High-impact hydrometeorological events produce the most destructive and costly outcomes of any weather-driven phenomena worldwide. Furthermore, despite significant progress over the last several decades, forecasting and warning for these events still lacks the precision that could minimize loss of property and life, especially in developing nations. However, new observational platforms (in situ, remote) and data-collection methods are improving our ability to assess ongoing events as well as forecast and distinguish those that could be destructive from those that probably will not be. Excessive precipitation or runoff associated with tropical cyclones/convection, land-based convection, atmospheric rivers, ENSO, wintertime snowmelt, rain-on-snow, etc. results in both flash-flooding and large-river system floods whose characteristics often depend on local soils, vegetation/agriculture, and topography. Conversely, severe droughts create deleterious impacts on crop/food production and the water supply. In this session, papers are invited that contribute to our ability to improve real-time/operational forecasts and warnings for these kinds of extremes, especially observational and modeling approaches that may vary depending upon differing societal contexts. In addition, papers that address promising and innovative methods of assessing and modeling the statistics of observed hydrometeorological extremes as applied to real-time/operational forecasting/warning systems are encouraged. Papers that document forecast system performance vis-a-vis the effect of including new or additional observations are also encouraged, as well as new or innovative approaches to communicating vital "extremes" information to stakeholders.