Winds from the south on the east side of Nate will open the gates for an influx of deep tropical moisture surrounding the storm over Florida.
Tropical Storm Nate gained strength Friday as it sped toward Mexico's Yucatan Peninsula after drenching Central America in rain that was blamed for at least 21 deaths. Eleven deaths have been reported in Nicaragua, 10 deaths were reported in Costa Rica, and one person was reported killed in Honduras, officials said.
More than 30 people are listed as missing in the three countries. Certain coastal areas of Louisiana outside of levee protections are under mandatory evacuation orders. Forecasters said it was likely to reach the U.S. Gulf Coast over the weekend.
Wind and rain from Nate pounded Grand Isle and Port Sulphur, Louisiana, as the storm, with sustained winds of 90 miles per hour, sprinted toward land at 26 mph.
A state of emergency was declared for 29 Florida counties and states - Alabama, Louisiana and MS - as well as the New Orleans, which was devastated by Hurricane Katrina in 2005.
Since then, Landrieu said, crews have has worked hard to fix the pumps and ensure that the system can withstand the rains, but he warned residents to expect some flooding.
In Louisiana, Mr Edwards mobilised 1,300 National Guard troops, some headed to New Orleans to monitor the fragile pumping system there.
Trump earlier issued an emergency declaration allowing federal aid to be sent to help mitigate the storm's impact.
Louisiana Gov. John Bel Edwards proclaimed a state of emergency for the state Friday morning in anticipation of any severe weather from Nate.
"Nate is expected to make landfall... as a hurricane", the Centre said. Earlier Thursday, a voluntary evacuation was called in the barrier island town of Grand Isle south of New Orleans.
New Orleans officials outlined steps to bolster the city's pump and drainage system. MS officials are providing sandbags in the state's three coastal counties.
Alabama Gov. Kay Ivey issued a State of Emergency Thursday evening in preparation for the storm.
The Pensacola International Airport announced it will close at 6 p.m. Saturday and remain closed on Sunday.
Kessler Air Force Base in Biloxi was not evacuated, officials said.