Science Issues Associated with Precipitation and Storm Extremes

Abstract:

The Third United States National Climate Assessment (NCA3) included several key messages about precipitation and storm extremes. Extreme rainfall has been increasing and is expected to continue to increase in the future. Droughts have been increasing in some regions and are projected to become more intense in most areas due to increases in evaporation. On certain aspects of precipitation and storms, strong statements were not made because of uncertainties in the science. Projections of flooding are uncertain because of the complexities of seasonal timing of extreme rainfall increases, counteracting influence of decreased soil moisture, and the interactions of climate changes with watershed characteristics. While droughts may increase in intensity in most areas, there are uncertainties in northern areas where precipitation may increase. Winter storm characteristics are likely to change but there are competing influences of increased temperatures, northward shift in tracks, and increases in atmospheric water content.