(CNN) -- Tropical Storm Ida churned northward toward the U.S. Gulf Coast on Monday evening, but flooding from the storm's rain bands was already reported in at least one location, hours before Ida was expected to make landfall.
The storm is expected to come ashore sometime Tuesday morning, the National Hurricane Center, based in Miami, Florida, said. The tracking forecast shows making landfall near the Mississippi-Alabama state line.
The governors of Mississippi, Alabama, Florida and Louisiana declared states of emergency as Ida approached and forecasters warned of heavy rainfall.
"Based on the latest information I have seen, Alabama lies directly in the path of Tropical Storm Ida," Alabama Gov. Bob Riley said in a statement. "Though it may not have the force of some of the storms we have dealt with in the past, we cannot afford to take Tropical Storm Ida lightly. The storm surge on the coast and flooding inland pose major threats, which we all must take very seriously."
The city of Dauphin Island, Alabama, reported Monday morning that water was covering a road on the island's west end and advised residents planning to leave to do so before conditions worsened.
Louisiana Gov. Bobby Jindal said that although Louisiana does not appear to lie in Ida's direct path, the potential for flooding remains, particularly in low-lying areas. Authorities were continuing to monitor evacuation routes, he said, in case they need to be used.
As of 10 p.m. ET Monday, the center of Ida was about 100 (165 km) south-southwest of Mobile Alabama.
It was moving north at near 13 mph (20 kph), but was expected to slow down overnight as it approached land.
"On the forecast track, the center of Ida should reach the northern Gulf Coast Tuesday morning," forecasters said Monday.
"After landfall, Ida is expected to turn eastward on Tuesday."
A tropical storm warning stretched across most of the Gulf Coast, from Louisiana to the Florida Panhandle, including the city of New Orleans and adjacent Lake Pontchartrain. A tropical storm warning means that tropical storm conditions including winds of at least 39 mph (62 kph) are expected somewhere within the warning area within 24 hours.
Authorities do not expect New Orleans to receive more water than the city can handle, Jindal said. Workers in some coastal parishes were told to stay home Monday, and some schools were closed. Voluntary evacuations were issued in some coastal parishes, and at least one parish, Plaquemines, had opened a shelter. State officials do not plan to open any state-operated shelters, Jindal said.
Louisiana has offered assistance to other coastal states, as they probably will bear the brunt of Ida, the governor said.
The Coast Guard said it had rescued two crewmen Monday from an oil rig after it was damaged by Ida about 80 miles (130 kilometers) south of New Orleans.
American Airlines said it had canceled 15 flights Monday and 25 Tuesday in cities along the Gulf Coast. Delta Air Lines posted a notice to travelers on its Web site that flights in Gulf Coast cities might be affected.
Escambia County, Florida, said schools and county offices would be closed Tuesday.
"Anyone living on Pensacola Beach, Perdido Key, any other low-lying coastal areas or in a mobile home, in any area of the country, is urged to evacuate beginning Monday," the county said in a statement. Residents were encouraged to stay with family or friends or, "as a last resort, in one of our public shelters."
Ida's winds had dropped to 70 mph (112 kmh), just under hurricane strength, with higher gusts.
"Weakening is expected this evening as Ida moves over cooler waters prior to making landfall," forecasters said. The storm is expected to merge with the incoming frontal zone Wednesday. Tropical storm-force winds extend outward up to 200 miles (320 km) from the center of the storm.
"Rains from Ida are already moving across the coast within the warning area," forecasters said Monday afternoon. The storm is expected to dump between 3 and 6 inches with isolated amounts of up to 8 inches possible in some areas. The rainfall totals are possible through Wednesday morning from the central and eastern Gulf Coast northward into the eastern Tennessee Valley, the southern Appalachians and the southeastern United States. .
In addition, "a dangerous storm tide will raise water levels by as much as 3 to 5 feet above ground level along the coast near and to the east of where the center makes landfall," forecasters said. "Near the coast, the surge will be accompanied by large and destructive waves."
Wind advisories and flood watches were posted as far inland as northern Alabama and Georgia, including the area around the city of Atlanta, which experienced flooding during heavy rains in September.
On Sunday, officials in Alabama's coastal Baldwin County urged residents living in mobile homes, coastal communities or low-lying and flood-prone areas to voluntarily evacuate. The county is also under a local state of emergency and opened a shelter, the county commission said. Baldwin County does not include Dauphin Island, which is in neighboring Mobile County.
Florida's Division of Emergency Management asked residents to have disaster plans in place.
Ida is the Atlantic region's ninth named storm. The Atlantic hurricane season ends November 30.