September has been a dry month across the entire Southeastern United States, including South Carolina.
Nearly 80% of the state is in a drought according to the most recent report from the National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln. Included in that statistic is a swath of the Midlands, from about Columbia and south that is considered to be in a “severe drought”. A dry pattern, caused in part by the tropical activity off the Atlantic coast and above average temperatures are the primary causes for the development of the abnormally dry conditions.
Dorian’s immediate impact on South Carolina is evident just by glancing at the drought monitor map. Most of the Low County and Pee Dee, which received Dorian’s outer rain bands are not considered in a drought. The areas further west and out of the reach of Dorian’s rains are considered in drought.
Dorian’s influence on the current drought reaches deeper than just its rain bands. Circulation around the tropical cyclone initiated a pattern of dry air wrapping into the region from the Northwest. In the wake of hurricanes Dorian and Humberto, atmospheric wave patterns have allowed hot and dry air to periodically build over the Southeast. This has both suppressed rainfall and enhanced evapotranspiration, thus expediting drought.
Many locations have received less than 10 percent of their normal rainfall for the month of September.
— Jeff Huffman (@HuffmanHeadsUp) September 30, 2019
Climatology suggests that there is roughly an even distribution of precipitation throughout the year in South Carolina, with a slight uptick in rainfall during July and August. Without an impending dry season (as is faced by Florid, which is also drought-stricken), it is possible that South Carolina can rebound from the dry conditions in the coming months as cold fronts and cool season weather systems become more frequent.