 Will the roads be icy tomorrow? Will therapy and afternoon thunderstorms? Bringing together computational forecasts and observations to create a set of forecasts can help us plan our day better and help scientists understand our system. In their explorers series lectures, Dr. Moha Garamte and Dr. Jeff Anderson tell us how ensemble prediction systems can tell us what we know and don't know about the future. I'm gonna start out with a very simple explanation that will say how systems like this that look very complex can be understood by ensemble data assimilation. And from there I'll show you a couple of examples of applications of data assimilation. We would like people to know that ensemble prediction system can be crucial, especially in extreme events. Ensemble data assimilation is one of the three key pieces of every weather forecast you see and really a crucial point for all of NCAR science.