What is the primary meteorological principle underlying the storm maximization procedure used in Probable Maximum Precipitation (PMP) estimation?

The primary meteorological principle underlying the storm maximization procedure used in Probable Maximum Precipitation (PMP) estimation is moisture maximization. The PMP represents the greatest depth of precipitation for a given duration meteorologically possible over a given storm area at a particular geographical location at a certain time of year. The storm maximization procedure takes an observed historical storm and hypothetically enhances its rainfall potential to its physical limits. Moisture maximization specifically involves adjusting the observed rainfall of a storm to reflect the maximum possible atmospheric moisture content that could have been present during that specific storm event, given its synoptic type and location. This adjustment assumes that all other meteorological factors influencing precipitation, such as storm dynamics, efficiency of rainfall production, storm movement, and vertical air mass uplift, remain at their most efficient observed levels for that storm, or are otherwise optimized. To achieve moisture maximization, the precipitable water (the total amount of water vapor in a vertical column of the atmosphere) in the storm's inflow air mass is maximized. This is typically accomplished by determining the highest recorded 12-hour duration persisting dew point temperature for the inflow area that is meteorologically reasonable for the storm's location and time of year. This maximum dew point temperature is then used to compute the maximum possible precipitable water through adiabatic lifting (the process of an air parcel cooling as it rises due to expansion, leading to condensation and precipitation if saturation is reached). A ratio is then calculated between this maximized precipitable water and the actual precipitable water observed during the original storm. This ratio serves as a multiplier applied to the observed storm rainfall to estimate the greatest possible precipitation that could have occurred if maximum moisture had been available.