The Latest on Tropical Storm Gordon on Monday (all times local):

4 p.m.

Tropical Storm Gordon has left many businesses on Florida's Gulf Coast feeling shortchanged by the holiday weekend.

The Naples Daily News reports that Naples beachfront stores were getting hardly any foot traffic Monday as the storm approached.

The southern Gulf Coast has already been heavily impacted by this summer's so-called "red tide," in which massive algae blooms have caused waves of dead marine life to wash up along the coast, driving people from the water.

At Lowdermilk Park, the beach was nearly empty despite there being no signs of red tide.

Beach Cafe manager Fred Macolino tells the newspaper that business over the holiday weekend had been "horrible."

The storm is expected to move away from the southwestern Florida coast and reach coastal Mississippi and Louisiana by late Tuesday.

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2:20 p.m.

A hurricane watch remains in effects for portions of the central U.S. Gulf Coast as Tropical Storm Gordon approaches.

NOLA.com/The Times-Picayune reports that drivers around the metro New Orleans area are lining up to put sand bags in their trunks. In St. Tammany Parish, a line of cars reached between 20 and 25 vehicles long at times.

The storm was lashing South Florida on Monday with high winds and heavy rains as it moved west-northwest at 16 mph (26 kph).

The National Hurricane Center in Miami said in its 2 p.m. EDT advisory that the storm is expected to move away from the southwestern Florida coast and reach coastal Mississippi and Louisiana by late Tuesday and move inland over the lower Mississippi Valley on Wednesday.

A hurricane watch is in effect for the area stretching from the mouth of the Pearl River in Mississippi to the Alabama-Florida border. A hurricane watch means that hurricane conditions are possible.

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12:30 p.m.

Rain has drenched the Miami area as Tropical Storm Gordon moved into the Gulf of Mexico on Monday.

In a tweet, Miami Beach Police advised residents and visitors that the Labor Day holiday was "NOT a beach day," with rough surf and potential rip currents.

Police advised beach-goers to stay indoors.

In Tallahassee, city officials offered sandbags to help homeowners prepare for potential flooding.

Red flags flew over Pensacola-area beaches in Florida's Panhandle, where swimming and wading in the Gulf of Mexico was prohibited.

The National Weather Service said Naples, Marco Island, and Everglades City also could expect hazardous weather on Monday.

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11 a.m.

A hurricane watch has been issued for portions of the central U.S. Gulf Coast as Tropical Storm Gordon approaches.

The storm was lashing South Florida on Monday with high winds and heavy rains as it moved west-northwest at 16 mph (26 kph). The storm was expected to reach coastal Mississippi and Louisiana by late Tuesday and move inland over the lower Mississippi Valley on Wednesday.

The National Hurricane Center in Miami said in its 11 a.m. EDT advisory that the storm was centered 60 miles (95 kilometers) west-northwest of Key Largo and 50 miles (80 kilometers) south-southeast of Marco Island.

A hurricane watch - meaning that hurricane conditions are possible - was put into effect for the area stretching from the mouth of the Pearl River in Mississippi to the Alabama-Florida border.

A storm surge warning has been issued from Shell Beach, Louisiana, to the Mississippi-Alabama border.

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9:30 a.m.

Residents in parts of South Florida, Mississippi, and Louisiana are being warned to prepare for tropical storm-force winds with the onset of Tropical Storm Gordon. Isolated tornadoes are possible.

The National Weather Service said Monday that Naples, Marco Island, and Everglades City in Florida were among the locations that could expect hazardous weather over the next 36 hours.

The storm is expected to cross from southwest Florida into the Gulf Coast later Monday afternoon.

Flooding was also a high risk for the areas affected by the storm, including portions of southeast Louisiana north of Interstate 10 and southwest Mississippi west of Interstate 55.

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Weather forecasters have issued storm warnings for portions of South Florida and the Florida Keys.

The National Hurricane Center in Miami said Monday that Tropical Storm Gordon is likely to batter the region with heavy rains. A Storm Surge Watch is in effect for a portion of the Mississippi-Alabama border.

The center said in its 8:30 a.m. EDT advisory that the storm was centered 20 miles (30 kilometers) west of Key Largo and 85 miles (135 kilometers) southeast of Marco Island.

The storm was moving west-northwest at 17 mph (28 kph). Maximum sustained winds were clocked at 45 mph (75 kph).