How is Probable Maximum Precipitation (PMP) estimated?

PMP is theoretically maximum precipitation for a given area and duration with no assigned probability. Estimation methods: (1) Meteorological approach - moisture maximization (adjust observed storms to maximum dew point) and transposition (move storms to study location with adjustments), (2) Statistical extrapolation - extending frequency analysis to extreme events (Hershfield), (3) Generalized estimates from hydrometeorological reports (WMO, Bureau of Meteorology). PMP used for spillway design flood (PMF) for high-hazard dams. Climate change may require reassessment of historical PMP values.