Sudden Nocturnal Warming Events in Mississippi

Abstract

Significant episodes of sudden nocturnal warming have been observed by the Mississippi Mesonet. The probable relation of these nocturnal warming events to surface layer regime transitions between a decoupled quiescent surface layer and a more turbulent, less thermodynamically stable surface layer is discussed within the context of four examples with different temporal signatures. In general, the changes in wind speed and inversion strength are consistent with expectations for such regime changes. However, details of individual events indicate a wider variety of event characteristics than has been documented previously. The cases examined are proposed as prototypes for four different types of warming event, based on the evolution of temperature and dewpoint as well as on whether clear forcing from a mesoscale or synoptic frontal passage can be identified. Using this classification system and a subjective evaluation of event magnitude, the frequency of nocturnal warming events is analyzed for four mesonet stations at varying distance inland over the period of record.