Hurricane Isaias: At least 4 dead as Isaias downgraded to post-tropical cyclone

Flash and urban flooding will remain likely across the region, with considerable impacts possible across much of southern Alabama and the Florida Panhandle into southwestern Georgia as well as for parts of southern Appalachia and the coastal Carolinas.

River flooding is also expected, some of which could be significant.

Severe storms are also a concern for these areas. A level 2 of 5 “slight risk” for severe weather is up from Tallahassee, Florida, to Columbia, South Carolina, for severe storms from Isaias’ outer bands. Damaging winds and tornadoes are possible with these storms later Saturday.

The heaviest rain will be over the coastal Carolinas and southern Appalachia later Saturday, with light rain beginning to spread into Indiana and West Virginia.

More rain is expected to move through the mid-Atlantic Sunday morning and through the Northeast later in the afternoon.

-ABC News' Kyle Reiman

At 2 a.m. ET, the National Hurricane Center declared Isaias a post-tropical cyclone -- a system that no longer possesses characteristics of a tropical system.

More than a foot of rain has fallen so far in parts of Georgia and Florida from Isaias, including 12.97 inches in Bellwood, Alabama, 12.47 inches in DeFuniak Springs, Florida, 11.63 inches in Graceville, Florida, and 10.01 inches in Elba, Alabama.

As of the latest update from the National Hurricane Center, Isaias is over southern Alabama with maximum sustained winds of 35 mph and is moving north at 14 mph.

Since Isaias has weakened to below tropical storm strength, all storm surge and tropical storm alerts have been discontinued. However, wind advisories remain up across much of the region for sustained winds of 20 to 30 mph with gusts up to 50 mph possible through Sunday morning.

-ABC News' Kyle Reiman

At least 800,000 customers in Florida, Alabama and Georgia are currently without power Saturday morning as Hurricane Isaias made landfall near Destin, Florida, in the Florida Panhandle on Friday night.

As of 3:39 a.m. ET on Saturday, at least 445,000 are without power in Florida, with an estimated 309,000 in Alabama and 50,000 in Georgia also without power in the hurricane zone.

-ABC News' Michael O'Keefe

Hurricane Isaias continued its march north over the western Florida Panhandle on Friday night, although it weakened to a Category 1 storm, the National Weather Service said.

Maximum winds were at 90 mph and it was moving at 20 mph, the NWS said.