Tropical Storm Gordon heads toward Gulf Coast

(CBSNews) -- A storm system moving quickly toward the central U.S. Gulf Coast strengthened to a tropical storm early Monday, according to the National Hurricane Center. Tropical Storm Gordon, located about 20 miles west of Key Largo, Florida, is moving west-northwest at 17 mph. Maximum sustained winds Monday morning were clocked at 45 mph.

As of 8:30 a.m. ET tropical storm warnings were issued for portions of South Florida (from Golden Beach to Bonita Beach), and for the Florida Keys (from Craig Key to Ocean Reef), including Florida Bay. This was in addition to warnings already posted from the Alabama-Florida border through Biloxi and New Orleans, towards the central Louisiana coastline, including Lake Pontchartrain and Lake Maurepas.

Meteorologist Danielle Niles of CBS' Boston station WBZ says the threat along the Gulf Coast means heavy rain as well as storm surge. 

The National Weather Service says Gordon is expected to pass over the Florida Keys and the southern portion of the Florida peninsula Monday morning, reaching the central Gulf Coast by late Tuesday or Tuesday evening.

The system could dump 2 to 4 inches of rain over parts of the Bahamas, the Florida Keys and South Florida through early Tuesday.

Storm surge may each 2 to 4 feet from the Mississippi-Alabama border to the mouth of the Mississippi River.

The storm threat comes amid major flooding in the Midwest, due to a slow-moving storm that has brought flash flood watches and warnings from Kansas to Nebraska, stretching to portions of Iowa and northern Illinois.

Meanwhile, Tropical Storm Florence continues to hold steady over the eastern Atlantic, about 790 miles west-northwest of the southernmost Cabo Verde Islands.

Florence was moving toward the west-northwest near 16 mph and maximum sustained winds of 50 mph with higher gusts late Sunday evening.

Forecasters say little change in strength is expected in coming days and no coastal watches or warnings are in effect.