Example of a quasi-stationary convective system. Note how well this case fits the conditions for a quasi-stationary convective system. Also note how the moisture convergence strengthens to the west of the original convection. The moisture convergence field is responding to changes in the surface pressure and wind fields as a weak upper level impulse approaches. The weak PV anomaly induced a weak surface low to move across Kansas. As it approached Iowa significant changes occurred to the field of moisture convergence. Forecasting MCS movement requires paying close attention to the hourly surface data and how the moisture convergence fields are changing. This heavy rainfall event knocked out the water works for Des Moines during the 1993 Midwest flood.