HEC-HMS Technical Reference Manual Meteorology Precipitation Current: Precipitation Available Methods PDF Download PDF Download page Precipitation Available Methods. Current page All pages Precipitation Available Methods Available Precipitation methods are detailed on pages linked below:Historical storm methods:Gage WeightsGridded PrecipitationInterpolated PrecipitationInverse DistanceMetSim PrecipitationSpecified HyetographHypothetical (or design) storm methods:Frequency StormHMR 52 StormHypothetical StormStandard Project Storm ×