9726250 Colucci The goal of this project is to advance our understanding of the transition of the large-scale atmospheric flow in the Northern Hemisphere into a relatively stable flow pattern known as "blocking". The change to this flow pattern is one of the outstanding weather forecasting problems and the processes responsible for the transition are still not understood. Dr. Colucci will focus on two tasks. The first is to develop a climatology of pre-blocking flow conditions and identify, if possible, precursors to the transitions. This work will build upon preliminary work in which the initial results are promising, but will expand the climatology to include analyzed fields from the European Centre for Medium Range Forecasting (ECMWF) for additional years and at several levels. The second tasks involves the analysis of operational ensemble forecasts of blocking events and comparing those results with ensemble forecasts done with a research model at the National Center for Atmospheric Research. Insights gained from this research may well lead to improved medium range forecast capabilities.
