The influence of Two Distinct Mesoscale Circulations on Precipitation Patterns in the Coastal Carolinas

Two distinct mesoscale circulations are important to precipitation development and distribution in the coastal region of the Carolinas, U.S.A. during summer months.  These key mechanisms are the coastal sea-breeze front and the inland Sandhills circulation.  Differential heating of the land surface along the Sandhills consistently develops strong thunderstorms during summer.  The resultant convection in the Sandhills generates cool dense outflow forming a shallow density current, the Sandhills front.  The interaction of the Sandhills front and the sea-breeze front has been shown to trigger additional strong convection in the coastal region.

Conditions conducive for the occurrence of these interactions in the coastal Carolinas are examined.  A combination of remote sensing and in situ observations are used to identify the propagation of the Sandhills front and the sea-breeze front and their interactions.  Prevailing winds speeds are observed to impact the development of convection. Additionally, precipitation distributions resulting from these interactions are influenced by the background winds and moisture availability.  The highest total maximum and average precipitation amounts occur during southwesterly flow, bringing in ample moisture from the Gulf of Mexico.  The region between the coast and the Sandhills has the highest average precipitation amounts, where many interactions take place.