The tropical depression meteorologists have been watching for days was upgraded to a storm and named Bonnie Saturday about 5 p.m., according to the National Hurricane Center.

A tropical strom warning was issued at 4:50 p.m. Friday for the entire South Carolina coast from Georgia to North Carolina.

The difference in categories depends on the wind speed:

Tropical Depression – wind speed less than 39 MPH

S: Tropical Storm – wind speed between 39 MPH and 73 MPH

H: Hurricane – wind speed between 74 MPH and 110 MPH

M: Major Hurricane – wind speed greater than 110 MPH

Bonnie is expected to make landfall north of Charleston on Sunday before weakening and moving north, Channel 2 Action News meteorologists said.

But in the metro Atlanta area, meteorologist Katie Walls said weather is expected to be dry and muggy, with a high of 86 degrees.

“We’ll continue with the abnormally warm conditions as we head in to the middle part of the work week,” Walls said.