Mesoscale discussion

A mesoscale discussion (MD) is a short-term technical weather forecast (and nowcast) issued by the NOAA National Centers for Environmental Prediction (NCEP) national guidance centers. They typically are issued 1-6 hours prior to a weather event and contain a map illustrating relevant meteorological variables and the area covered. Forecasts concerning thunderstorms, such as high winds, hail, and tornadoes are mesoscale convective discussions (MCDs) issued by the Storm Prediction Center (SPC) and forecasts concerning precipitation (heavy rainfall, flash flooding) are mesoscale precipitation discussions (MPDs) issued by the Weather Prediction Center (WPC).