Sally rapidly intensified to Category 2 hurricane Monday, edging toward the coastline of Louisiana, Alabama and Mississippi, where it is forecast to push ashore a “life-threatening” surge of up to 11 feet and unload tremendous rainfall through Wednesday.

The storm is slowly crawling west-northwest toward the Gulf Coast and its assault on the coast will be prolonged. Before landfall between Tuesday and Wednesday, Sally may intensify further over the warm waters of the Gulf of Mexico.

While its strong winds will get plenty of attention, potentially bringing 70 to 100 mph winds between the coasts of southeast Louisiana and Alabama, this storm’s greatest threat is water. This part of the Gulf Coast is extremely vulnerable to storm surge flooding, which refers to the storm-driven rise in water above normally dry land at the coast.

Due to its slow forward speed as it approaches the coast, heavy rains will deluge areas from southeast Louisiana to the Florida Panhandle with excessive rainfall, up to two feet in some areas. This could cause widespread, major flooding, and if heavy downpours continue for many hours in New Orleans, they could challenge the capacity of the city’s pumping system.

Here are some significant developments:

  • Sally intensified from a strong tropical storm Monday morning into a 100 mph Category 2 hurricane as of 8 p.m. eastern. Additional strengthening is possible with winds forecast to peak around 110 mph prior to landfall.
  • The storm track shifted slightly east on Monday, with landfall projected now projected over coastal Mississippi rather than southeast Louisiana. Hurricane warnings were extended east over the western Florida Panhandle.
  • The timing of landfall is more uncertain than usual, but is currently projected for Tuesday night into Wednesday morning.
  • Tropical storm conditions are expected to develop Monday night or early Tuesday morning in coastal Alabama, Mississippi and southeastern Louisiana.