Hurricane Marco forms off the Gulf Coast as Tropical Storm Laura is close behind

Tropical storm Marco was upgraded to hurricane status on Sunday as it gained strength over the Gulf of Mexico. Marco could be part of an unprecedented twin strike to the U.S. Gulf Coast alongside Tropical Storm Laura, which could also strengthen to a hurricane this week.

Marco entered the Gulf of Mexico Saturday evening and was headed toward landfall in Louisiana or Mississippi on Monday afternoon, according to National Hurricane Center projections. As of Sunday afternoon, the Air Force Reserve Hurricane Hunter found Marco had reached sustained winds of 75 mph.

To reach hurricane status, a storm needs to generate sustained winds of at least 74 mph.

The National Hurricane Center in Miami warned Marco is expected to bring high gusts and life threatening storm surge along the Gulf Coast.

Tropical storm Laura — about 40 miles northeast of Port au Prince, Haiti, as of Sunday morning — was expected to strengthen to a hurricane by Tuesday afternoon, the center said. It could make landfall from Texas to Florida's Gulf Coast by Wednesday afternoon, forecasters said.

"It looks like the upper Gulf is going to get a one-two punch," hurricane center spokesman Dennis Feltgen said. "That’s pretty much unprecedented that close together."

The shortest time between U.S. landfalls for major storms is 23 hours between Sept. 4 and 5, 1933.

4PM Marco Update: Forecast to parallel the Louisiana Coast Tuesday and move into SE Texas Late Tuesday as a weak tropical storm. https://t.co/glMKXjP5mZ #12NewsNowWeather pic.twitter.com/OfeMLBEl6d

— Patrick Vaughn (@PatrickVaughn4) August 23, 2020

Louisiana Gov. John Bel Edwards declared a state of emergency Friday ahead of the storms and on Saturday asked President Donald Trump to grant federal emergency status to the state.

"Tropical Storms Marco and Laura are forecast to impact Louisiana in quick sequence early next week," Edwards' office said in a statement.

A mandatory evacuation of Plaquemines Parish in New Orleans will begin on Sunday afternoon, parish officials announced on Saturday night. Plaquemines is the southernmost area of the city, surrounded by the Gulf of Mexico, and has been severely damaged by previous hurricanes, including Katrina in 2005.

Marco was in the Gulf of Mexico, about 360 miles southeast of the mouth of the Mississippi River, according to the hurricane center on Sunday morning. It was moving north-northwest at 13 mph.

A hurricane watch was in effect from Intracoastal City, Louisiana, to the Mississippi-Alabama border, including New Orleans, federal forecasters said.

Tropical Storm Laura had maximum sustained winds of 45 mph as of Sunday, moving west at 18 mph.

A tropical storm warning was in effect for Puerto Rico, the U.S. Virgin Islands and parts of the northern coast of the Dominican Republic and a tropical storm watch was issued for the central Bahamas and the Florida Keys from Ocean Reef to Key West and the Dry Tortugas, the hurricane center said.