A possible mechanism for the pressure wave is developed from the linear Bousinesq equations with heating and wind shear. In addition to the inhomogeneous continental tide, it shows eastward moving diurnal pulses of potential vorticity (PV) generated by imposed heating over the Rockies. Because of the background shear, they produce vertical motion in the lower troposphere.
The PV hypothesis is tested with the North American Regional Reanalysis (NARR) data. Diurnal drifting PV anomalies are found around 500 to 600 hPa level in both winter and summer. In winter the PV anomalies are weaker and seem to form further west, and they do not trigger convection, the eastward propagating signal only shows up in the surface pressure observation.