>>> the word "storm" and "new orleans" in the same sentence, it's easy to think the worst. six years after hurricane katrina did unthinkable damage to that city, tropical storm lee, a slow-moving system, has been dumping rain for days, swelling rivers and bayous, prompting flood warnings in several areas of louisiana and putting new orleans on high alert. tonight, there are reports of spinoff tornadoes in neighboring alabama and mississippi. but the good news, this is not a hurricane and the levees in new orleans appear to be holding firm. nbc's tan t troung is in louisiana with more.

>> reporter:  this is the fourth straight day with gusting winds and rain for the city of new orleans. this storm is a slow, massive rain-maker and is still not finished. tropical storm lee's most potent punch, persistent rain. from louisiana all the way to the florida panhandle, lee is predicted to dump up to 20 inches of rain in some areas.

>> it comes in fast. and there's nothing to hold it back.

>> reporter:  john didn't heed the mandatory evacuation order for his neighborhood in lafitte, louisiana. the low-lying town is seeing some of the heaviest flooding.

>> whatever happens, happens. i mean, we can't do anything about it.

>> reporter:  further out, oil rigs in the gulf of mexico shut down and evacuated workers ahead of landfall. but lee's slow slog across the gulf states isn't packing much of a storm surge. new orleans is welcoming that news.

>> this event is not testing the levees, it isn't. there's not much of a surge concern here.

>> reporter:  the biggest concern here is the deluge. more than half of new orleans sits below sea level. the city's survival depends on an intricate system of pushes and levees. this pump station is one of three quickly built after hurricane katrina. they'll help drain the same canals that flooded and eventually breached the levees back in 2005.

>> unlike the northeast united states, we cannot drain water by gravity. we're not going to flow downhill. in new orleans, we have to pump it up and over the levee system.

>> reporter:  the pumps so far are keeping new orleans relatively dry. that's enough reason to celebrate for a city that never needs an excuse to party.

>> we love it.

>> reporter:  clinton and courtney are here for their hon noon.

>> they always say it's good luck to have rain on your wedding day and it rained all day on our wedding day. so lots of luck.

>> reporter:  with no reported fatalities or widespread damage. lucky is how many are feeling tonight. and city leaders warn against getting too complacent. we're expecting more rain for the next 24