A mesoscale flow feature of convergent winds, 50 to 100 km in length, usually oriented north–south, just east of the Denver, Colorado area. The cause of the feature is an interaction of southerly low-level flow with an east–west ridge known as the Palmer Divide extending onto the eastern Colorado plains to the south of Denver. In addition to the convergent wind field, which has been shown to help initiate thunderstorms in the convective season, the flow within the convergent zone sometimes develops smaller-scale vortices, hence the name “convergence–vorticity zone. ”