Six-hourly analyses based on the special observational dataset from the Australian Monsoon Experiment are used to derive vorticity budget diagnostics for a number of tropical weather situations. The quality of the analyses is demonstrated by observation fitting statistics, comparison of digital satellite cloud imagery with diagnosed vertical motion, and by comparison of derived quantities with those obtained directly from the observations using line integral calculations. For the mean of the entire experimental period, balance generally exists between stretching and horizontal advection, with some contribution from an apparent vorticity source at upper levels. The individual-day behavior, however, is often quite different. Three categories are evident: 1) For weak, low-level cyclonic flows at the time of maximum convection (disorganized, deep convection), an apparent source of cyclonic vorticity is evident at low and high levels, and a sink is indicated through midlevels. These situations are characterized by a midlevel convergence maximum and a related cyclonic vorticity maximum. 2) For strong, low-level vorticity regimes (circulation systems with organized convection), an apparent sink of vorticity is evident everywhere below the convective outflow level, with a source above. These situations are characterized by deep convergence and a low level of maximum vorticity. 3) The third category, which seems to be associated with mostly stratiform regimes, is similar to 1), but a source is diagnosed at mid- to high levels (possibly associated with the stratiform cloud deck) with a sink farther aloft. The author postulates that die vertical structure of apparent vorticity sources is determined by the ascent and descent motions of the dominant cloud forms, which redistribute the background vorticity, and by enhanced boundary layer convergence as circulation systems spin up. The implications of the (a) midlevel convergence maximum and (b) apparent vorticity sources to the understanding and prediction of monsoon onset, midtropospheric cyclones, and tropical cyclone behavior are discussed. In a companion paper, a representation of the apparent heat and vorticity sources is implemented in a numerical model and used in simulations of the above weather phenomenon.