A Case Study of a Large-Amplitude Inertia–Gravity Wave over the Southeast
Surface observations, operational Doppler radar data, and satellite imagery all displayed the signatures of large-amplitude IGW activity in the Southeast on 7 March 2008. IGW passage was accompanied by maximum crest-to-trough surface pressure falls of 10 hPa (30 min)-1 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 southern Texas near the Rio Grande Valley in association with appreciable upper-level geostrophic imbalance. As the IGW amplified and propagated northeastward at an estimated 26 m s-1, the wave front developed a “sawtooth” pattern, possibly indicative of spatially variable ducting ability, and peaked in amplitude over parts of Mississippi, Alabama, and Tennessee. Though IGW genesis appeared to occur devoid of convection, amplification appeared to be favored along a sharp back edge to the precipitation shield and in the presence of a low-level stable layer that was situated above a surface-based layer of rain-cooled air.