Towards a Coordinated North American Daily Precipitation Analysis

Accurate and timely information on past precipitation is crucial for various environmental prediction applications, including hydrological forecasting, drought monitoring and forest fire prevention. Precipitation observations are also critical for the verification of numerical weather predictions, and are generally the most important forcing in land data assimilation systems. Hence, a reliable gridded precipitation dataset available in near real-time is of great value for many environmental prediction systems, some of which are shared between North American countries. For example, hydrological models provide guidance for managing watersheds shared between Canada and the U.S., as well as between the U.S. and Mexico. The three countries also jointly develop and use the North American Ensemble Forecasting System. In both cases, all parties involved need to come to an understanding as to which precipitation dataset to use. For this reason, as part of the North American Climate Services Partnership (NACSP) initiative, the US Climate Prediction Centre (CPC), the Canadian Meteorological Centre (CMC) and the Mexican National Water Commission (CONAGUA) are working towards the development of a coordinated daily precipitation analysis for North America, which should be completed by the end of 2016.

The first phase of this project consists in identifying national networks which could participate in a coordinated daily precipitation analysis, in addition to observations already shared over the Global Telecommunication System (GTS). From this database, a subset of stations has been identified which do not take part in the precipitation analysis, but are rather kept for verification purposes. During the second phase of the project, skill and bias of existing analysis systems are to be compared using this verification dataset, in order to identify their strengths and weaknesses. The challenge will then be to agree upon a methodology for obtaining a coordinated North American precipitation analysis, which will be made available to other users, and in particular to other NACSP projects.