Swaths of heavy rain are expected to spread across the Palmetto State over the weekend. The rain will be heavy enough to cause river and street flooding, but there are still questions as to which parts of the state will see the greatest amounts.
An area of low pressure is forecast to form in the central Gulf of Mexico and gradually strengthen as it moves northeastward over the Southeastern United States. The first area to receive widespread heavy rain is likely to be the Lowcountry Saturday night into Sunday morning, spreading over the remainder of the state Sunday afternoon through Sunday night. The trough of low pressure in the upper part of the atmosphere will prolong the rain over a large portion of the state on Monday before finally pulling away on Tuesday.
The greatest threat from the storm system is excessive rain. Computer model projections as of Friday afternoon are showing widespread 2 to 4 inch rainfall amounts over the state. Some portions of the state could receive in excess of 6 inches of rain. There are some indications from the American and European global models that the Lowcountry, Pee Dee, or Midlands are the most likely areas to receive the most rain, but forecasting the precise location of flooding downpours more than a few hours in advance is typically not possible.
The National Weather Service says flooding of low-lying and poorly drained areas are possible. Strong northeast winds combined with the heavy rain so coastal flooding is likely, especially along in vulnerable areas of Charleston county. The prolonged nature of the rain raises the concern of river and small stream flooding.
A clearing trend is expected to finally take place in time for Christmas, along with above average temperatures.