  The concept of Maximum Potential Intensity (MPI) is widely used in tropical
cyclone research to estimate the minimum central pressure and the maximum
velocity of tropical storms from environmental parameters. The MPI pressure
derives from consideration of an idealized thermodynamic cycle, while the MPI
velocity additionally requires information about real-time power and heat flows
within the storm. Recently MPI velocity was proposed to be a substantial
overestimate (by 10-30 percent) presumably neglecting the power needed to lift
precipitating water (the gravitational power of precipitation). This conclusion
did not involve a theoretical analysis of the MPI concept but was based on
observed hurricane rainfall to estimate gravitational power of precipitation.
However, since the MPI pressure estimate does explicitly account for lifting
water, and the MPI velocity derives from this pressure, the question arises
whether a correction to MPI velocity is required. Here we represent and examine
the MPI derivations in their most general form and show that although a
correction to MPI velocity is justified, it is an order of magnitude or so
smaller than originally proposed. We show that the neglect of gravitational
power of precipitation in the MPI velocity estimate was caused by the
incomplete formulation of the general relationship between pressure work and
dissipation of kinetic energy, taken per unit time and integrated over the
storm. We highlight the importance of an internally consistent framework to
estimate both storm energy and power and provide some perspectives for further
investigating the role of moisture.
