A key weakness present in current hydrometeorological observing and forecasting methods is the capability to accurately characterize atmospheric moisture parameters in three and four dimensions. Additionally, observing atmospheric moisture characteristics over varying geographic regions adds to the challenge. Sounding retrievals from the HES sensor on the GOES-R system will allow for a greatly improved capability to characterize the three and four-dimensional atmospheric moisture fields. Improvements to the atmospheric moisture field observations and forecasts will lead, in turn, to more accurate precipitation forecasts and flooding potential assessments over the entire HES sensor coverage area. This paper will illustrate and discuss key moisture field observational improvements to be gained with the HES sensor in the GOES-R era.