NEW ORLEANS (AP) - New Orleans Mayor LaToya Cantrell says the city's Treme neighborhood got 8.4 inches of rain in three hours, and more nasty weather is on the way.

  

Cantrell has declared an emergency. She and other officials spoke at a news conference Wednesday after storms swamped city streets and paralyzed traffic.

  

Numerous officials urged residents to stay home, check that they have supplies for at least three days and make sure neighborhood storm drains are clear.

  

National Weather Service meteorologist Benjamin Schott says a hurricane hunter aircraft was going to look for the center of the developing tropical cyclone in the Gulf of Mexico. He says the aircraft will provide information about its likely landfall.

  

Schott says storm surge could raise the Mississippi River to 20 feet , adding, "That's not what we'd consider worst-case."