Amplitudes of 1-15 hPa/MB and Wavelengths of 50-500 KM (Uccellini and Koch, 1987) Periods of 1-4 HR

Most likely energy source mechanisms are latent heat release in deep convection and shear instability in which waves can extract energy from the Jet Stream when vertical wind shear is sufficiently strong to reduce the Richardson number below 0.25. Alternatively wave energy loss can be prevented by an efficient wave duct, which appears to be the most prevalent of the three mechanisms described. 

Strongest upward motions with Gravity Waves occur just following the surface pressure trough and lead to maximum precipitation rates just ahead of the ridge.

Gravity waves typically form within or near the back edge of a precipitation shield.

Recent studies indicate that Gravity Waves may occur as frequently as 34% of the time in the Central US during the Winter months.

Current poor understanding of gravity waves and acknowledged skepticism of their existence stems from the fact that it is both difficult and tedious to conduct a study of even a single event. In addition forecasters have often been mislead by the existence of large scale gravity waves in 2 noteworthy events.

• Rapid pressure falls associated with a strong gravity wave mislead forecasters into believing that secondary cyclogenesis was taking place along a coastal front (Bosart and Seimon, 1988).
• Schneider (1990) presented a case which occurred in Illinois in December 1987 in which the minimum pressure associated with one of the wave troughs was lower than that of the synoptic scale cyclone through which it passed. The isallobaric fall region associated with the wave was noted by forecasters, who lacking knowledge of the wave, mistakenly attempted to correct the model forecasts of the track.

• 5 MIN sampling by ASOS - The availability of high temporal resolution data from ASOS is an important factor  in the determination of whether an operational detection of gravity waves is feasible.
• ASOS data is expected to meet that need. ASOS allows for the automated bandpass filtering of digital pressure time series data.
• 6 MIN Wind Profiles
• WSR-88D VWP/VAD winds