A Case Study of a Large-Amplitude Inertia–Gravity Wave over the Southeast

Previous research has shown that the passage of large-amplitude inertia-gravity waves (IGWs) can have a significant impact on sensible weather. Examples of sensible weather effects associated with IGW passages include large variations in sea level pressure (SLP), significant wind shifts accompanied by damaging wind gusts, and the abrupt cessation of precipitation. The purpose of this analysis is to provide an overview of the environment that favors IGW genesis, organization, and maintenance, show the results of an analysis of a significant IGW event that occurred on 7 March 2008 and impacted the sensible weather over a good part of the inland Southeast, and compare and contrast this case with previously published cases.

Surface observations, operational Doppler radar data, and satellite imagery all displayed the signatures of moderate- and large-amplitude IGW activity in the Southeast on 7 March 2008. IGW passage was accompanied by SLP variations that exceeded 10 hPa in 40 min with vector wind shift of 20 m s-1, a sharp back edge to the precipitation shield in radar imagery, and cloud desiccation in satellite imagery. The observed IGW activity appeared to originate in southeastern Texas. As the IGW intensified and propagated northeastward at an estimated 30 m s-1, the wave front developed a “sawtooth” pattern, possibly indicative of multiple IGW activity, and was most intense over parts of Mississippi, Alabama, and Tennessee. Wave amplification appeared to be favored by the presence of a warm advection-enhanced low-level stable layer that was situated above a surface-based layer of rain-cooled air from previous convective and stratiform precipitation.