A dangerous cyclone spinning toward the Gulf Coast intensified Thursday to become Tropical Storm Barry.
It's the first tropical storm to threaten the US this year. But before Barry makes landfall -- possibly Saturday in Louisiana -- it'll likely be a full-blown hurricane, meaning winds will top 74 mph.
But it's not the wind that makes this storm so treacherous. It's the colossal rainfall and massive storm surges.
Streets in New Orleans have already turned into lakes after the storm's outer bands pummeled the city with up to 9 inches of rain.
And it'll only get worse.
As of 11 a.m. ET, Barry was hurling sustained winds of 40 mph in the Gulf of Mexico, the National Hurricane Center said.
But because Barry is a slow-moving storm -- crawling across the Gulf at just 5 mph -- the system will hover over the same places for a long time, dropping relentless rain and adding to the widespread flooding.
In Grand Isle, Louisiana, the mayor and town council ordered everyone to evacuate Thursday.
"We are expecting a rain fall total that can range from 6" to 10"," they said in a statement. "We will be experiencing unusual high tides that will range more than 3 feet above ground."
Torrential rain and flooding are the biggest threats
Southern Louisiana, Mississippi, Alabama and the western Florida Panhandle are under the gun for extreme rainfall Thursday, CNN meteorologist Haley Brink said.
And storm surge on the coast could be "life-threatening," the National Hurricane Center said.
The rain and storm surge will cause the Mississippi River to swell to dangerous levels. The Mississippi River could crest at 20 feet in New Orleans, or 1.3 feet below the record. The city is only protected to a height of 20 feet.
In preparation for the onslaught, Louisiana officials have started closing flood gates. The Southeast Louisiana Flood Protection Authority has about 250 flood gates, spokesman Antwan Harris said.
More than 200 flood gates in New Orleans and St. Bernard parishes are expected to be closed by Friday, local media reported.
New Orleans suffered the wrath of the storm's outer bands Wednesday, when up to 9 inches of rain submerged entire neighborhoods under water.
Resident Dannie P. Davis said she's seen enough and is ready to go. She just doesn't know where yet.
"I am evacuating. The water levels ... were too high for my comfort, and my car nearly flooded," Davis told CNN on Thursday.
"I haven't seen this much rain and flooding before a hurricane in a while. While the evacuation isn't mandatory, I am leaving as a precaution. Who knows what's to come, how and whether the city will able to handle it."
Governors say get ready now
Louisiana Gov. John Bel Edwards warned "no one should take this storm lightly," as 10 to 15 inches of rain could fall within 24 hours between Friday and Saturday.
He declared a state of emergency and urged residents to have a contingency plan for family and pets.
"This is going to be a Louisiana event with coastal flooding and heavy rainfall potentially impacting every part of the state," Edwards said.
And just because the storm might max out as a Category 1 hurricane doesn't mean it won't be destructive. Hurricane categories only denote maximum sustained wind speeds, not rainfall or other factors.
"As we know all too well in Louisiana, low intensity does not necessarily mean low impact," the governor said.
In Texas, Gov. Greg Abbott told residents to make plans now.
"Begin preparing your property, your supplies, your lines of communication to your family members," Abbott said. "Begin preparing to know exactly where you need to go if you need to evacuate."
This storm could affect gas prices
Even if you live far from the coast, you could still get hit by the storm in terms of gas prices.
The tropical system is swirling near many of the oil rigs in the Gulf of Mexico. Offshore oil and gas operations in the Gulf are evacuating their facilities, the Bureau of Safety and Environmental Enforcement said.
The companies have evacuated employees from 15 production platforms and four rigs so far. Three of the 20 rigs operating in the Gulf have also moved out of the path of the storm, it said.
Unlike drilling rigs, which typically move from location to location, production facilities stay in the same spot throughout a project's duration.
And even days before landfall. US oil rose above $60 a barrel on Wednesday amid worries that the storm system could derail crude production in the Gulf of Mexico.