulf Coast beaches later this week.